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Ito R, Kamiya M, Takayama K, Mori S, Matsumoto R, Takebayashi M, Ojima H, Fujimura S, Yamamoto H, Ohno M, Ihara M, Okajima T, Yamashita A, Colman F, Lycett GJ, Sattelle DB, Matsuda K. Unravelling nicotinic receptor and ligand features underlying neonicotinoid knockdown actions on the malaria vector mosquito Anopheles gambiae. Open Biol 2024; 14:240057. [PMID: 39043224 PMCID: PMC11265914 DOI: 10.1098/rsob.240057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Accepted: 05/21/2024] [Indexed: 07/25/2024] Open
Abstract
With the spread of resistance to long-established insecticides targeting Anopheles malaria vectors, understanding the actions of compounds newly identified for vector control is essential. With new commercial vector-control products containing neonicotinoids under development, we investigate the actions of 6 neonicotinoids (imidacloprid, thiacloprid, clothianidin, dinotefuran, nitenpyram and acetamiprid) on 13 Anopheles gambiae nicotinic acetylcholine receptor (nAChR) subtypes produced by expression of combinations of the Agα1, Agα2, Agα3, Agα8 and Agβ1 subunits in Xenopus laevis oocytes, the Drosophila melanogaster orthologues of which we have previously shown to be important in neonicotinoid actions. The presence of the Agα2 subunit reduces neonicotinoid affinity for the mosquito nAChRs, whereas the Agα3 subunit increases it. Crystal structures of the acetylcholine binding protein (AChBP), an established surrogate for the ligand-binding domain, with dinotefuran bound, shows a unique target site interaction through hydrogen bond formation and CH-N interaction at the tetrahydrofuran ring. This is of interest as dinotefuran is also under trial as the toxic element in baited traps. Multiple regression analyses show a correlation between the efficacy of neonicotinoids for the Agα1/Agα2/Agα8/Agβ1 nAChR, their hydrophobicity and their rate of knockdown of adult female An. gambiae, providing new insights into neonicotinoid features important for malaria vector control.
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Affiliation(s)
- Ryo Ito
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan
| | - Masaki Kamiya
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan
| | - Koichi Takayama
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan
| | - Sumito Mori
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan
| | - Rei Matsumoto
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan
| | - Mayuka Takebayashi
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan
| | - Hisanori Ojima
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan
| | - Shota Fujimura
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan
| | - Haruki Yamamoto
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan
| | - Masayuki Ohno
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan
| | - Makoto Ihara
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan
| | - Toshihide Okajima
- Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Atsuko Yamashita
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Fraser Colman
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Gareth J. Lycett
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - David B. Sattelle
- Centre for Respiratory Biology, UCL Respiratory, Division of Medicine, University College London, London WC1E 6JF, UK
| | - Kazuhiko Matsuda
- Department of Applied Biological Chemistry, Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan
- Agricultural Technology and Innovation Research Institute, Kindai University, 3327-204 Nakamachi, Nara 631-8505, Japan
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Lynd A, Gonahasa S, Staedke SG, Oruni A, Maiteki-Sebuguzi C, Hancock PA, Knight E, Dorsey G, Opigo J, Yeka A, Katureebe A, Kyohere M, Hemingway J, Kamya MR, McDermott D, Lucas ER, Donnelly MJ. LLIN Evaluation in Uganda Project (LLINEUP)-effects of a vector control trial on Plasmodium infection prevalence and genotypic markers of insecticide resistance in Anopheles vectors from 48 districts of Uganda. Sci Rep 2024; 14:14488. [PMID: 38914669 PMCID: PMC11196729 DOI: 10.1038/s41598-024-65050-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 06/17/2024] [Indexed: 06/26/2024] Open
Abstract
Pyrethroid bednets treated with the synergist piperonyl butoxide (PBO) offer the possibility of improved vector control in mosquito populations with metabolic resistance. In 2017-2019, we conducted a large-scale, cluster-randomised trial (LLINEUP) to evaluate long-lasting insecticidal nets (LLINs) treated with a pyrethroid insecticide plus PBO (PBO LLINs), as compared to conventional, pyrethroid-only LLINs across 104 health sub-districts (HSDs) in Uganda. In LLINEUP, and similar trials in Tanzania, PBO LLINs were found to provide greater protection against malaria than conventional LLINs, reducing parasitaemia and vector density. In the LLINEUP trial, we conducted cross-sectional household entomological surveys at baseline and then every 6 months for two years, which we use here to investigate longitudinal changes in mosquito infection rate and genetic markers of resistance. Overall, 5395 female Anopheles mosquitoes were collected from 5046 households. The proportion of mosquitoes infected (PCR-positive) with Plasmodium falciparum did not change significantly over time, while infection with non-falciparum malaria decreased in An. gambiae s.s., but not An. funestus. The frequency of genetic markers associated with pyrethroid resistance increased significantly over time, but the rate of change was not different between the two LLIN types. The knock-down resistance (kdr) mutation Vgsc-995S declined over time as Vgsc-995F, the alternative resistance mutation at this codon, increased. Vgsc-995F appears to be spreading into Uganda. Distribution of LLINs in Uganda was previously found to be associated with reductions in parasite prevalence and vector density, but here we show that the proportion of infective mosquitoes remained stable across both PBO and non-PBO LLINs, suggesting that the potential for transmission persisted. The increased frequency of markers of pyrethroid resistance indicates that LLIN distribution favoured the evolution of resistance within local vectors and highlights the potential benefits of resistance management strategies.Trial registration: This study is registered with ISRCTN, ISRCTN17516395. Registered 14 February 2017, http://www.isrctn.com/ISRCTN17516395 .
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Affiliation(s)
- Amy Lynd
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Samuel Gonahasa
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Sarah G Staedke
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Ambrose Oruni
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | | | | | - Erin Knight
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Grant Dorsey
- University of California, San Francisco, San Francisco, CA, 94110, USA
| | | | - Adoke Yeka
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Agaba Katureebe
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Mary Kyohere
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Janet Hemingway
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
- Department of Medicine, Makerere University, Kampala, Uganda
| | - Daniel McDermott
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Eric R Lucas
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Martin J Donnelly
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
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Djègbè I, Hessou-Djossou D, Gounou Boukari MKY, Nonfodji O, Tchigossou G, Djouaka R, Cornelie S, Akogbeto M, Djogbenou L, Chandre F. Physico-chemical characterization of Anopheles gambiae s.l. breeding sites and kdr mutations in urban areas of Cotonou and Natitingou, Benin. BMC Infect Dis 2024; 24:545. [PMID: 38816702 PMCID: PMC11140934 DOI: 10.1186/s12879-024-09440-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 05/27/2024] [Indexed: 06/01/2024] Open
Abstract
BACKGROUND This study aimed to investigate the relationship between the physicochemical characteristics of An. gambiae s.s. and An. coluzzii breeding sites, the susceptibility profiles to commonly used insecticides in public health, and the underlying insecticide resistance mechanisms. METHODS Anopheles breeding sites surveys were conducted in Cotonou and Natitingou in September 2020, January and August 2021. Physicochemical properties and bacterial loads were determined in individual breeding sites. The WHO susceptibility assays were carried out using the female of the emerging adult mosquitoes. Anopheles species were identified through PCR techniques. Kdr L1014F/S, N1575Y and G119S mutations were investigated using TaqMan genotyping assays. RESULTS Molecular analysis showed that all mosquitoes analyzed in Cotonou were Anopheles coluzzii, while those of Natitingou were Anopheles gambiae s.s. Fecal coliforms were identified as playing a role in this distribution through their significant influence on the presence of An. coluzzii larvae. WHO susceptibility assay indicated a high level of resistance to deltamethrin in the two cities. The resistance levels to deltamethrin were higher in Cotonou (X2 = 31.689; DF = 1; P < 0.0001). There was a suspected resistance to bendiocarb in Cotonou, whereas the mosquito population in Natitingou was resistant. The kdr L1014F mutation was highly observed in both mosquito populations (frequence: 86-91%), while the Ace-1 mutation was found in a small proportion of mosquitoes. In Cotonou, salinity was the only recorded physicochemical parameter that significantly correlated with the resistance of Anopheles mosquitoes to deltamethrin (P < 0.05). In Natitingou, significant correlations were observed between the allelic frequencies of the kdr L1014F mutation and pH, conductivity, and TDS. CONCLUSION These results indicate a high level of pyrethroid resistance in the anopheles populations of both Cotonou and Natitingou. Moreover, this study report the involvement of abiotic factors influencing Anopheles susceptibility profile.
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Affiliation(s)
- Innocent Djègbè
- Département des Sciences de la Vie et de la Terre, Ecole Normale Supérieure de Natitingou, Natitingou, Bénin
- Plateforme Agriculture Environnement Santé, Institut International d'Agriculture Tropicale (IITA-Bénin), Cotonou, Bénin
| | - Donald Hessou-Djossou
- Département des Sciences de la Vie et de la Terre, Ecole Normale Supérieure de Natitingou, Natitingou, Bénin.
| | | | - Odilon Nonfodji
- Laboratoire de Chimie de l'Eau et de l'Environnement (LCEE), Ecole Normale Supérieure de Natitingou, UNSTIM, Natitingou, Bénin
| | - Geneviève Tchigossou
- Plateforme Agriculture Environnement Santé, Institut International d'Agriculture Tropicale (IITA-Bénin), Cotonou, Bénin
| | - Rousseau Djouaka
- Plateforme Agriculture Environnement Santé, Institut International d'Agriculture Tropicale (IITA-Bénin), Cotonou, Bénin
| | - Sylvie Cornelie
- Evolution et Contrôle, UMR IRD 224-CNRS, Université de Montpellier2. MIVEGEC. Maladies Infectieuses et Vecteurs : Ecologie, Génétique, Montpellier cedex 5, 5290, France
| | - Martin Akogbeto
- Centre de Recherche Entomologique de Cotonou (CREC), Ministère de la Santé, Cotonou, Bénin
| | - Luc Djogbenou
- Institut Régional de Santé Publique (IRSP), Université d'Abomey-Calavi (UAC), Ouidah, Bénin
| | - Fabrice Chandre
- Evolution et Contrôle, UMR IRD 224-CNRS, Université de Montpellier2. MIVEGEC. Maladies Infectieuses et Vecteurs : Ecologie, Génétique, Montpellier cedex 5, 5290, France
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Ekra AK, Edi CAV, Gbalegba GCN, Zahouli JZB, Danho M, Koudou BG. Can neonicotinoid and pyrrole insecticides manage malaria vector resistance in high pyrethroid resistance areas in Côte d'Ivoire? Malar J 2024; 23:160. [PMID: 38778399 PMCID: PMC11112771 DOI: 10.1186/s12936-024-04917-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Accepted: 03/23/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND Anopheles mosquito resistance to insecticide remains a serious threat to malaria vector control affecting several sub-Sahara African countries, including Côte d'Ivoire, where high pyrethroid, carbamate and organophosphate resistance have been reported. Since 2017, new insecticides, namely neonicotinoids (e.g.; clothianidin) and pyrroles (e.g.; chlorfenapyr) have been pre-qualified by the World Health Organization (WHO) for use in public health to manage insecticide resistance for disease vector control. METHODS Clothianidin and chlorfenapyr were tested against the field-collected Anopheles gambiae populations from Gagnoa, Daloa and Abengourou using the WHO standard insecticide susceptibility biossays. Anopheles gambiae larvae were collected from several larval habitats, pooled and reared to adulthood in each site in July 2020. Non-blood-fed adult female mosquitoes aged 2 to 5 days were exposed to diagnostic concentration deltamethrin, permethrin, alpha-cypermethrin, bendiocarb, and pirimiphos-methyl. Clothianidin 2% treated papers were locally made and tested using WHO tube bioassay while chlorfenapyr (100 µg/bottle) was evaluated using WHO bottle assays. Furthermore, subsamples of exposed mosquitoes were identified to species and genotyped for insecticide resistance markers including the knock-down resistance (kdr) west and east, and acetylcholinesterase (Ace-1) using molecular techniques. RESULTS High pyrethroid resistance was recorded with diagnostic dose in Abengourou (1.1 to 3.4% mortality), in Daloa (15.5 to 33.8%) and in Gagnoa (10.3 to 41.6%). With bendiocarb, mortality rates ranged from 49.5 to 62.3%. Complete mortality (100% mortality) was recorded with clothianidin in Gagnoa, 94.9% in Daloa and 96.6% in Abengourou, while susceptibility (mortality > 98%) to chlorfenapyr 100 µg/bottle was recorded at all sites and to pirimiphos-methyl in Gagnoa and Abengourou. Kdr-west mutation was present at high frequency (0.58 to 0.73) in the three sites and Kdr-east mutation frequency was recorded at a very low frequency of 0.02 in both Abengourou and Daloa samples and absent in Gagnoa. The Ace-1 mutation was present at frequencies between 0.19 and 0.29 in these areas. Anopheles coluzzii represented 100% of mosquitoes collected in Daloa and Gagnoa, and 72% in Abengourou. CONCLUSIONS This study showed that clothianidin and chlorfenapyr insecticides induce high mortality in the natural and pyrethroid-resistant An. gambiae populations in Côte d'Ivoire. These results could support a resistance management plan by proposing an insecticide rotation strategy for vector control interventions.
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Affiliation(s)
- Armand K Ekra
- UMRI 28, Sciences Agronomiques et Procédés de Transformation, Laboratoire de Zoologie Agricole et Entomologie, Institut National Polytechnique Félix Houphouët-Boigny (INP-HB), Yamoussoukro, République de Côte d'Ivoire.
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, République de Côte d'Ivoire.
| | - Constant A V Edi
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, République de Côte d'Ivoire
| | | | - Julien Z B Zahouli
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, République de Côte d'Ivoire
- Centre d'Entomologie Médicale et Vétérinaire, Université Alassane Ouattara, Bouaké, République de Côte d'Ivoire
| | - Mathias Danho
- UMRI 28, Sciences Agronomiques et Procédés de Transformation, Laboratoire de Zoologie Agricole et Entomologie, Institut National Polytechnique Félix Houphouët-Boigny (INP-HB), Yamoussoukro, République de Côte d'Ivoire
| | - Benjamin G Koudou
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, République de Côte d'Ivoire
- Laboratoire d'Entomologie, UFR Sciences de la Nature, Université Nangui Abrogoua, Abidjan, République de Côte d'Ivoire
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Fadel AN, Ibrahim SS, Sandeu MM, Tatsinkou CGM, Menze BD, Irving H, Hearn J, Nagi SC, Weedall GD, Terence E, Tchapga W, Wanji S, Wondji CS. Exploring the molecular mechanisms of increased intensity of pyrethroid resistance in Central African population of a major malaria vector Anopheles coluzzii. Evol Appl 2024; 17:e13641. [PMID: 38410533 PMCID: PMC10895554 DOI: 10.1111/eva.13641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 12/14/2023] [Accepted: 01/01/2024] [Indexed: 02/28/2024] Open
Abstract
Molecular mechanisms driving the escalation of pyrethroid resistance in the major malaria mosquitoes of Central Africa remain largely uncharacterized, hindering effective management strategies. Here, resistance intensity and the molecular mechanisms driving it were investigated in a population of Anopheles coluzzii from northern Cameroon. High levels of pyrethroid and organochloride resistance were observed in An. coluzzii population, with no mortality for 1× permethrin; only 11% and 33% mortalities for 5× and 10× permethrin diagnostic concentrations, and <2% mortalities for deltamethrin and DDT, respectively. Moderate bendiocarb resistance (88% mortality) and full susceptibility to malathion were observed. Synergist bioassays with piperonyl butoxide recovered permethrin susceptibility, with mortalities increasing to 53.39%, and 87.30% for 5× and 10× permethrin, respectively, implicating P450 monooxygenases. Synergist bioassays with diethyl maleate (DEM) recovered permethrin and DDT susceptibilities (mortalities increasing to 34.75% and 14.88%, respectively), implicating glutathione S-transferases. RNA-seq-based genome-wide transcriptional analyses supported by quantitative PCR identified glutathione S-transferase, GSTe2 (RNA-seqFC = 2.93 and qRT-PCRFC = 8.4, p < 0.0043) and CYP450, CYP6Z2 (RNA-seqFC = 2.39 and qRT-PCRFC = 11.7, p < 0.0177) as the most overexpressed detoxification genes in the pyrethroid-resistant mosquitoes, compared to mosquitoes of the susceptible Ngousso colony. Other overexpressed genes include P450s, CYP6M2 (FC = 1.68, p < 0.0114), CYP4G16 (FC = 2.02, p < 0.0005), and CYP4G17 (FC = 1.86, p < 0.0276). While high frequency of the 1014F kdr mutation (50%) and low frequencies of 1014S (6.61%) and 1575Y (10.29%) were observed, no ace-1 mutation was detected in bendiocarb-resistant populations, suggesting the preeminent role of metabolic mechanism. Overexpression of metabolic resistance genes (including GSTe2 and CYP6Z2 known to confer resistance to multiple insecticides) in An. coluzzii from the Sudan Savannah of Cameroon highlights the need for alternative management strategies to reduce malaria burden in northern Cameroon.
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Affiliation(s)
- Amen N. Fadel
- Center for Research in Infectious Diseases (CRID)YaoundéCameroon
- Department of Microbiology and ParasitologyUniversity of BueaBueaCameroon
| | - Sulaiman S. Ibrahim
- Center for Research in Infectious Diseases (CRID)YaoundéCameroon
- Department of BiochemistryBayero UniversityKanoNigeria
- Vector Biology DepartmentLiverpool School of Tropical Medicine (LSTM)LiverpoolUK
| | - Maurice M. Sandeu
- Center for Research in Infectious Diseases (CRID)YaoundéCameroon
- Department of Microbiology and Infectious DiseasesSchool of Veterinary Medicine and SciencesUniversity of NgaoundéréNgaoundéréCameroon
| | | | | | - Helen Irving
- Vector Biology DepartmentLiverpool School of Tropical Medicine (LSTM)LiverpoolUK
| | - Jack Hearn
- Centre of Epidemiology and Planetary HealthNorth FacultyVeterinary & Animal ScienceScotland's Rural CollegeInvernessUK
| | - Sanjay C. Nagi
- Vector Biology DepartmentLiverpool School of Tropical Medicine (LSTM)LiverpoolUK
| | - Gareth D. Weedall
- School of Biological and Environmental SciencesLiverpool John Moores UniversityLiverpoolUK
| | - Ebai Terence
- Center for Research in Infectious Diseases (CRID)YaoundéCameroon
| | - Williams Tchapga
- Center for Research in Infectious Diseases (CRID)YaoundéCameroon
| | - Samuel Wanji
- Department of Microbiology and ParasitologyUniversity of BueaBueaCameroon
| | - Charles S. Wondji
- Center for Research in Infectious Diseases (CRID)YaoundéCameroon
- Vector Biology DepartmentLiverpool School of Tropical Medicine (LSTM)LiverpoolUK
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Akuoko OK, Dhikrullahi SB, Hinne IA, Mohammed AR, Owusu-Asenso CM, Coleman S, Dadzie SK, Kyerematen R, Boakye DA, Wilson MD, Afrane YA. Biting behaviour, spatio-temporal dynamics, and the insecticide resistance status of malaria vectors in different ecological zones in Ghana. Parasit Vectors 2024; 17:16. [PMID: 38195546 PMCID: PMC10775458 DOI: 10.1186/s13071-023-06065-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Accepted: 11/20/2023] [Indexed: 01/11/2024] Open
Abstract
BACKGROUND A significant decrease in malaria morbidity and mortality has been attained using long-lasting insecticide-treated nets and indoor residual spraying. Selective pressure from these control methods influences changes in vector bionomics and behavioural pattern. There is a need to understand how insecticide resistance drives behavioural changes within vector species. This study aimed to determine the spatio-temporal dynamics and biting behaviour of malaria vectors in different ecological zones in Ghana in an era of high insecticide use for public health vector control. METHODS Adult mosquitoes were collected during the dry and rainy seasons in 2017 and 2018 from five study sites in Ghana in different ecological zones. Indoor- and outdoor-biting mosquitoes were collected per hour from 18:00 to 06:00 h employing the human landing catch (HLC) technique. Morphological and molecular species identifications of vectors were done using identification keys and PCR respectively. Genotyping of insecticide-resistant markers was done using the TaqMan SNP genotyping probe-based assays. Detection of Plasmodium falciparum sporozoites was determined using PCR. RESULTS A total of 50,322 mosquitoes belonging to four different genera were collected from all the study sites during the sampling seasons in 2017 and 2018. Among the Anophelines were Anopheles gambiae s.l. 93.2%, (31,055/33,334), An. funestus 2.1%, (690/33,334), An. pharoensis 4.6%, (1545/33,334), and An. rufipes 0.1% (44/33,334). Overall, 76.4%, (25,468/33,334) of Anopheles mosquitoes were collected in the rainy season and 23.6%, (7866/33,334) in the dry season. There was a significant difference (Z = 2.410; P = 0.0160) between indoor-biting (51.1%; 15,866/31,055) and outdoor-biting An. gambiae s.l. (48.9%; 15,189/31,055). The frequency of the Vgsc-1014F mutation was slightly higher in indoor-biting mosquitoes (54.9%) than outdoors (45.1%). Overall, 44 pools of samples were positive for P. falciparum CSP giving an overall sporozoite rate of 0.1%. CONCLUSION Anopheles gambiae s.l. were more abundant indoors across all ecological zones of Ghana. The frequency of G119S was higher indoors than outdoors from all the study sites, but with higher sporozoite rates in outdoor mosquitoes in Dodowa and Kpalsogu. There is, therefore, an urgent need for a supplementary malaria control intervention to control outdoor-biting mosquitoes.
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Affiliation(s)
- Osei K Akuoko
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana
- African Regional Post-Graduate Programme in Insect Science, College of Basic and Applied Science, University of Ghana, Legon, Accra, Ghana
| | - Shittu B Dhikrullahi
- Department of Medical Microbiology, Centre for Vector-Borne Diseases Research, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Isaac A Hinne
- Department of Medical Microbiology, Centre for Vector-Borne Diseases Research, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
- Department of Biochemistry and Molecular Biology, CABNR, University of Nevada, Reno, NV, USA
| | - Abdul R Mohammed
- African Regional Post-Graduate Programme in Insect Science, College of Basic and Applied Science, University of Ghana, Legon, Accra, Ghana
- Department of Medical Microbiology, Centre for Vector-Borne Diseases Research, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Christopher M Owusu-Asenso
- Department of Medical Microbiology, Centre for Vector-Borne Diseases Research, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Sylvester Coleman
- Department of Clinical Microbiology - Vector Biology Laboratory, School of Medicine and Dentistry (SMD)-College of Health Sciences, Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana
| | - Samuel K Dadzie
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana
| | - Rosina Kyerematen
- African Regional Post-Graduate Programme in Insect Science, College of Basic and Applied Science, University of Ghana, Legon, Accra, Ghana
- Department of Animal Biology and Conservation Science, College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
| | - Daniel A Boakye
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana
| | - Michael D Wilson
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana
| | - Yaw A Afrane
- Department of Medical Microbiology, Centre for Vector-Borne Diseases Research, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana.
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Boussougou-Sambe ST, Ngossanga B, Doumba-Ndalembouly AG, Boussougou LN, Woldearegai TG, Mougeni F, Mba TN, Edoa JR, Dejon-Agobé JC, Awono-Ambene P, Kremsner PG, Kenguele HM, Borrmann S, Mordmüller B, Adegnika AA. Anopheles gambiae s.s. resistance to pyrethroids and DDT in semi-urban and rural areas of the Moyen-Ogooué Province, Gabon. Malar J 2023; 22:382. [PMID: 38110952 PMCID: PMC10729327 DOI: 10.1186/s12936-023-04820-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 12/12/2023] [Indexed: 12/20/2023] Open
Abstract
BACKGROUND Pyrethroids are the main insecticides used in vector control for malaria. However, their extensive use in the impregnation of long-lasting insecticidal nets (LLINs) and indoor residual spraying has led to the development of resistance, threatening its success as a tool for malaria control. Baseline data prior to large scale distribution of LLINs are important for the implementation of efficient strategies. However, no data on the susceptibility of malaria vectors is available in the Moyen-Ogooué Province in Gabon. The aim of this study was to assess the susceptibility to pyrethroids and organochlorides of malaria vectors from a semi-urban and rural areas of the province and to determine the frequency of insecticide resistance genes. METHODS Larvae were collected from breeding sites in Lambaréné and Zilé and reared to adults. Three to five-day old female Anopheles gambiae sensu lato mosquitoes were used in cone tube assays following the WHO susceptibility tests protocol for adult mosquitoes. A subsample was molecularly identified using the SINE200 protocol and the frequency of Vgsc-1014 F and - 1014 S mutations were determined. RESULTS Anopheles gambiae sensu stricto (s.s.) was the sole species present in both Lambaréné and Zilé. Mosquito populations from the two areas were resistant to pyrethroids and organochlorides. Resistance was more pronounced for permethrin and DDT with mortality lower than 7% for both insecticides in the two study areas. Mosquitoes were statistically more resistant (P < 0.0001) to deltamethrin in Lambaréné (51%) compared to Zilé (76%). All the mosquitoes tested were heterozygous or homozygous for the knockdown resistance (Kdr) mutations Vgsc-L1014F and Vgsc-L1014S with a higher proportion of Vgsc-L1014F homozygous in Lambaréné (76.7%) compared to Zilé (57.1%). CONCLUSION This study provides evidence of widespread resistance to pyrethroids in An. gambiae s.s., the main malaria vector in the Moyen-Ogooué Province. Further investigation of the mechanisms underlining the resistance of An. gambiae s.s. to pyrethroids is needed to implement appropriate insecticide resistance management strategies.
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Affiliation(s)
| | | | | | | | - Tamirat Gebru Woldearegai
- Institut für Tropenmedizin, Eberhard-Karls-Universität, Tübingen, Germany
- German Center for Infection Research (DZIF), Partner Site, Tübingen, Germany
| | - Fabrice Mougeni
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
| | | | | | | | - Parfait Awono-Ambene
- Institut de Recherche de Yaoundé, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), B.P. 288, Yaoundé, Cameroon
| | - Peter G Kremsner
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- Institut für Tropenmedizin, Eberhard-Karls-Universität, Tübingen, Germany
- German Center for Infection Research (DZIF), Partner Site, Tübingen, Germany
| | | | - Steffen Borrmann
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- Institut für Tropenmedizin, Eberhard-Karls-Universität, Tübingen, Germany
| | - Benjamin Mordmüller
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- Institut für Tropenmedizin, Eberhard-Karls-Universität, Tübingen, Germany
- Department of Medical Microbiology, Radboudumc, Nijmegen, The Netherlands
| | - Ayôla Akim Adegnika
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- Institut für Tropenmedizin, Eberhard-Karls-Universität, Tübingen, Germany
- German Center for Infection Research (DZIF), Partner Site, Tübingen, Germany
- Fondation pour la Recherche Scientifique (FORS), Cotonou, Benin
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Hong H, Eom TH, Trinh TTT, Tuan BD, Park H, Yeo SJ. Identification of breeding habitats and kdr mutations in Anopheles spp. in South Korea. Malar J 2023; 22:381. [PMID: 38104158 PMCID: PMC10724954 DOI: 10.1186/s12936-023-04821-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 12/12/2023] [Indexed: 12/19/2023] Open
Abstract
BACKGROUND Malaria is still endemic in South Korea. However, limited information is available on the current Anopheles breeding sites and the occurrence of insecticide resistance-associated genetic mutations and their distribution needed to control the malaria vector efficiently. METHODS This study explored breeding sites of Anopheline adults in Gimpo-si, near the demilitarized zone (DMZ) in Gyeonggi-do province, South Korea, from 2022 to 2023. Genetic diversity was investigated based on the internal transcribed spacer (ITS2), cytochrome c oxidase subunit I (COI), and knockdown resistance (kdr) genes of Anopheles mosquitoes. A natural environment associated with the seasonal abundance of Anopheles larvae was characterized. RESULTS Two breeding sites of Anopheles larvae and adults were found at a stream margin or shallow freshwater near the forest in Wolgot-myeon in Gimpo-si without cattle shed within 1 km and in Naega-myeon in Ganghwa-gun with cow shed within 100 m in 2022 and 2023, respectively. Both sites were located between the newly cultivated lands and the forest. Besides, both breeding sites were in the valley at a slight elevation of 60-70 m from ground lands and maintained the shadow all day. Overall, the Wolgot-myeon breeding site showed various Anopheles spp. larvae, including Anopheles sinensis. Naega-myeon, an additional breeding site found in 2023, had Anopheles sineroides larvae, and approximately 59.7% (89/149) of An. sinensis adults inhabited within a 100-m distance. The total collection, including larvae and adults, revealed that An. sinensis, Anopheles pullus, Anopheles kleini, An. sineroides, Anopheles belenrae, and Anopheles lindesayi accounted for 44.2% (118/267), 0.7% (2/267), 0.7% (2/267), 22.1% (59/267), 1.9% (5/267), and 30.3% (81/267), respectively. Furthermore, various kdr mutant genotypes (F/F, C/C, L/F, L/C and F/C) in An. sinensis, and the first kdr allele mutant (L/F1014) in An. belenrae were identified in South Korea. CONCLUSIONS Two breeding sites of Anopheles larvae were studied in Wolgot-myeon and Naega-myeon. Various Anopheles spp. larvae were detected in both habitats, but overall, An. sinensis was the most prevalent adults in both study sites. The occurrence of kdr allele mutant of An. belenrae in South Korea was reported. Rigorous larvae monitoring of Anopheles spp., continuously updating information on Anopheles breeding sites, and understanding the environmental conditions of Anopheles habitats are required to develop an effective malaria control programme in South Korea.
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Affiliation(s)
- Hyelee Hong
- Department of Tropical Medicine and Parasitology, Department of Biomedical Sciences, College of Medicine, Seoul National University, Seoul, 03080, Republic of Korea
| | - Tae-Hui Eom
- Department of Tropical Medicine and Parasitology, Department of Biomedical Sciences, College of Medicine, Seoul National University, Seoul, 03080, Republic of Korea
| | - Thuy-Tien Thi Trinh
- Department of Tropical Medicine and Parasitology, Medical Research Center, Institute of Endemic Diseases, Seoul National University, Seoul, 03080, Republic of Korea
| | - Bao Duong Tuan
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, 460 Iksan-Daero, Iksan, 54538, Republic of Korea
| | - Hyun Park
- Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, 460 Iksan-Daero, Iksan, 54538, Republic of Korea
| | - Seon-Ju Yeo
- Department of Tropical Medicine and Parasitology, Department of Biomedical Sciences, College of Medicine, Seoul National University, Seoul, 03080, Republic of Korea.
- Department of Tropical Medicine and Parasitology, Medical Research Center, Institute of Endemic Diseases, Seoul National University, Seoul, 03080, Republic of Korea.
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Zoh MG, Bonneville JM, Laporte F, Tutagata J, Sadia CG, Fodjo BK, Mouhamadou CS, McBeath J, Schmitt F, Horstmann S, Reynaud S, David JP. Deltamethrin and transfluthrin select for distinct transcriptomic responses in the malaria vector Anopheles gambiae. Malar J 2023; 22:256. [PMID: 37667239 PMCID: PMC10476409 DOI: 10.1186/s12936-023-04673-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 08/11/2023] [Indexed: 09/06/2023] Open
Abstract
BACKGROUND The widespread use of pyrethroid insecticides in Africa has led to the development of strong resistance in Anopheles mosquitoes. Introducing new active ingredients can contribute to overcome this phenomenon and ensure the effectiveness of vector control strategies. Transfluthrin is a polyfluorinated pyrethroid whose structural conformation was thought to prevent its metabolism by cytochrome P450 monooxygenases in malaria vectors, thus representing a potential alternative for managing P450-mediated resistance occurring in the field. In this study, a controlled selection was used to compare the dynamics of resistance between transfluthrin and the widely used pyrethroid deltamethrin in the mosquito Anopheles gambiae. Then, the associated molecular mechanisms were investigated using target-site mutation genotyping and RNA-seq. METHODS A field-derived line of An. gambiae carrying resistance alleles at low frequencies was used as starting material for a controlled selection experiment. Adult females were selected across 33 generations with deltamethrin or transfluthrin, resulting in three distinct lines: the Delta-R line (selected with deltamethrin), the Transflu-R line (selected with transfluthrin) and the Tiassale-S line (maintained without selection). Deltamethrin and transfluthrin resistance levels were monitored in each selected line throughout the selection process, as well as the frequency of the L1014F kdr mutation. At generation 17, cross-resistance to other public health insecticides was investigated and transcriptomes were sequenced to compare gene transcription variations and polymorphisms associated with adaptation to each insecticide. RESULTS A rapid increase in resistance to deltamethrin and transfluthrin was observed throughout the selection process in each selected line in association with an increased frequency of the L1014F kdr mutation. Transcriptomic data support a broader response to transfluthrin selection as compared to deltamethrin selection. For instance, multiple detoxification enzymes and cuticle proteins were specifically over-transcribed in the Transflu-R line including the known pyrethroid metabolizers CYP6M2, CYP9K1 and CYP6AA1 together with other genes previously associated with resistance in An. gambiae. CONCLUSION This study confirms that recurrent exposure of adult mosquitoes to pyrethroids in a public health context can rapidly select for various resistance mechanisms. In particular, it indicates that in addition to target site mutations, the polyfluorinated pyrethroid transfluthrin can select for a broad metabolic response, which includes some P450s previously associated to resistance to classical pyrethroids. This unexpected finding highlights the need for an in-depth study on the adaptive response of mosquitoes to newly introduced active ingredients in order to effectively guide and support decision-making programmes in malaria control.
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Affiliation(s)
- Marius Gonse Zoh
- Laboratoire d'Ecologie Alpine (LECA), Grenoble-Alpes University, Savoie Mont-Blanc University, CNRS, 38041, Grenoble, France.
- Vector Control Product Evaluation Centre (VCPEC) Institut Pierre Richet (VCPEC IPR)/INSP, Bouaké, Côte d'Ivoire.
| | - Jean-Marc Bonneville
- Laboratoire d'Ecologie Alpine (LECA), Grenoble-Alpes University, Savoie Mont-Blanc University, CNRS, 38041, Grenoble, France
| | - Frederic Laporte
- Laboratoire d'Ecologie Alpine (LECA), Grenoble-Alpes University, Savoie Mont-Blanc University, CNRS, 38041, Grenoble, France
| | - Jordan Tutagata
- Laboratoire d'Ecologie Alpine (LECA), Grenoble-Alpes University, Savoie Mont-Blanc University, CNRS, 38041, Grenoble, France
| | | | - Behi K Fodjo
- Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
| | | | - Justin McBeath
- Envu, Milton Hall, Ely Road. Milton, Cambridge, CB24 6WZ, UK
| | - Frederic Schmitt
- Envu, 2022 Environmental Science FR S.A.S, 3 Place Giovanni Da Verrazzano, 69009, Lyon, France
| | - Sebastian Horstmann
- Envu, 2022 ES Deutschland GmbH, Alfred-Nobel-Straße 50, 40789, Monheim, Germany
| | - Stéphane Reynaud
- Laboratoire d'Ecologie Alpine (LECA), Grenoble-Alpes University, Savoie Mont-Blanc University, CNRS, 38041, Grenoble, France
| | - Jean-Philippe David
- Laboratoire d'Ecologie Alpine (LECA), Grenoble-Alpes University, Savoie Mont-Blanc University, CNRS, 38041, Grenoble, France
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Yadouleton A, Badou Y, Sanoussi F, Hounkanrin G, Tchibozo C, Adewumi P, Baba-Moussa L. Development of rice farming: a cause of the emergence of multiple insecticide resistance in populations of Anopheles gambiae s.l and its impact on human health in Malanville, Bénin. Malawi Med J 2023; 35:170-176. [PMID: 38362286 PMCID: PMC10865060 DOI: 10.4314/mmj.v35i3.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024] Open
Abstract
Aim The rise in rice production in the district of Malanville, Northen Benin, is a present concern, as it has resulted in the widespread usage of pesticides for crop protection. This could impact human health but also life cycle of Anopheles gambiae, the main vector of malaria. Methods Therefore, insecticide susceptibility bioassays were carried out on populations of An. gambiae s.l aged to 3-5 days old (two from areas where insecticide is highly used and other two areas of low insecticide use) and subjected to insecticide-impregnated papers (Permethrin 0.75%; deltamethrin 0.05%; DDT 4% and bendiocarb 0.1%) following WHO protocol. Polymerase Chain Reactions (PCRs) were used for the detection of Acethlylcholinestrase (Ace-1) and the knock down resistance (kdr) L1014F mutations in An. gambiae populations. Finally, indirect bioassays were conducted for the investigating on the factors affecting the life cycle of An. gambiae due to the use of pesticides. Results An. gambiae from the four sites were resistant to DDT (6 to 8% and 10 to 14% respectively from areas of high and low dose), pyrethroids (22 to 26% and 30 to 36% for permethrin, from areas of high and low dose respectively and 66 to 70% and 72 to 80% for deltamethrin, from high and low dose) but susceptible to carbamate. The kdr L1014F mutation was detected in An. gambiae populations (0.88 to 0.90 and 0.84 to 0.88 from high and low dose, respectively). The ace-1 was detected at low frequencies (<0.002). Bioassays on the impacts of the use of pesticides in the life cycle of An. gambiae showed that soil substrates with pesticides residues have a negative impact on the life cycle eggs of An. gambiae. Conclusion These findings confirmed the negative impacts of pesticides use in rice farming and its impacts on the life cycle of An. gambiae.
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Affiliation(s)
- Anges Yadouleton
- Ecole Normale Supérieure de Natitingou ; Université Nationale des Sciences, Technologies, Ingénierie et Mathématiques (UNSTIM)
- Centre de Recherche Entomologique de Cotonou
- Laboratoire des Fièvres Hémorragiques Virales et des Arbovirus du Bénin
| | - Yvette Badou
- Laboratoire des Fièvres Hémorragiques Virales et des Arbovirus du Bénin
| | - Falilath Sanoussi
- Laboratoire des Fièvres Hémorragiques Virales et des Arbovirus du Bénin
| | - Gildas Hounkanrin
- Laboratoire des Fièvres Hémorragiques Virales et des Arbovirus du Bénin
| | - Carine Tchibozo
- Laboratoire des Fièvres Hémorragiques Virales et des Arbovirus du Bénin
| | - Praise Adewumi
- Laboratoire des Fièvres Hémorragiques Virales et des Arbovirus du Bénin
| | - Lamine Baba-Moussa
- Laboratoire de Biologie et de Typage Moléculaire en Microbiologie/Département de Biochimie et de Biologie Cellulaire/Faculté des Sciences et Techniques/Université d'Abomey-Calavi/ 05 BP 1604 Cotonou, Benin
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11
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Derilus D, Impoinvil LM, Muturi EJ, McAllister J, Kenney J, Massey SE, Hemme R, Kothera L, Lenhart A. Comparative Transcriptomic Analysis of Insecticide-Resistant Aedes aegypti from Puerto Rico Reveals Insecticide-Specific Patterns of Gene Expression. Genes (Basel) 2023; 14:1626. [PMID: 37628677 PMCID: PMC10454789 DOI: 10.3390/genes14081626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 08/04/2023] [Accepted: 08/10/2023] [Indexed: 08/27/2023] Open
Abstract
Aedes aegypti transmits major arboviruses of public health importance, including dengue, chikungunya, Zika, and yellow fever. The use of insecticides represents the cornerstone of vector control; however, insecticide resistance in Ae. aegypti has become widespread. Understanding the molecular basis of insecticide resistance in this species is crucial to design effective resistance management strategies. Here, we applied Illumina RNA-Seq to study the gene expression patterns associated with resistance to three widely used insecticides (malathion, alphacypermethrin, and lambda-cyhalothrin) in Ae. aegypti populations from two sites (Manatí and Isabela) in Puerto Rico (PR). Cytochrome P450s were the most overexpressed detoxification genes across all resistant phenotypes. Some detoxification genes (CYP6Z7, CYP28A5, CYP9J2, CYP6Z6, CYP6BB2, CYP6M9, and two CYP9F2 orthologs) were commonly overexpressed in mosquitoes that survived exposure to all three insecticides (independent of geographical origin) while others including CYP6BY1 (malathion), GSTD1 (alpha-cypermethrin), CYP4H29 and GSTE6 (lambda-cyhalothrin) were uniquely overexpressed in mosquitoes that survived exposure to specific insecticides. The gene ontology (GO) terms associated with monooxygenase, iron binding, and passive transmembrane transporter activities were significantly enriched in four out of six resistant vs. susceptible comparisons while serine protease activity was elevated in all insecticide-resistant groups relative to the susceptible strain. Interestingly, cuticular-related protein genes (chinase and chitin) were predominantly downregulated, which was also confirmed in the functional enrichment analysis. This RNA-Seq analysis presents a detailed picture of the candidate detoxification genes and other pathways that are potentially associated with pyrethroid and organophosphate resistance in Ae. aegypti populations from PR. These results could inform development of novel molecular tools for detection of resistance-associated gene expression in this important arbovirus vector and guide the design and implementation of resistance management strategies.
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Affiliation(s)
- Dieunel Derilus
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA; (L.M.I.); (E.J.M.)
| | - Lucy Mackenzie Impoinvil
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA; (L.M.I.); (E.J.M.)
| | - Ephantus J. Muturi
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA; (L.M.I.); (E.J.M.)
| | - Janet McAllister
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA; (J.M.); (J.K.); (L.K.)
| | - Joan Kenney
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA; (J.M.); (J.K.); (L.K.)
| | - Steven E. Massey
- Biology Department, University of Puerto Rico-Rio Piedras, San Juan, PR 00925, USA;
| | - Ryan Hemme
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, San Juan, PR 00920, USA;
| | - Linda Kothera
- Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA; (J.M.); (J.K.); (L.K.)
| | - Audrey Lenhart
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA; (L.M.I.); (E.J.M.)
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Kouadio FPA, Wipf NC, Nygble AS, Fodjo BK, Sadia CG, Vontas J, Mavridis K, Müller P, Mouhamadou CS. Relationship between insecticide resistance profiles in Anopheles gambiae sensu lato and agricultural practices in Côte d'Ivoire. Parasit Vectors 2023; 16:270. [PMID: 37559080 PMCID: PMC10410919 DOI: 10.1186/s13071-023-05876-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 07/06/2023] [Indexed: 08/11/2023] Open
Abstract
BACKGROUND Insecticide-based malaria vector control is increasingly undermined due to the development of insecticide resistance in mosquitoes. Insecticide resistance may partially be related to the use of pesticides in agriculture, while the level and mechanisms of resistance might differ between agricultural practices. The current study aimed to assess whether phenotypic insecticide resistance and associated molecular resistance mechanisms in Anopheles gambiae sensu lato differ between agricultural practices. METHODS We collected An. gambiae s.l. larvae in six sites with three different agricultural practices, including rice, vegetable and cocoa cultivation. We then exposed the emerging adult females to discriminating concentrations of bendiocarb (0.1%), deltamethrin (0.05%), DDT (4%) and malathion (5%) using the standard World Health Organization insecticide susceptibility test. To investigate underlying molecular mechanisms of resistance, we used multiplex TaqMan qPCR assays. We determined the frequency of target-site mutations, including Vgsc-L995F/S and Vgsc-N1570Y, and Ace1-G280S. In addition, we measured the expression levels of genes previously associated with insecticide resistance in An. gambiae s.l., including the cytochrome P450-dependent monooxygenases CYP4G16, CYP6M2, CYP6P1, CYP6P3, CYP6P4, CYP6Z1 and CYP9K1, and the glutathione S-transferase GSTe2. RESULTS The An. gambiae s.l. populations from all six agricultural sites were resistant to bendiocarb, deltamethrin and DDT, while the populations from the two vegetable cultivation sites were additionally resistant to malathion. Most tested mosquitoes carried at least one mutant Vgsc-L995F allele that is associated with pyrethroid and DDT resistance. In the cocoa cultivation sites, we observed the highest 995F frequencies (80-87%), including a majority of homozygous mutants and several in co-occurrence with the Vgsc-N1570Y mutation. We detected the Ace1 mutation most frequently in vegetable-growing sites (51-60%), at a moderate frequency in rice (20-22%) and rarely in cocoa-growing sites (3-4%). In contrast, CYP6M2, CYP6P3, CYP6P4, CYP6Z1 and CYP9K1, previously associated with metabolic insecticide resistance, showed the highest expression levels in the populations from rice-growing sites compared to the susceptible Kisumu reference strain. CONCLUSION In our study, we observed intriguing associations between the type of agricultural practices and certain insecticide resistance profiles in the malaria vector An. gambiae s.l. which might arise from the use of pesticides deployed for protecting crops.
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Affiliation(s)
- France-Paraudie A Kouadio
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303 Abidjan 01, Abidjan, Côte d'Ivoire.
- Université Nangui Abrogoua, Abidjan, Côte d'Ivoire.
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, CH-4123, Allschwil, Switzerland.
- University of Basel, Petersplatz 1, P.O. Box, CH-4001, Basel, Switzerland.
| | - Nadja C Wipf
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, CH-4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, P.O. Box, CH-4001, Basel, Switzerland
| | | | - Behi K Fodjo
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303 Abidjan 01, Abidjan, Côte d'Ivoire
- Université Nangui Abrogoua, Abidjan, Côte d'Ivoire
| | - Christabelle G Sadia
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303 Abidjan 01, Abidjan, Côte d'Ivoire
- Université Nangui Abrogoua, Abidjan, Côte d'Ivoire
| | - John Vontas
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 70013, Heraklion, Greece
- Pesticide Science Laboratory, Department of Crop Science, Agricultural University of Athens, 11855, Athens, Greece
| | - Konstantinos Mavridis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 70013, Heraklion, Greece
| | - Pie Müller
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, CH-4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, P.O. Box, CH-4001, Basel, Switzerland
| | - Chouaïbou S Mouhamadou
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303 Abidjan 01, Abidjan, Côte d'Ivoire
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13
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Barrera-Illanes AN, Micieli MV, Ibáñez-Shimabukuro M, Santini MS, Martins AJ, Ons S. First report on knockdown resistance mutations in wild populations of Aedes aegypti from Argentina determined by a novel multiplex high-resolution melting polymerase chain reaction method. Parasit Vectors 2023; 16:222. [PMID: 37415215 PMCID: PMC10324241 DOI: 10.1186/s13071-023-05840-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 06/16/2023] [Indexed: 07/08/2023] Open
Abstract
BACKGROUND The mosquito Aedes aegypti is an urban vector of dengue and other arboviruses. During epidemics of these viruses, pyrethroid insecticides are used for the control of adult mosquitoes. The worldwide resistance of Ae. aegypti to these insecticides is a cause of failure of vector control campaigns. The primary target of pyrethroids is the voltage-gated sodium channel. Point mutations in the gene coding for this channel, called knockdown resistance (kdr) mutations, are associated with pyrethroid resistance. Two kdr mutations, V1016I and F1534C, have increased in frequency in natural populations of Ae. aegypti in the Americas during the last decade. Their association with pyrethroid resistance has been largely demonstrated in field populations throughout the Americas, and in in vitro assays. Diagnostics for kdr polymorphism allow early detection of the spread of insecticide resistance, which is critical for timely decisions on vector management. Given the importance of resistance management, high-throughput methods for kdr genotyping are valuable tools as they can be used for resistance monitoring programs. These methods should be cost-effective, to allow regional-scale surveys. Despite the extensive presence of Ae. aegypti and incidence of dengue in Argentina, the presence, abundance, and distribution of kdr mutations in populations of this mosquito have yet to be reported for the country. METHODS Aedes aegypti samples were collected as immature stages or adults from Buenos Aires Metropolitan Area and northern localities of Tartagal (Salta Province) and Calilegua (Jujuy Province). Immature stages were maintained in the laboratory until they developed into adults. A high-resolution melting assay, based on an analysis of melting temperatures, was developed for the simultaneous genotyping of V1016I and F1534C kdr mutations. We used this method to infer the presence and frequencies of kdr alleles in 11 wild populations from Argentina. RESULTS We demonstrated the presence of kdr mutations in Ae. aegypti in Argentina in regions where this species is under different selection pressures due to the use of pyrethroids. The populations under analysis are located in geographically distant regions of the species' distribution in Argentina: the northern provinces of Salta and Jujuy and the Buenos Aires Metropolitan Area. Higher frequencies of resistant-associated alleles were detected in the northern region. We report a multiplex high-throughput assay based on a high-resolution melting polymerase chain reaction method for the simultaneous genotyping of V1016I and F1534C kdr mutations. This assay was shown to be cost-effective, and thus provides an interesting molecular tool for kdr genotyping in A. aegypti control campaigns. CONCLUSIONS We report, to the best of our knowledge for the first time, the presence of kdr mutations in populations of Ae. aegypti from geographically distant locations of Argentina that differ with respect to their epidemiological situation and history of mosquito control. We have developed a high-throughput method for the genotyping of kdr mutations in Ae. aegypti from the Americas. Given its affordability and short running time, this method can be used in control campaigns to monitor the presence and spread of kdr alleles. The information provided here is relevant for the rational design of control strategies in the context of integrated vector management.
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Affiliation(s)
- Alberto N Barrera-Illanes
- Laboratorio de Neurobiología de Insectos (LNI), Centro Regional de Estudios Genómicos, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CENEXA, CONICET, La Plata, Buenos Aires, Argentina
| | - María Victoria Micieli
- Laboratorio de Insectos Vectores, Centro de Estudios Parasitológicos y Vectores (CEPAVE CONICET CCT-La Plata-UNLP), La Plata, Buenos Aires, Argentina
| | - Marina Ibáñez-Shimabukuro
- Laboratorio de Insectos Vectores, Centro de Estudios Parasitológicos y Vectores (CEPAVE CONICET CCT-La Plata-UNLP), La Plata, Buenos Aires, Argentina
| | - María Soledad Santini
- Instituto Nacional de Parasitología "Dr. Mario Fatala Chaben", ANLIS-Malbran, Ministerio de Salud de La Nación, CONICET, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Ademir J Martins
- Laboratório de Fisiologia e Controle de Artrópodes Vetores, Instituto Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil
| | - Sheila Ons
- Laboratorio de Neurobiología de Insectos (LNI), Centro Regional de Estudios Genómicos, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CENEXA, CONICET, La Plata, Buenos Aires, Argentina.
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Taconet P, Zogo B, Soma DD, Ahoua Alou LP, Mouline K, Dabiré RK, Amanan Koffi A, Pennetier C, Moiroux N. Anopheles sampling collections in the health districts of Korhogo (Côte d'Ivoire) and Diébougou (Burkina Faso) between 2016 and 2018. GIGABYTE 2023; 2023:gigabyte83. [PMID: 37408730 PMCID: PMC10318348 DOI: 10.46471/gigabyte.83] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 06/28/2023] [Indexed: 07/07/2023] Open
Abstract
Characterizing the entomological profile of malaria transmission at fine spatiotemporal scales is essential for developing and implementing effective vector control strategies. Here, we present a fine-grained dataset of Anopheles mosquitoes (Diptera: Culicidae) collected in 55 villages of the rural districts of Korhogo (Northern Côte d'Ivoire) and Diébougou (South-West Burkina Faso) between 2016 and 2018. In the framework of a randomized controlled trial, Anopheles mosquitoes were periodically collected by Human Landing Catches experts inside and outside households, and analyzed individually to identify the genus and, for a subsample, species, insecticide resistance genetic mutations, Plasmodium falciparum infection, and parity status. More than 3,000 collection sessions were carried out, achieving about 45,000 h of sampling efforts. Over 60,000 Anopheles were collected (mainly A. gambiae s.s., A. coluzzii, and A. funestus). The dataset is published as a Darwin Core archive in the Global Biodiversity Information Facility, comprising four files: events, occurrences, mosquito characterizations, and environmental data.
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Affiliation(s)
- Paul Taconet
- MIVEGEC, Université de Montpellier, CNRS, IRD, Montpellier, France
| | - Barnabas Zogo
- Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), BP 1500, Bouaké, Côte d’Ivoire
| | - Dieudonné Diloma Soma
- Institut de Recherche en Sciences de la Santé (IRSS), BP 545, Bobo Dioulasso, Burkina Faso
- Institut Supérieur des Sciences de la Santé, Université Nazi Boni, BP 1091, Bobo-Dioulasso, Burkina Faso
| | - Ludovic P. Ahoua Alou
- Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), BP 1500, Bouaké, Côte d’Ivoire
| | - Karine Mouline
- MIVEGEC, Université de Montpellier, CNRS, IRD, Montpellier, France
| | - Roch Kounbobr Dabiré
- Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), BP 1500, Bouaké, Côte d’Ivoire
| | - Alphonsine Amanan Koffi
- Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), BP 1500, Bouaké, Côte d’Ivoire
| | - Cédric Pennetier
- MIVEGEC, Université de Montpellier, CNRS, IRD, Montpellier, France
- Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), BP 1500, Bouaké, Côte d’Ivoire
| | - Nicolas Moiroux
- MIVEGEC, Université de Montpellier, CNRS, IRD, Montpellier, France
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Kouadio FPA, Sika AN, Fodjo BK, Sadia CG, Oyou SK, Ouattara AF, Mouhamadou CS. Phenotypic resistance to pyrethroid associated to metabolic mechanism in Vgsc-L995F-resistant Anopheles gambiae malaria mosquitoes. Wellcome Open Res 2023; 8:118. [PMID: 37396200 PMCID: PMC10308139 DOI: 10.12688/wellcomeopenres.19126.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/21/2023] [Indexed: 07/04/2023] Open
Abstract
Background: The indiscriminate use of insecticides in agriculture and public health lead to a selection of resistance mechanisms in malaria vectors compromising vector control tools and strategies. This study investigated the metabolic response in the Vgsc-L995F Anopheles gambiae Tiassalé resistance strain after long-term exposure of larvae and adults to deltamethrin insecticide. Methods: Vgsc-L995F An. gambiae Tiassalé strain larvae were exposed over 20 generations to deltamethrin (LS) and adults to PermaNet 2.0 (AS) and combining exposure at larvae and adult stages (LAS) and compared to unexposed (NS) group. All four groups were subjected to the standard World Health Organization (WHO) susceptibility tube tests using deltamethrin (0.05%), bendiocarb (0.1%) and malathion (5%). Vgsc-L995F/S knockdown-resistance ( kdr) mutation frequency was screened using multiplex assays based on Taqman real-time polymerase chain reaction (PCR) method. Additionally, expression levels of detoxification enzymes associated to pyrethroid resistance, including CYP4G16, CYP6M2, CYP6P1, CYP6P3, CYP6P4, CYP6Z1 and CYP9K1, and glutathione S-transferase GSTe2 were measured. Results: Our results indicated that deltamethrin resistance was a response to insecticide selection pressure in LS, AS and LAS groups, while susceptibility was observed in NS group. The vectors showed varied mortality rates with bendiocarb and full susceptibility to malathion throughout the selection with LS, AS and LAS groups. Vgsc-L995F mutation stayed at high allelic frequency level in all groups with a frequency between 87% and 100%. Among the overexpressed genes, CYP6P4 gene was the most overexpressed in LS, AS and LAS groups. Conclusion: Long-term exposure of larvae and adults of Vgsc-L995F resistant- An. gambiae Tiassalé strain to deltamethrin and PermaNet 2.0 net induced resistance to deltamethrin under a significant effect of cytochromes P450 detoxification enzymes. These outcomes highlight the necessity of investigating metabolic resistance mechanisms in the target population and not solely kdr resistance mechanisms prior the implementation of vector control strategies for a better impact.
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Affiliation(s)
- France-Paraudie A. Kouadio
- Environment and Health, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, 01 BP 1303 Abidjan 01, Cote d'Ivoire
- Natural Sciences, Université Nangui Abrogoua, Abidjan, 02 BP 801 Abidjan 02, Cote d'Ivoire
| | - Angèle N. Sika
- Natural Sciences, Université Nangui Abrogoua, Abidjan, 02 BP 801 Abidjan 02, Cote d'Ivoire
| | - Behi K. Fodjo
- Environment and Health, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, 01 BP 1303 Abidjan 01, Cote d'Ivoire
- Natural Sciences, Université Nangui Abrogoua, Abidjan, 02 BP 801 Abidjan 02, Cote d'Ivoire
| | - Christabelle G. Sadia
- Environment and Health, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, 01 BP 1303 Abidjan 01, Cote d'Ivoire
- Natural Sciences, Université Nangui Abrogoua, Abidjan, 02 BP 801 Abidjan 02, Cote d'Ivoire
| | - Sébastien K. Oyou
- Environment and Health, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, 01 BP 1303 Abidjan 01, Cote d'Ivoire
| | - Allassane F. Ouattara
- Environment and Health, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, 01 BP 1303 Abidjan 01, Cote d'Ivoire
- Natural Sciences, Université Nangui Abrogoua, Abidjan, 02 BP 801 Abidjan 02, Cote d'Ivoire
| | - Chouaïbou S. Mouhamadou
- Environment and Health, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Abidjan, 01 BP 1303 Abidjan 01, Cote d'Ivoire
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16
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Kouadio FPA, Sika AN, Fodjo BK, Sadia CG, Oyou SK, Ouattara AF, Mouhamadou CS. Phenotypic resistance to pyrethroid associated to metabolic mechanism in Vgsc-L995F-resistant Anopheles gambiae malaria mosquitoes. Wellcome Open Res 2023. [DOI: 10.12688/wellcomeopenres.19126.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2023] Open
Abstract
Background: The indiscriminate use of insecticides in agriculture and public health lead to a selection of resistance mechanisms in malaria vectors compromising vector control tools and strategies. This study investigated the metabolic response in the Vgsc-L995F Anopheles gambiae Tiassalé resistance strain after long-term exposure of larvae and adults to deltamethrin insecticide. Methods: We exposed, over 20 generations, Vgsc-L995F An. gambiae Tiassalé strain larvae to deltamethrin (LS) and adults to PermaNet 2.0 (AS) and combining exposure at larvae and adult stages (LAS) and compared to unexposed (NS) group. All four groups were subjected to the standard World Health Organization (WHO) susceptibility tube tests using deltamethrin (0.05%), bendiocarb (0.1%) and malathion (5%). Vgsc-L995F/S knockdown-resistance (kdr) mutation frequency was screened using multiplex assays based on Taqman real-time polymerase chain reaction (PCR) method. Additionally, expression levels of detoxification enzymes associated to pyrethroid resistance, including CYP4G16, CYP6M2, CYP6P1, CYP6P3, CYP6P4, CYP6Z1 and CYP9K1, and glutathione S-transferase GSTe2 were measured. Results: Our results indicated that deltamethrin resistance was a response to insecticide selection pressure in LS, AS and LAS groups, while susceptibility was observed in NS group. The vectors showed varied mortality rates with bendiocarb and full susceptibility to malathion throughout the selection with LS, AS and LAS groups. Vgsc-L995F mutation stayed at high allelic frequency level in all groups with a frequency between 87% and 100%. Among the overexpressed genes, CYP6P4 gene was the most overexpressed in LS, AS and LAS groups. Conclusion: Long-term exposure of larvae and adults of Vgsc-L995F resistant-An. gambiae Tiassalé strain to deltamethrin and PermaNet 2.0 net induced resistance to deltamethrin under a significant effect of cytochromes P450 detoxification enzymes. These outcomes highlight the necessity of investigating metabolic resistance mechanisms in the target population and not solely kdr resistance mechanisms prior the implementation of vector control strategies for a better impact.
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Perugini E, Guelbeogo WM, Guglielmo F, Poggi C, Gabrieli E, Ranson H, Della Torre A, Pombi M. The interplay between malaria vectors and human activity accounts for high residual malaria transmission in a Burkina Faso village with universal ITN coverage. Parasit Vectors 2023; 16:101. [PMID: 36922855 PMCID: PMC10015820 DOI: 10.1186/s13071-023-05710-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 02/22/2023] [Indexed: 03/17/2023] Open
Abstract
BACKGROUND Mosquito and human behaviour interaction is a key determinant of the maximum level of protection against malaria that can be provided by insecticide-treated nets (ITNs). Nevertheless, scant literature focuses on this interaction, overlooking a fundamental factor for efficient malaria control. This study aims to estimate malaria transmission risk in a Burkina Faso village by integrating vector biting rhythms with some key information about human habits. METHODS Indoor/outdoor human landing catches were conducted for 16 h (16:00-08:00) during 8 nights (September 2020) in Goden village. A survey about net usage and sleeping patterns was submitted to half the households (October-December 2020). A subsample of collected specimens of Anopheles gambiae sensu lato was molecularly processed for species identification, Plasmodium detection from heads-thoraxes and L1014F pyrethroid-resistance allele genotyping. Hourly mosquito abundance was statistically assessed by GLM/GAM, and the entomological inoculation rate (EIR) was corrected for the actual ITN usage retrieved from the questionnaire. RESULTS Malaria transmission was mainly driven by Anopheles coluzzii (68.7%) followed by A. arabiensis (26.2%). The overall sporozoite rate was 2% with L1014F estimated frequency of 0.68 (N = 1070 out of 15,201 A. gambiae s.l. collected). No major shift in mosquito biting rhythms in response to ITN or differences between indoor and outdoor catches were detected. Impressive high biting pressure (mean 30.3 mosquitoes/person/hour) was exerted from 20:00 to 06:00 with a peak at 4:00. Human survey revealed that nearly all inhabitants were awake before 20:00 and after 7:00 and at least 8.7% had no access to bednets. Adjusting for anthropological data, the EIR dropped from 6.7 to 1.2 infective bites/person/16 h. In a scenario of full net coverage and accounting only for the human sleeping patterns, the daily malaria transmission risk not targetable by ITNs was 0.69 infective bites. CONCLUSIONS The high mosquito densities and interplay between human/vector activities means that an estimated 10% of residual malaria transmission cannot be prevented by ITNs in the village. Locally tailored studies, like the current one, are essential to explore the heterogeneity of human exposure to infective bites and, consequently, to instruct the adoption of new vector control tools strengthening individual and community protection.
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Affiliation(s)
- Eleonora Perugini
- Department of Public Health and Infectious Diseases, Sapienza University, Rome, Italy
| | - Wamdaogo M Guelbeogo
- Centre National de Recherche et Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Federica Guglielmo
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Cristiana Poggi
- Department of Public Health and Infectious Diseases, Sapienza University, Rome, Italy
| | - Eugenio Gabrieli
- Department of Public Health and Infectious Diseases, Sapienza University, Rome, Italy
| | - Hilary Ranson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | | | - Marco Pombi
- Department of Public Health and Infectious Diseases, Sapienza University, Rome, Italy.
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18
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Das S, Máquina M, Phillips K, Cuamba N, Marrenjo D, Saúte F, Paaijmans KP, Huijben S. Fine-scale spatial distribution of deltamethrin resistance and population structure of Anopheles funestus and Anopheles arabiensis populations in Southern Mozambique. Malar J 2023; 22:94. [PMID: 36915131 PMCID: PMC10010967 DOI: 10.1186/s12936-023-04522-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 03/03/2023] [Indexed: 03/16/2023] Open
Abstract
BACKGROUND Insecticide resistance in malaria vectors can be spatially highly heterogeneous, yet population structure analyses frequently find relatively high levels of gene flow among mosquito populations. Few studies have contemporaneously assessed phenotypic, genotypic and population structure analysis on mosquito populations and none at fine geographical scales. In this study, genetic diversity, population structure, and insecticide resistance profiles of Anopheles funestus and Anopheles arabiensis were examined across mosquito populations from and within neighbouring villages. METHODS Mosquitoes were collected from 11 towns in southern Mozambique, as well as from different neighbourhoods within the town of Palmeira, during the peak malaria transmission season in 2016. CDC bottle bioassay and PCR assays were performed with Anopheles mosquitoes at each site to determine phenotypic and molecular insecticide resistance profiles, respectively. Microsatellite analysis was conducted on a subsample of mosquitoes to estimate genetic diversity and population structure. RESULTS Phenotypic insecticide resistance to deltamethrin was observed in An. funestus sensu stricto (s.s.) throughout the area, though a high level of mortality variation was seen. However, 98% of An. funestus s.s. were CYP6P9a homozygous resistant. An. arabiensis was phenotypically susceptible to deltamethrin and 99% were kdr homozygous susceptible. Both Anopheles species exhibited high allelic richness and heterozygosity. Significant deviations from Hardy-Weinberg equilibrium were observed, and high linkage disequilibrium was seen for An. funestus s.s., supporting population subdivision. However, the FST values were low for both anophelines (- 0.00457 to 0.04213), Nm values were high (9.4-71.8 migrants per generation), AMOVA results showed almost 100% genetic variation among and within individuals, and Structure analysis showed no clustering of An. funestus s.s. and An. arabiensis populations. These results suggest high gene flow among mosquito populations. CONCLUSION Despite a relatively high level of phenotypic variation in the An. funestus population, molecular analysis shows the population is admixed. These data indicate that CYP6P9a resistance markers do not capture all phenotypic variation in the area, but also that resistance genes of high impact are likely to easily spread in the area. Conversely, other strategies, such as transgenic mosquito release programmes will likely not face challenges in this locality.
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Affiliation(s)
- Smita Das
- The Center for Evolution & Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, USA
- PATH, Seattle, WA, USA
| | - Mara Máquina
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Manhica, Mozambique
| | - Keeley Phillips
- The Center for Evolution & Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Nelson Cuamba
- Programa Nacional de Controlo da Malária, Ministério da Saúde, Maputo, Mozambique
- PMI VectorLink Project, Abt Associates Inc., Maputo, Mozambique
| | - Dulcisaria Marrenjo
- Programa Nacional de Controlo da Malária, Ministério da Saúde, Maputo, Mozambique
| | - Francisco Saúte
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Manhica, Mozambique
| | - Krijn P Paaijmans
- The Center for Evolution & Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, USA
- Simon A. Levin Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ, USA
- The Biodesign Center for Immunotherapy, Vaccines and Virotherapy, Arizona State University, Tempe, AZ, USA
- ISGlobal, Barcelona, Spain
| | - Silvie Huijben
- The Center for Evolution & Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, USA.
- Simon A. Levin Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ, USA.
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N'Dri BP, Wipf NC, Saric J, Fodjo BK, Raso G, Utzinger J, Müller P, Mouhamadou CS. Species composition and insecticide resistance in malaria vectors in Ellibou, southern Côte d'Ivoire and first finding of Anopheles arabiensis in Côte d'Ivoire. Malar J 2023; 22:93. [PMID: 36915098 PMCID: PMC10010045 DOI: 10.1186/s12936-023-04456-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 01/16/2023] [Indexed: 03/16/2023] Open
Abstract
BACKGROUND Knowing the species composition and insecticide resistance status of the target vector population is important to guide malaria vector control. The aim of this study was to characterize the malaria vector population in terms of species composition, insecticide susceptibility status and potential underlying resistance mechanisms in Ellibou, southern Côte d'Ivoire. METHODS A 1-year longitudinal entomological survey was conducted using light traps and pyrethroid spray catches to sample adult mosquitoes in combination with larval sampling. The susceptibility status of Anopheles gambiae sensu lato (s.l.) to bendiocarb, deltamethrin, DDT and malathion was assessed using the World Health Organization insecticide susceptibility test. Additionally, An. gambiae specimens were screened for knockdown (kdr) and acetylcholineesterase (ace1) target site resistance alleles, and the expression levels of eight metabolic resistance genes, including seven cytochrome P450 monooxygenases (P450s) and one glutathione S-transferase (GST), measured with reverse transcription quantitative real-time polymerase chain reaction (qPCR). RESULTS Overall, 2383 adult mosquitoes from 12 different taxa were collected with Culex quinquefasciatus and An. gambiae being the predominant taxa. Molecular identification of An. gambiae s.l. revealed the presence of Anopheles arabiensis, Anopheles coluzzii, An. gambiae sensu stricto (s.s.) and Anopheles coluzzii/An. gambiae s.s. hybrids. Anopheles gambiae mosquitoes were resistant to all insecticides except malathion. PCR diagnostics revealed the presence of ace1-G280S and the kdr L995F, L995S and N1570Y target-site mutations. Additionally, several genes were upregulated, including five P450s (i.e., CYP6P3, CYP6M2, CYP9K1, CYP6Z1, CYP6P1) and GSTE2. CONCLUSION This is the first documented presence of An. arabiensis in Côte d'Ivoire. Its detection - together with a recent finding further north of the country - confirms its existence in the country, which is an early warning sign, as An. arabiensis shows a different biology than the currently documented malaria vectors. Because the local An. gambiae population was still susceptible to malathion, upregulation of P450s, conferring insecticide resistance to pyrethroids, together with the presence of ace1, suggest negative cross-resistance. Therefore, organophosphates could be an alternative insecticide class for indoor residual spraying in the Ellibou area, while additional tools against the outdoor biting An. arabiensis will have to be considered.
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Affiliation(s)
- Bédjou P N'Dri
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire. .,Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland. .,University of Basel, 4001, Basel, Switzerland.
| | - Nadja C Wipf
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland.,University of Basel, 4001, Basel, Switzerland
| | - Jasmina Saric
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland.,University of Basel, 4001, Basel, Switzerland
| | - Behi K Fodjo
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire
| | - Giovanna Raso
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland.,University of Basel, 4001, Basel, Switzerland
| | - Jürg Utzinger
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland.,University of Basel, 4001, Basel, Switzerland
| | - Pie Müller
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland.,University of Basel, 4001, Basel, Switzerland
| | - Chouaïbou S Mouhamadou
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire.,North Carolina State University, Raleigh, NC, 27695-7508, USA
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Kouamé RM, Lynd A, Kouamé JK, Vavassori L, Abo K, Donnelly MJ, Edi C, Lucas E. Widespread occurrence of copy number variants and fixation of pyrethroid target site resistance in Anopheles gambiae ( s.l.) from southern Côte d'Ivoire. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2023; 3:100117. [PMID: 36970448 PMCID: PMC10031352 DOI: 10.1016/j.crpvbd.2023.100117] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 02/09/2023] [Accepted: 02/21/2023] [Indexed: 03/07/2023]
Abstract
Resistance to pyrethroid and organophosphate insecticides in the malaria vector Anopheles gambiae (s.l.) is conferred by a variety of genetic mutations, including single nucleotide polymorphisms (SNPs) and copy number variants (CNVs). Knowledge of the distribution of these mutations in mosquito populations is a prerequisite for establishing better strategies for their management. In this study, a total of 755 Anopheles gambiae (s.l.) from southern Côte d'Ivoire were exposed to deltamethrin or pirimiphos-methyl insecticides and were screened to assess the distribution of SNPs and CNVs known or believed to confer resistance to one or other of the insecticide classes. Most individuals from the An. gambiae (s.l.) complex were identified by molecular tests as Anopheles coluzzii. Survival to deltamethrin (from 94% to 97%) was higher than to pirimiphos-methyl (from 10% to 49%). In An. gambiae (s.s.), the SNP in the Voltage Gated Sodium Channel (Vgsc) at the 995F locus (Vgsc-995F) was fixed, while other target site mutations were rare or absent (Vgsc-402L: 0%; Vgsc-1570Y: 0%, Acetylcholinesterase Acel-280S: 14%). In An. coluzzii, Vgsc-995F was the target site SNP found at highest frequency (65%) followed by other target site mutations (Vgsc-402L: 36%; Vgsc-1570Y: 0.33%; Acel-280S: 45%). The Vgsc-995S SNP was not present. The presence of the Ace1-280S SNP was found to be significantly linked to the presence of the Ace1-CNV, Ace1_AgDup. Significant association was found between the presence of the Ace1_AgDup and pirimiphos-methyl resistance in An. gambiae (s.s.) but not in An. coluzzii. The deletion Ace1_Del97 was found in one specimen of An. gambiae (s.s.). Four CNVs in the Cyp6aa/Cyp6p gene cluster, which contains genes of known importance for resistance, were detected in An. coluzzii, the most frequent being Dup 7 (42%) and Dup 14 (26%). While none of these individual CNV alleles were significantly associated with resistance, copy number in the Cyp6aa gene region in general was associated with increased resistance to deltamethrin. Elevated expression of Cyp6p3 was nearly associated with deltamethrin resistance, although there was no association of resistance with copy number. Use of alternative insecticides and control methods to arrest resistance spread in An. coluzzii populations is merited.
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Affiliation(s)
- Ruth M.A. Kouamé
- Institut National Polytechnique Félix Houphouët Boigny, BP 1093, Yamoussoukro, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, 01 BP 1303 Abidjan 01, Côte d’Ivoire
| | - Amy Lynd
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Jackson K.I. Kouamé
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, 01 BP 1303 Abidjan 01, Côte d’Ivoire
- Université Nangui Abrogoua, 02 BP 801 Abidjan 02, Côte d’Ivoire
| | - Laura Vavassori
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, 01 BP 1303 Abidjan 01, Côte d’Ivoire
- Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Kouabénan Abo
- Institut National Polytechnique Félix Houphouët Boigny, BP 1093, Yamoussoukro, Côte d’Ivoire
| | - Martin J. Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Constant Edi
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, 01 BP 1303 Abidjan 01, Côte d’Ivoire
| | - Eric Lucas
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
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21
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Mbewe NJ, Kirby MJ, Snetselaar J, Kaaya RD, Small G, Azizi S, Ezekia K, Manunda B, Shirima B, Mosha FW, Rowland MW. A non-inferiority and GLP-compliant study of broflanilide IRS (VECTRON™ T500), a novel meta-diamide insecticide against Anopheles arabiensis. FRONTIERS IN TROPICAL DISEASES 2023. [DOI: 10.3389/fitd.2023.1126869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Management of insecticide resistance in vector control requires development and evaluation of active ingredients (AIs) with new modes of action. VECTRON™ T500 is a wettable powder formulation used for Indoor Residual Spraying (IRS) containing 50% of broflanilide as an AI. This study evaluated the efficacy of VECTRON™ T500 sprayed on blocks of different substrates (concrete, mud and plywood) against pyrethroid susceptible and resistant Anopheles gambiae sensu stricto (s.s.) strains, and wild An. arabiensis. It also assessed the efficacy of VECTRON™ T500 in experimental huts plastered with mud and concrete against wild free-flying An. arabiensis; and non-inferiority to a World Health Organization listed indoor residual spraying product Actellic® 300CS in terms of mortality in Moshi, Tanzania.Monthly cone bioassays on blocks and in experimental huts (against pyrethroid susceptible and resistant An. gambiae s.s.) were conducted over a 12-month period after spraying of VECTRON™ T500 and Actellic® CS300. Collections of wild free-flying An. arabiensis were also done in the sprayed huts. The main outcome for cone bioassays was mortality while for the wild hut trial collections, it was mortality and blood feeding inhibition. Grouped logistic regressions with random effects were used to analyse all dichotomous outcome variables from wild collections.The results showed residual efficacy of VECTRON™ T500 of at least 80% mortality was longest on concrete, followed by plywood and then mud substrates for all mosquito strains. Furthermore, VECTRON™ T500 significantly increased the likelihood of mortality (OR:> 1.37, P<0.001) in wild collections of An. arabiensis compared to Actellic® 300CS. Blood feeding was not significantly different in the wild collection of An. arabiensis between VECTRON™ T500 and Actellic® 300CS arms.These results show that VECTRON™ T500 is efficacious against pyrethroid-resistant An. gambiae s.s. and non-inferior to Actellic® 300CS. Therefore, it should be an important addition to the current arsenal of insecticides used for insecticide resistance management and vector control.
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22
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Joseph Matiya D, Philbert AB, Kidima WB, Matowo JJ. The Effect of Plasmodium falciparum (Welch) (Haemospororida: Plasmodiidae) Infection on the Susceptibility of Anopheles gambiae s.l. and Anopheles funestus (Diptera: Culicidae) to Pyrethroid Insecticides in the North-Western and South-Eastern, Tanzania. JOURNAL OF MEDICAL ENTOMOLOGY 2023; 60:112-121. [PMID: 36287642 DOI: 10.1093/jme/tjac163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Indexed: 06/16/2023]
Abstract
The rapid development of insecticide resistance in malaria vectors threatens insecticide-based interventions. It is hypothesized that infection of insecticide-resistant vectors with Plasmodium parasites increases their vulnerability to insecticides, thus assuring the effectiveness of insecticide-based strategies for malaria control. Nonetheless, there is limited field data to support this. We investigated the effect of the Plasmodium falciparum infection on the susceptibility of Anopheles gambiae s.l. and Anopheles funestus to pyrethroids in south-eastern (Kilombero) and north-western (Muleba), Tanzania. The wild-collected mosquitoes were tested against 0.05% deltamethrin and 0.75% permethrin, then assessed for sporozoite rate and resistant gene (kdr) mutations. All Anopheles gambiae s.l. from Kilombero were An. arabiensis (Patton, 1905) while those from Muleba were 87% An. gambiae s.s (Giles, 1902) and 13% An. Arabiensis. High levels of pyrethroid resistance were observed in both areas studied. The kdr mutation was only detected in An. gambiae s.s. at the frequency of 100% in survivors and 97% in dead mosquitoes. The P. falciparum sporozoite rates were slightly higher in susceptible than in resistant mosquitoes. In Muleba, sporozoite rates in An. gambiae s.l. were 8.1% and 6.4% in dead mosquitoes and survivors, respectively (SRR = 1.28, p = 0.19). The sporozoite rates in Kilombero were 1.3% and 0.7% in the dead and survived mosquitoes, respectively (sporozoite rate ratio (SRR) = 1.9, p = 0.33). In An. funestus group sporozoite rates were 6.2% and 4.4% in dead and survived mosquitoes, respectively (SRR = 1.4, p = 0.54). These findings indicate that insecticides might still be effective in malaria control despite the rapid development of insecticide resistance in malaria vectors.
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Affiliation(s)
- Deokary Joseph Matiya
- Dar es Salaam University College of Education (DUCE), PO Box 2329, Dar es Salaam, Tanzania
- University of Dar es Salaam (UDSM), PO Box 35064, Dar es Salaam, Tanzania
| | - Anitha B Philbert
- University of Dar es Salaam (UDSM), PO Box 35064, Dar es Salaam, Tanzania
| | - Winifrida B Kidima
- University of Dar es Salaam (UDSM), PO Box 35064, Dar es Salaam, Tanzania
| | - Johnson J Matowo
- Kilimanjaro Christian Medical University College (KCMUCo), PO Box 2240, Moshi, Tanzania
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23
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Fotso-Toguem Y, Tene-Fossog B, Mugenzi LMJ, Wondji MJ, Njiokou F, Ranson H, Wondji CS. Genetic Diversity of Cytochrome P450s CYP6M2 and CYP6P4 Associated with Pyrethroid Resistance in the Major Malaria Vectors Anopheles coluzzii and Anopheles gambiae from Yaoundé, Cameroon. Genes (Basel) 2022; 14:52. [PMID: 36672793 PMCID: PMC9858699 DOI: 10.3390/genes14010052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/14/2022] [Accepted: 12/19/2022] [Indexed: 12/28/2022] Open
Abstract
Assessing the genetic diversity of metabolic resistance genes, such as cytochrome P450s, helps to understand the dynamics and evolution of resistance in the field. Here, we analyzed the polymorphisms of CYP6M2 and CYP6P4, associated with pyrethroid resistance in Anopheles coluzzii and Anopheles gambiae, to detect potential resistance markers. Field-caught resistant mosquitos and susceptible lab strains were crossed, and F4 was exposed to permethrin for 15 min and 90 min to discriminate highly susceptible (HS) and highly resistant (HR) mosquitos, respectively. Significant permethrin mortality reduction was observed after pre-exposure to PBO, suggesting the gene involvement of P450s. qPCR analysis revealed significant overexpression of CYP6M2 (FC = 19.57 [95% CI 13.96-25.18] for An. coluzzii; 10.16 [7.86-12.46] for An. gambiae) and CYP6P4 (FC = 6.73 [6.15-7.30] An. coluzzii; 23.62 [26.48-20.76] An. gambiae). Full-gene and ≈1 kb upstream were sequenced. For CYP6M2, the upstream region shows low diversity in HR and HS (overall Hd = 0.49, π = 0.018), whereas the full-gene shows allelic-variation but without evidence of ongoing selection. CYP6P4 upstream region showed a lower diversity in HR (Hd = 0.48) than HS (Hd = 0.86) of An. gambiae. These results highlighted that CYP6P4-associated resistance is potentially driven by modification in upstream region. However, further work is needed to determine the real causative variants that will help design rapid detection tools.
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Affiliation(s)
- Yvan Fotso-Toguem
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé P.O. Box 812, Cameroon
| | - Billy Tene-Fossog
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon
| | - Leon M. J. Mugenzi
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon
| | - Murielle J. Wondji
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L35QA, UK
| | - Flobert Njiokou
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé P.O. Box 812, Cameroon
| | - Hilary Ranson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L35QA, UK
| | - Charles S. Wondji
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L35QA, UK
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Azizi S, Matowo J, Mbewe NJ, Protopopoff N, Athumani R, Matiku W, Shayo M, Tenu F, Rowland M, Mosha F, Kitau J. Laboratory and semi-field efficacy evaluation of permethrin-piperonyl butoxide treated blankets against pyrethroid-resistant malaria vectors. Sci Rep 2022; 12:22166. [PMID: 36550139 PMCID: PMC9774072 DOI: 10.1038/s41598-022-26804-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022] Open
Abstract
To control pyrethroid-resistant malaria vectors, Indoor Residual Spraying (IRS) and Long-Lasting Insecticidal Nets (LLINs) that include additional ingredients to pyrethroid are being developed. Same progress needs to be made to the pyrethroid-treated blankets, which are more compatible with shelter structures found in emergency settings such as displaced populations. In the current study, efficacy of blankets treated with permethrin and piperonyl butoxide (PBO) was evaluated against pyrethroid-resistant Anopheles gambiae sensu stricto. Efficacy was compared with that of Olyset LLIN, Olyset Plus LLIN and untreated blanket in terms of mortality and blood-feeding inhibition against pyrethroid-resistant Anopheles gambiae mosquitoes. The current study indicates that, in emergency shelters such as migrant and refugee camps where LLINs cannot be used, PBO-permethrin blankets may provide protection against resistant mosquitoes if widely used. No side effects related to the use of the treated blankets were reported from the participants. These results need validation in a large-scale field trial to assess the epidemiological impact of the intervention, durability and acceptability of this new vector control strategy for malaria vector control.
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Affiliation(s)
- Salum Azizi
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania.
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania.
| | - Johnson Matowo
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Njelembo Joshua Mbewe
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
- Department of Disease Control, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Natacha Protopopoff
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
- Department of Disease Control, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Rashid Athumani
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Wambura Matiku
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Magreth Shayo
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Filemoni Tenu
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Mark Rowland
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
- Department of Disease Control, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Franklin Mosha
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Jovin Kitau
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- World Health Organization, Country Office, P.O. Box 9292, Dar es Salaam, Tanzania
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25
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Ahmed M, Nath NS, Hugo LE, Devine GJ, Macdonald J, Pollak NM. Rapid detection of kdr mutation F1534C in Aedes aegypti using recombinase polymerase amplification and lateral flow dipsticks. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2022; 187:105209. [PMID: 36127073 DOI: 10.1016/j.pestbp.2022.105209] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 07/19/2022] [Accepted: 08/08/2022] [Indexed: 06/15/2023]
Abstract
Insecticide resistance monitoring is essential in assessing the efficacy of vector control measures. However, gold standard PCR-based molecular analyses for insecticide resistance detection are often hindered by time-consuming sample processing, as well as considerable infrastructure and resourcing requirements. In this study, we combined a novel one-step sample preparation reagent with a rapid isothermal molecular test that detects a knock down resistance (kdr) mutation (F1534C) that enables pyrethroid resistance in Aedes aegypti mosquitoes. We trialled the rapid F1534C pyrethroid resistance test using insecticide resistant Ae. aegypti mosquito bodies and compared results to a conventional, allele-specific quantitative PCR (AS-qPCR) coupled with melt curve genotyping in corresponding mosquito heads. From a strain of Ae. aegypti established from an insecticide resistant population in Merida, Mexico (n = 27), all the mosquito bodies (n = 27) tested positive with the rapid F1534C test regardless of whether they were homozygous or heterozygous. To assess diagnostic test specificity, we confirmed that F1534 was not detected in laboratory-reared, fully susceptible Ae. aegypti mosquito bodies (n = 28) using the rapid F1534C test or the conventional AS-qPCR melt curve analysis. All corresponding mosquito heads (n = 28) were homozygous wild-type FF1534. The rapid F1534C test thus demonstrated 100% diagnostic sensitivity (95% CI: 87.23% to 100%) and 100% diagnostic specificity (95% CI: 87.66% to 100.00%) for detection of the F1534C pyrethroid resistant single nucleotide polymorphism (SNP) in both heterozygous and homozygous Ae. aegypti. In the collection of mutant mosquitoes from Mexico, CC1534 homozygous mutants occurred at a frequency of 74.1% (n = 20) and FC heterozygous mutants at a frequency of 25.9% (n = 7). The rapid F1534C test significantly reduced the sample processing and testing time from approximately 6 h for the AS-qPCR melt curve analysis to only 25 min. These results demonstrate significant potential for our approach to resistance testing as a field-based, low-resource, rapid alternative to time-consuming and expensive laboratory-based detection.
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Affiliation(s)
- Madeeha Ahmed
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia; School of Science and Engineering, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia.
| | - Nisa Suraj Nath
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, 300 Herston Road, 4006 Herston, QLD, Australia.
| | - Leon E Hugo
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, 300 Herston Road, 4006 Herston, QLD, Australia.
| | - Gregor J Devine
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, 300 Herston Road, 4006 Herston, QLD, Australia.
| | - Joanne Macdonald
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia; School of Science and Engineering, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia.
| | - Nina M Pollak
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia; School of Science and Engineering, University of the Sunshine Coast, Sippy Downs, QLD 4556, Australia.
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26
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Fournet F, Adja AM, Adou KA, Dahoui MMC, Coulibaly B, Assouho KF, Zoh DD, Koné M, Koné A, Niamien KL, Cornelie S, Tia E, Moiroux N. First detection of the malaria vector Anopheles arabiensis in Côte d'Ivoire: urbanization in question. Malar J 2022; 21:275. [PMID: 36171572 PMCID: PMC9520799 DOI: 10.1186/s12936-022-04295-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 09/15/2022] [Indexed: 12/03/2022] Open
Abstract
Background Previous studies have revealed high malaria transmission in Bouaké, Côte d’Ivoire. The sociopolitical crisis in the country and the resulting environmental changes have raised the need to update existing knowledge on mosquito vector species and malaria transmission. Methods Adult mosquitoes were caught using the human landing catch (HLC) sampling method in Bouaké. They were collected in six districts representative of the diversity in urban landscapes. Sampling points were selected along the water network crossing the city and monitored from 2020 to 2021 to detect the presence of anopheline larvae. PCR techniques were used to ascertain the species of the Anopheles gambiae complex, Plasmodium falciparum sporozoite infection in a subset of Anopheles vectors, and insecticide resistance mechanisms in Anopheles arabiensis only. Results A total of 4599 Anopheles mosquitoes were collected and then identified. Anopheles gambiae sensu lato (s.l.) made up the majority of the whole collection (99%) while Anopheles funestus (0.7%), Anopheles ziemanni (0.2%), Anopheles pharoensis (0.2%) represented the remaining proportion of collection. Among the Anopheles gambiae complex, three species were identified namely An. gambiae sensu stricto (45.9%), Anopheles coluzzii (52.2%), and Anopheles arabiensis (1.9%). The first two species had already been collected in Bouaké, however this is the first time that An. arabiensis is reported in Côte d’Ivoire. Anopheles arabiensis was also collected during the larval surveys in a similar proportion (1.1%) in the same areas as the adults. Conclusions This study detected the presence of An. arabiensis for the first time in Côte d’Ivoire. This species was found quite far from its usual geographic area and its expansion could be linked to the urbanization process. Although no An. arabiensis was found to be infected by Plasmodium sp., its role in malaria transmission in Bouaké has to be explored, particularly since its exophagic behaviour raises the issue of control measures and the use of insecticide-impregnated nets. The spread of this species in Côte d'Ivoire should be assessed through further research in additional towns in the country.
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Affiliation(s)
- Florence Fournet
- MIVEGEC (Université de Montpellier, CNRS, IRD), Montpellier, France. .,Centre d'Entomologie Médicale Et Vétérinaire, Bouaké, Côte d'Ivoire. .,Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire.
| | - Akre M Adja
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire.,Unité de Formation Et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d'Ivoire
| | - Kouassi A Adou
- MIVEGEC (Université de Montpellier, CNRS, IRD), Montpellier, France.,Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire.,Institut de Géographie Tropicale, Université Félix Houphouët-Boigny, Abidjan, Côte d'Ivoire
| | - Milossé M C Dahoui
- MIVEGEC (Université de Montpellier, CNRS, IRD), Montpellier, France.,Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire
| | - Baba Coulibaly
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire
| | - Konan F Assouho
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire.,Unité de Formation Et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d'Ivoire
| | - Dounin D Zoh
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire.,Unité de Formation Et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d'Ivoire
| | - Moussa Koné
- Centre d'Entomologie Médicale Et Vétérinaire, Bouaké, Côte d'Ivoire
| | - Aboubacar Koné
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire
| | - Koffi L Niamien
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire
| | - Sylvie Cornelie
- MIVEGEC (Université de Montpellier, CNRS, IRD), Montpellier, France
| | - Emmanuel Tia
- Centre d'Entomologie Médicale Et Vétérinaire, Bouaké, Côte d'Ivoire
| | - Nicolas Moiroux
- MIVEGEC (Université de Montpellier, CNRS, IRD), Montpellier, France
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27
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Tene‐Fossog B, Fotso‐Toguem YG, Amvongo‐Adjia N, Ranson H, Wondji CS. Temporal variation of high-level pyrethroid resistance in the major malaria vector Anopheles gambiae s.l. in Yaoundé, Cameroon, is mediated by target-site and metabolic resistance. MEDICAL AND VETERINARY ENTOMOLOGY 2022; 36:247-259. [PMID: 35521949 PMCID: PMC9545389 DOI: 10.1111/mve.12577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 04/11/2022] [Indexed: 06/14/2023]
Abstract
Constant assessment of insecticide resistance levels is mandatory to implement adequate malaria control tools, but little information is available on the annual dynamics of resistance. We, therefore, monitored variations in resistance in Anopheles gambiae s.l. over four seasons during 2 years in two localities of Yaoundé: urban Etoa-Meki and peri-urban Nkolondom. Mosquitoes were collected seasonally at larval stage and reared to adults for insecticide susceptibility tests and molecular analysis of resistance mechanisms. Anopheles coluzzii was found in Etoa-Meki and An. gambiae in Nkolondom. Low mortalities to pyrethroids were observed (permethrin <10%, deltamethrin <21%), and resistance extended to 5× and 10× diagnostic doses, revealing a marked increase compared to previous studies. A seasonal variation in resistance was observed with the highest levels within dry seasons in Etoa-Meki and rainy seasons in Nkolondom. The 1014F kdr allele shows a high frequency (0.9), associated with overexpression of metabolic genes (Cyp6M2, Cyp6P4, Cyp9K1, Cyp6Z1, and Cyp6Z2) varying significantly seasonally. This study reveals an escalation in resistance to pyrethroids in Yaoundé's malaria vectors with seasonal variations. An adequate choice of the implementation period of punctual vector control actions according to the resistance profile will help to potentiate the desired effect and thus improve its efficiency.
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Affiliation(s)
- Billy Tene‐Fossog
- Department of Medical EntomologyCentre for Research in Infectious Diseases (CRID)YaoundéCameroon
| | - Yvan Gaetan Fotso‐Toguem
- Department of Medical EntomologyCentre for Research in Infectious Diseases (CRID)YaoundéCameroon
- Department of Animal Biology and Physiology, Faculty of ScienceUniversity of Yaoundé 1YaoundéCameroon
| | - Nathalie Amvongo‐Adjia
- Department of Medical EntomologyCentre for Research in Infectious Diseases (CRID)YaoundéCameroon
- Medical Research CentreInstitute of Medical Research and Medicinal Plants Studies (IMPM)YaoundéCameroon
| | - Hilary Ranson
- Department of Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
| | - Charles S. Wondji
- Department of Medical EntomologyCentre for Research in Infectious Diseases (CRID)YaoundéCameroon
- Department of Vector BiologyLiverpool School of Tropical MedicineLiverpoolUK
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Ngongang-Yipmo ES, Tchouakui M, Menze BD, Mugenzi LMJ, Njiokou F, Wondji CS. Reduced performance of community bednets against pyrethroid-resistant Anopheles funestus and Anopheles gambiae, major malaria vectors in Cameroon. Parasit Vectors 2022; 15:230. [PMID: 35754045 PMCID: PMC9233849 DOI: 10.1186/s13071-022-05335-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 05/23/2022] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Long-lasting insecticidal nets (LLINs) are a vital tool in the fight against malaria vectors. However, their efficacy in the field can be impacted by several factors, including patterns of usage, net age, mosquito resistance and the delayed mortality effect, all of which could influence malaria transmission. We have investigated the effectiveness of the various brands of LLINs available in markets and households in Cameroon on pyrethroid-resistant mosquitoes and assessed their post-exposure effect. METHODS Following quality control assessment on a susceptible laboratory mosquito strain, we evaluated the immediate and delayed mortality effects of exposure to LLINs (both newly bough LLINst and used ones collected from households in Elende village, Cameroon, in 2019) using standard WHO cone tests on Anopheles gambiae and Anopheles funestus populations collected from the Centre region of Cameroon. Alive female mosquitoes were genotyped for various resistance markers at different time points post-exposure to evaluate the impact of insecticide resistance on the efficacy of bednets. RESULTS The laboratory-susceptible strain experienced high mortality rates when exposed to all pyrethroid-only brands of purchased nets (Olyset® Net, Super Net, PermaNet® 2.0, Yorkool®, Royal Sentry®) (Mean±SEM: 68.66 ± 8.35% to 93.33 ± 2.90%). However, low mortality was observed among wild An. funestus mosquitoes exposed to the bednets (0 ± 0 to 28 ± 6.7%), indicating a reduced performance of these nets against field mosquitoes. Bednets collected from households also showed reduced efficacy on the laboratory strain (mortality: 19-66%), as well as displaying a significant loss of efficacy against the local wild strains (mortality: 0 ± 0% to 4 ± 2.6% for An. gambiae sensu lato and 0 ± 0% to 8 ± 3.2% for An. funestus). However, compared to the unexposed group, mosquitoes exposed to bednets showed a significantly reduced longevity, indicating that the efficacy of these nets was not completely lost. Mosquitoes with the CYP6P9a-RR and L119F-GSTe2 mutations conferring pyrethroid resistance showed greater longevity after exposure to the Olyset net than their susceptible counterparts, indicating the impact of resistance on bednet efficacy and delayed mortality. CONCLUSION These findings show that although standard bednets drastically lose their efficacy against pyrethroid-resistant field mosquitoes, they still are able to induce delayed mortality in exposed populations. The results of this study also provide evidence of the actual impact of resistance on the quality and efficacy of LLINs in use in the community, with mosquitoes carrying the CYP6P9a-RR and L119F-GSTe2 mutations conferring pyrethroid resistance living longer than their susceptible counterparts. These results highlight the need to use new-generation nets that do not rely solely on pyrethroids.
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Affiliation(s)
- Emilie S. Ngongang-Yipmo
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon
- Parasitology and Ecology Laboratory, Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon
| | - Magellan Tchouakui
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon
- Parasitology and Ecology Laboratory, Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon
| | - Benjamin D. Menze
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L35QA UK
| | - Leon M. J. Mugenzi
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon
- Department of Biochemistry and Molecular Biology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon
| | - Flobert Njiokou
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon
- Parasitology and Ecology Laboratory, Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon
| | - Charles S. Wondji
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L35QA UK
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Boussougou-Sambe ST, Woldearegai TG, Doumba-Ndalembouly AG, Ngossanga B, Mba RB, Edoa JR, Zinsou JF, Honkpehedji YJ, Ngoa UA, Dejon-Agobé JC, Borrmann S, Kremsner PG, Mordmüller B, Adegnika AA. Assessment of malaria transmission intensity and insecticide resistance mechanisms in three rural areas of the Moyen Ogooué Province of Gabon. Parasit Vectors 2022; 15:217. [PMID: 35725630 PMCID: PMC9208124 DOI: 10.1186/s13071-022-05320-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 05/10/2022] [Indexed: 12/03/2022] Open
Abstract
Background Vector control is considered to be the most successful component of malaria prevention programs and a major contributor to the reduction of malaria incidence over the last two decades. However, the success of this strategy is threatened by the development of resistance to insecticides and behavioural adaptations of vectors. The aim of this study was to monitor malaria transmission and the distribution of insecticide resistance genes in Anopheles populations from three rural areas of the Moyen Ogooué Province of Gabon. Methods Anopheles spp. were collected using human landing catches in Bindo, Nombakélé and Zilé, three villages located in the surroundings of Lambaréné, during both the rainy and dry seasons. Mosquitoes were identified morphologically, and DNA was extracted from heads and thoraces. Members of the Anopheles gambiae complex were identified by molecular methods using the PCR SINE200 protocol and by sequencing of the internal transcribed spacer 2 region. Taqman assays were used to determine Plasmodium infection and the presence of resistance alleles. Results Anopheles gambiae sensu lato (97.7%), An. moucheti (1.7%) and An. coustani (0.6%) were the three groups of species collected. Anopheles gambiae sensu stricto (98.5%) and An. coluzzii (1.5%) were the only species of the An. gambiae complex present in the collection. Of the 1235 Anopheles collected, 1193 were collected during the rainy season; these exhibited an exophagic behaviour, and consistently more mosquitoes were collected outdoor than indoor in the three study areas. Of the 1166 Anopheles screened, 26 (2.2%) were infected with Plasmodium species, specifically Plasmodium falciparum (66.7%), P. malariae (15.4%), P. ovale curtisi (11.5%) and P. ovale wallikeri (3.8%). Malaria transmission intensity was high in Zilé, with an average annual entomological inoculation rate (aEIR) of 243 infective bites per year, while aEIRs in Bindo and Nombakélé were 80.2 and 17 infective bites per year, respectively. Both the L1014F and L1014S mutations were present at frequencies > 95% but no Ace1G119S mutation was found. Conclusion Our results demonstrate that malaria transmission intensity is heterogeneous in these three rural areas of Moyen Ogooué Province, with areas of high transmission, such as Zilé. The exophagic behaviour of the mosquitoes as well as the high frequency of resistance mutations are serious challenges that need to be addressed by the deployment of control measures adapted to the local setting. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-022-05320-9.
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Affiliation(s)
| | - Tamirat Gebru Woldearegai
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon.,Institut für Tropenmedizin, Eberhard Karls Universität, Tübingen, Germany.,German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
| | | | | | - Romuald Beh Mba
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
| | | | - Jeannot Fréjus Zinsou
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon.,Department of Parasitology, Leiden University Medical Center, Leiden, the Netherlands
| | - Yabo Josiane Honkpehedji
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon.,Department of Parasitology, Leiden University Medical Center, Leiden, the Netherlands.,Fondation pour la Recherche Scientifique (FORS), Cotonou, Benin
| | | | - Jean Claude Dejon-Agobé
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon.,Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Division of Internal Medicine, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, the Netherlands
| | - Steffen Borrmann
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon.,Institut für Tropenmedizin, Eberhard Karls Universität, Tübingen, Germany
| | - Peter G Kremsner
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon.,Institut für Tropenmedizin, Eberhard Karls Universität, Tübingen, Germany.,German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
| | - Benjamin Mordmüller
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon.,Institut für Tropenmedizin, Eberhard Karls Universität, Tübingen, Germany.,Department of Medical Microbiology, Radboud University Medical Center (UMC), 6524 GA, Nijmegen, The Netherlands
| | - Ayôla A Adegnika
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon.,Institut für Tropenmedizin, Eberhard Karls Universität, Tübingen, Germany.,German Center for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany.,Fondation pour la Recherche Scientifique (FORS), Cotonou, Benin
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30
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Wolie RZ, Koffi AA, Ayuk-Taylor L, Alou LPA, Sternberg ED, N'Nan-Alla O, N'Guessan Y, Dahounto A, Oumbouke WA, Tia IZ, N'Guetta SPA, Cook J, Thomas MB, N'Guessan R. Entomological indicators of malaria transmission prior to a cluster-randomized controlled trial of a 'lethal house lure' intervention in central Côte d'Ivoire. Malar J 2022; 21:188. [PMID: 35705981 PMCID: PMC9202144 DOI: 10.1186/s12936-022-04196-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 05/21/2022] [Indexed: 11/16/2022] Open
Abstract
Background A study was conducted prior to implementing a cluster-randomized controlled trial (CRT) of a lethal house lure strategy in central Côte d’Ivoire to provide baseline information on malaria indicators in 40 villages across five health districts. Methods Human landing catches (HLC) were performed between November and December 2016, capturing mosquitoes indoors and outdoors between 18.00 and 08.00 h. Mosquitoes were processed for entomological indicators of malaria transmission (human biting, parity, sporozoite, and entomological inoculation rates (EIR)). Species composition and allelic frequencies of kdr-w and ace-1R mutations were also investigated within the Anopheles gambiae complex. Results Overall, 15,632 mosquitoes were captured. Anopheles gambiae sensu lato (s.l.) and Anopheles funestus were the two malaria vectors found during the survey period, with predominance for An. gambiae (66.2%) compared to An. funestus (10.3%). The mean biting rate for An. gambiae was almost five times higher than that for An. funestus (19.8 bites per person per night for An. gambiae vs 4.3 bites per person per night for An. funestus) and this was evident indoors and outdoors. Anopheles funestus was more competent to transmit malaria parasites in the study area, despite relatively lower number tested for sporozoite index (4.14% (63/1521) for An. gambiae vs 8.01% (59/736) for An. funestus; χ2 = 12.216; P < 0.0001). There were no significant differences between the proportions infected outdoors and indoors for An. gambiae (4.03 vs 4.13%; χ2 = 0.011; P = 0.9197) and for An. funestus (7.89 vs 8.16%; χ2 = 2.58e−29; P = 1). The majority of both infected vectors with malaria parasites harboured Plasmodium falciparum (93.65% for An. gambiae and 98. 31% for An. funestus). Overall, the EIR range for both species in the different districts appeared to be high (0.35–2.20 infected bites per human per night) with the highest value observed in the district of North-Eastern-Bouaké. There were no significant differences between transmission occurring outdoor and indoor for both species. Of the An. gambiae s.l. analysed, only An. gambiae sensu stricto (14.1%) and Anopheles coluzzii (85.9%) were found. The allelic frequencies of kdr and ace-1R were higher in An. gambiae (0.97 for kdr and 0.19 for ace-1R) than in An. coluzzii (0.86 for kdr and 0.10 for ace-1R) (P < 0.001). Conclusion Despite universal coverage with long-lasting insecticidal nets (LLINs) in the area, there was an abundance of the malaria vectors (An. gambiae and An. funestus) in the study area in central Côte d’Ivoire. Consistent with high insecticide resistance intensity previously detected in these districts, the current study detected high kdr frequency (> 85%), coupled with high malaria transmission pattern, which could guide the use of Eave tubes in the study areas.
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Affiliation(s)
- Rosine Z Wolie
- Unité de Recherche Et de Pédagogie de Génétique, Université Félix Houphouët-Boigny, UFR Biosciences, Abidjan, Côte d'Ivoire. .,Vector Control Product Evaluation Centre-Institut Pierre Richet (VCPEC-IPR), Institut Pierre Richet (IPR), Bouaké, Côte d'Ivoire. .,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire.
| | - Alphonsine A Koffi
- Vector Control Product Evaluation Centre-Institut Pierre Richet (VCPEC-IPR), Institut Pierre Richet (IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | | | - Ludovic P Ahoua Alou
- Vector Control Product Evaluation Centre-Institut Pierre Richet (VCPEC-IPR), Institut Pierre Richet (IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Eleanore D Sternberg
- Department of Entomology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Oulo N'Nan-Alla
- Unité de Recherche Et de Pédagogie de Génétique, Université Félix Houphouët-Boigny, UFR Biosciences, Abidjan, Côte d'Ivoire
| | - Yao N'Guessan
- Vector Control Product Evaluation Centre-Institut Pierre Richet (VCPEC-IPR), Institut Pierre Richet (IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Amal Dahounto
- Vector Control Product Evaluation Centre-Institut Pierre Richet (VCPEC-IPR), Institut Pierre Richet (IPR), Bouaké, Côte d'Ivoire
| | - Welbeck A Oumbouke
- Vector Control Product Evaluation Centre-Institut Pierre Richet (VCPEC-IPR), Institut Pierre Richet (IPR), Bouaké, Côte d'Ivoire.,Innovative Vector Control Consortium, IVCC, Liverpool, UK
| | - Innocent Z Tia
- Vector Control Product Evaluation Centre-Institut Pierre Richet (VCPEC-IPR), Institut Pierre Richet (IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire.,Université Alassane Ouattara, Bouaké, Côte d'Ivoire
| | - Simon-Pierre A N'Guetta
- Unité de Recherche Et de Pédagogie de Génétique, Université Félix Houphouët-Boigny, UFR Biosciences, Abidjan, Côte d'Ivoire
| | - Jackie Cook
- Department of Infectious Disease Epidemiology, International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Matthew B Thomas
- Department of Entomology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA.,York Environmental Sustainability Institute, University of York, York, UK
| | - Raphael N'Guessan
- Vector Control Product Evaluation Centre-Institut Pierre Richet (VCPEC-IPR), Institut Pierre Richet (IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire.,Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
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Azizi S, Snetselaar J, Kaaya R, Matowo J, Onen H, Shayo M, Kisengwa E, Tilya E, Manunda B, Mawa B, Mosha F, Kirby M. Implementing OECD GLP principles for the evaluation of novel vector control tools: a case study with two novel LLINs, SafeNet ® and SafeNet NF ®. Malar J 2022; 21:183. [PMID: 35690824 PMCID: PMC9188019 DOI: 10.1186/s12936-022-04208-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 05/30/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND To sustain high universal Long-Lasting Insecticidal Nets (LLINs) coverage, affordable nets that provide equivalent or better protection than standard LLINs, are required. Test facilities evaluating new LLINs require compliance to Good Laboratory Practice (GLP) standards to ensure the quality and integrity of test data. Following GLP principles allows for the reconstruction of activities during the conduct of a study and minimizes duplication of efficacy testing. This case study evaluated the efficacy of two LLINs: SafeNet NF® and SafeNet® LLIN. METHODS The study was conducted according to GLP principles and followed World Health Organization guidelines for evaluating LLINs. The LLINs were assessed in experimental huts against wild, pyrethroid-resistant Anopheles arabiensis mosquitoes. Nets were either unwashed or washed 20 times and artificially holed to simulate a used torn net. Blood-feeding inhibition and mortality were compared with a positive control (Interceptor® LLIN) and an untreated net. RESULTS Mosquito entry in the huts was reduced compared to negative control for the unwashed SafeNet NF, washed Safenet LLIN and the positive control arms. Similar exiting rates were found for all the treatment arms. Significant blood-feeding inhibition was only found for the positive control, both when washed and unwashed. All insecticide treatments induced significantly higher mortality compared to an untreated net. Compared to the positive control, the washed and unwashed SafeNet NF® resulted in similar mortality. For the SafeNet® LLINs the unwashed net had an equivalent performance, but the mortality for the washed net was significantly lower than the positive control. Internal audits of the study confirmed that all critical phases complied with Standard Operating Procedures (SOPs) and the study plan. The external audit confirmed that the study complied with GLP standards. CONCLUSIONS SafeNet NF® and SafeNet® LLIN offered equivalent protection to the positive control (Interceptor® LLIN). However, further research is needed to investigate the durability, acceptability, and residual efficacy of these nets in the community. This study demonstrated that GLP-compliant evaluation of LLINs can be successfully conducted by African research institutions.
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Affiliation(s)
- Salum Azizi
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, 255, Tanzania. .,Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, 255, Tanzania.
| | - Janneke Snetselaar
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, 255, Tanzania.,Innovative Vector Control Consortium (IVCC), Liverpool, L3 5QA, UK.,London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Robert Kaaya
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, 255, Tanzania.,Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, 255, Tanzania
| | - Johnson Matowo
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, 255, Tanzania.,Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, 255, Tanzania
| | - Hudson Onen
- Department of Zoology, Entomology and Fisheries Sciences, College of Natural Sciences, School of Biosciences, Makerere University, P.O. Box 7062, Kampala, Uganda
| | - Magreth Shayo
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, 255, Tanzania.,Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, 255, Tanzania
| | - Ezekia Kisengwa
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, 255, Tanzania.,Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, 255, Tanzania
| | - Evod Tilya
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, 255, Tanzania.,Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, 255, Tanzania
| | - Baltazari Manunda
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, 255, Tanzania.,Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, 255, Tanzania
| | - Benson Mawa
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, 255, Tanzania.,Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, 255, Tanzania
| | - Franklin Mosha
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, 255, Tanzania.,Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, 255, Tanzania
| | - Matthew Kirby
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, 255, Tanzania.,Innovative Vector Control Consortium (IVCC), Liverpool, L3 5QA, UK
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Menze BD, Mugenzi LMJ, Tchouakui M, Wondji MJ, Tchoupo M, Wondji CS. Experimental Hut Trials Reveal That CYP6P9a/b P450 Alleles Are Reducing the Efficacy of Pyrethroid-Only Olyset Net against the Malaria Vector Anopheles funestus but PBO-Based Olyset Plus Net Remains Effective. Pathogens 2022; 11:pathogens11060638. [PMID: 35745492 PMCID: PMC9228255 DOI: 10.3390/pathogens11060638] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 05/12/2022] [Accepted: 05/19/2022] [Indexed: 02/04/2023] Open
Abstract
Malaria remains a major public health concern in Africa. Metabolic resistance in major malaria vectors such as An. funestus is jeopardizing the effectiveness of long-lasting insecticidal nets (LLINs) to control malaria. Here, we used experimental hut trials (EHTs) to investigate the impact of cytochrome P450-based resistance on the efficacy of PBO-based net (Olyset Plus) compared to a permethrin-only net (Olyset), revealing a greater loss of efficacy for the latter. EHT performed with progenies of F5 crossing between the An. funestus pyrethroid-resistant strain FUMOZ and the pyrethroid-susceptible strain FANG revealed that PBO-based nets (Olyset Plus) induced a significantly higher mortality rate (99.1%) than pyrethroid-only nets (Olyset) (56.7%) (p < 0.0001). The blood-feeding rate was higher in Olyset compared to Olyset Plus (11.6% vs. 5.6%; p = 0.013). Genotyping the CYP6P9a/b and the intergenic 6.5 kb structural variant (SV) resistance alleles showed that, for both nets, homozygote-resistant mosquitoes have a greater ability to blood-feed than the susceptible mosquitoes. Homozygote-resistant genotypes significantly survived more with Olyset after cone assays (e.g., CYP6P9a OR = 34.6; p < 0.0001) than homozygote-susceptible mosquitoes. A similar but lower correlation was seen with Olyset Plus (OR = 6.4; p < 0.001). Genotyping EHT samples confirmed that CYP6P9a/b and 6.5 kb_SV homozygote-resistant mosquitoes survive and blood-feed significantly better than homozygote-susceptible mosquitoes when exposed to Olyset. Our findings highlight the negative impact of P450-based resistance on pyrethroid-only nets, further supporting that PBO nets, such as Olyset Plus, are a better solution in areas of P450-mediated resistance to pyrethroids.
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Affiliation(s)
- Benjamin D. Menze
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK;
- Medical Entomology Department, Centre for Research in Infectious Diseases (CRID), Yaoundé 13591, Cameroon; (L.M.J.M.); (M.T.); (M.T.)
- Correspondence: (B.D.M.); (C.S.W.)
| | - Leon M. J. Mugenzi
- Medical Entomology Department, Centre for Research in Infectious Diseases (CRID), Yaoundé 13591, Cameroon; (L.M.J.M.); (M.T.); (M.T.)
| | - Magellan Tchouakui
- Medical Entomology Department, Centre for Research in Infectious Diseases (CRID), Yaoundé 13591, Cameroon; (L.M.J.M.); (M.T.); (M.T.)
| | - Murielle J. Wondji
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK;
- Medical Entomology Department, Centre for Research in Infectious Diseases (CRID), Yaoundé 13591, Cameroon; (L.M.J.M.); (M.T.); (M.T.)
| | - Micareme Tchoupo
- Medical Entomology Department, Centre for Research in Infectious Diseases (CRID), Yaoundé 13591, Cameroon; (L.M.J.M.); (M.T.); (M.T.)
| | - Charles S. Wondji
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK;
- Medical Entomology Department, Centre for Research in Infectious Diseases (CRID), Yaoundé 13591, Cameroon; (L.M.J.M.); (M.T.); (M.T.)
- Correspondence: (B.D.M.); (C.S.W.)
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Diurnal biting of malaria mosquitoes in the Central African Republic indicates residual transmission may be "out of control". Proc Natl Acad Sci U S A 2022; 119:e2104282119. [PMID: 35576470 PMCID: PMC9173762 DOI: 10.1073/pnas.2104282119] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Transmission of malarial parasites occurs via the bites of Anopheles mosquitoes, whose blood-feeding behavior modulates the risk of infection. In many malaria endemic regions, eradication strategies rely on reducing transmission by targeting nocturnal blood-feeding Anopheles with insecticidal nets. However, a proportion of mosquitoes may naturally feed when humans are not protected by nets, setting a ceiling to the efficacy of massive net-based interventions. In Bangui, Central African Republic, 20 to 30% of daily exposure to indoor bites occurs during daytime, and this fraction may correspond to mosquitoes escaping exposure to current vector control measures. Knowledge about the daily rhythmicity of mosquito biting is therefore crucial to adjust vector control tactics to protect people at places where they spend daytime. Malaria control interventions target nocturnal feeding of the Anopheles vectors indoors to reduce parasite transmission. Mass deployment of insecticidal bed nets and indoor residual spraying with insecticides, however, may induce mosquitoes to blood-feed at places and at times when humans are not protected. These changes can set a ceiling to the efficacy of these control interventions, resulting in residual malaria transmission. Despite its relevance for disease transmission, the daily rhythmicity of Anopheles biting behavior is poorly documented, most investigations focusing on crepuscular hours and nighttime. By performing mosquito collections 48-h around the clock, both indoors and outdoors, and by modeling biting events using circular statistics, we evaluated the full daily rhythmicity of biting in urban Bangui, Central African Republic. While the bulk of biting by Anopheles gambiae, Anopheles coluzzii, Anopheles funestus, and Anopheles pharoensis occurred from sunset to sunrise outdoors, unexpectedly ∼20 to 30% of indoor biting occurred during daytime. As biting events did not fully conform to any family of circular distributions, we fitted mixtures of von Mises distributions and found that observations were consistent with three compartments, corresponding indoors to populations of early-night, late-night, and daytime-biting events. It is not known whether these populations of biting events correspond to spatiotemporal heterogeneities or also to distinct mosquito genotypes/phenotypes belonging consistently to each compartment. Prevalence of Plasmodium falciparum in nighttime- and daytime-biting mosquitoes was the same. As >50% of biting occurs in Bangui when people are unprotected, malaria control interventions outside the domiciliary environment should be envisaged.
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Sympatric Populations of the Anopheles gambiae Complex in Southwest Burkina Faso Evolve Multiple Diverse Resistance Mechanisms in Response to Intense Selection Pressure with Pyrethroids. INSECTS 2022; 13:insects13030247. [PMID: 35323544 PMCID: PMC8955173 DOI: 10.3390/insects13030247] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/16/2022] [Accepted: 02/21/2022] [Indexed: 02/01/2023]
Abstract
Simple Summary Targeting mosquitoes with insecticides is one of the most effective methods to prevent malaria transmission. Although numbers of malaria cases have declined substantially this century, this pattern is not universal and Burkina Faso has one of the highest burdens of malaria; it is also a hotspot for the evolution of insecticide resistance in malaria vectors. We have established laboratory colonies from multiple species within the An. gambiae complex, the most efficient group of malaria vectors in the world, from larval collections in southwest Burkina Faso. Using bioassays with different insecticides widely used to control public health pests, we provide a profile of insecticide resistance in each of these colonies and, using molecular tools, reveal the genetic changes underpinning this resistance. We show that, whilst many resistance mechanisms are shared between species, there are some important differences which may affect resistance to current and future insecticide classes. The complexity, and diversity of resistance mechanisms highlights the importance of screening any potential new insecticide intended for use in malaria control against a wide range of populations. These stable laboratory colonies provide a valuable resource for insecticide discovery, and for further studies on the evolution and dispersal of insecticide resistance within and between species. Abstract Pyrethroid resistance in the Anopheles vectors of malaria is driving an urgent search for new insecticides that can be used in proven vector control tools such as insecticide treated nets (ITNs). Screening for potential new insecticides requires access to stable colonies of the predominant vector species that contain the major pyrethroid resistance mechanisms circulating in wild populations. Southwest Burkina Faso is an apparent hotspot for the emergence of pyrethroid resistance in species of the Anopheles gambiae complex. We established stable colonies from larval collections across this region and characterised the resistance phenotype and underpinning genetic mechanisms. Three additional colonies were successfully established (1 An. coluzzii, 1 An. gambiae and 1 An. arabiensis) to add to the 2 An. coluzzii colonies already established from this region; all 5 strains are highly resistant to pyrethroids. Synergism assays found that piperonyl butoxide (PBO) exposure was unable to fully restore susceptibility although exposure to a commercial ITN containing PBO resulted in 100% mortality. All colonies contained resistant alleles of the voltage gated sodium channel but with differing proportions of alternative resistant haplotypes. RNAseq data confirmed the role of P450s, with CYP6P3 and CYP6Z2 elevated in all 5 strains, and identified many other resistance mechanisms, some found across strains, others unique to a particular species. These strains represent an important resource for insecticide discovery and provide further insights into the complex genetic changes driving pyrethroid resistance.
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Tungu PK, Rowland MW, Messenger LA, Small GJ, Bradley J, Snetselaar J, Kirby MJ, Mbewe NJ. Large-scale (Phase III) evaluation of broflanilide 50WP (VECTRON™ T500) for indoor residual spraying for malaria vector control in Northeast Tanzania: study protocol for a two-arm, non-inferiority, cluster-randomised community trial. BMC Infect Dis 2022; 22:171. [PMID: 35189830 PMCID: PMC8862469 DOI: 10.1186/s12879-022-07138-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 02/09/2022] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Indoor residual spraying (IRS) is a major method of malaria vector control across sub-Saharan Africa. Effective control is being undermined by the rapid spread of insecticide resistance. There is major investment in development of new insecticides for IRS that possess novel modes of action, long residual activity, low mammalian toxicity and minimal cross-resistance. VECTRON™ T500, a new IRS product containing the active ingredient broflanilide as a 50% wettable powder (WP), has been shown to be efficacious against pyrethroid susceptible and resistant vector species on mud and concrete substrates in experimental hut (Phase II) trials. METHODS A two-arm non-inferiority cluster randomized controlled trial (Phase III) will be undertaken in Muheza District, Tanga Region, Tanzania. VECTRON™ T500 will be compared to the IRS product Fludora® Fusion (clothianidin 50% WP + deltamethrin 6.25% WP). The predominant malaria vectors in the study area are pyrethroid-resistant Anopheles gambiae s.s., An. arabiensis and An. funestus s.s. Sixteen village clusters will be pair-matched on baseline vector densities and allocated to reference and intervention arms. Consenting households in the intervention arm will be sprayed with VECTRON™ T500 and those in the reference arm will be sprayed with Fludora® Fusion. Each month, CDC light traps will collect mosquitoes to estimate changes in vector density, indoor biting, sporozoite and entomological inoculation rates (EIR). Susceptibility to IRS active ingredients will be assessed using World Health Organisation (WHO) bottle bioassays. Target site and metabolic resistance mechanisms will be characterised among Anopheles field populations from both trial arms. Residual efficacy of both IRS products will be monitored for 12 months post intervention. Questionnaire and focus group discussions will explore factors that influence adherence, adverse effects and benefits of IRS. DISCUSSION This protocol describes a large-scale non-inferiority evaluation of a novel IRS product to reduce the density and EIR of pyrethroid-resistant Anopheles vectors. If VECTRON™ T500 proves non-inferior to Fludora® Fusion, it will be considered as an additional vector control product for malaria prevention and insecticide resistance management. TRIAL REGISTRATION ClinicalTrials.gov, NCT05150808, registered on 26 November 2021. Retrospectively registered.
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Affiliation(s)
- Patrick K Tungu
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK.,National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania
| | - Mark W Rowland
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK.
| | - Louisa A Messenger
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | | | - John Bradley
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Janneke Snetselaar
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK.,Innovative Vector Control Consortium, Liverpool, UK
| | - Matthew J Kirby
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK.,Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Njelembo J Mbewe
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK.,Kilimanjaro Christian Medical University College, Moshi, Tanzania
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Multi-insecticide resistant malaria vectors in the field remain susceptible to malathion, despite the presence of Ace1 point mutations. PLoS Genet 2022; 18:e1009963. [PMID: 35143477 PMCID: PMC8830663 DOI: 10.1371/journal.pgen.1009963] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 11/23/2021] [Indexed: 12/13/2022] Open
Abstract
Insecticide resistance in Anopheles mosquitoes is seriously threatening the success of insecticide-based malaria vector control. Surveillance of insecticide resistance in mosquito populations and identifying the underlying mechanisms enables optimisation of vector control strategies. Here, we investigated the molecular mechanisms of insecticide resistance in three Anopheles coluzzii field populations from southern Côte d’Ivoire, including Agboville, Dabou and Tiassalé. All three populations were resistant to bendiocarb, deltamethrin and DDT, but not or only very weakly resistant to malathion. The absence of malathion resistance is an unexpected result because we found the acetylcholinesterase mutation Ace1-G280S at high frequencies, which would typically confer cross-resistance to carbamates and organophosphates, including malathion. Notably, Tiassalé was the most susceptible population to malathion while being the most resistant one to the pyrethroid deltamethrin. The resistance ratio to deltamethrin between Tiassalé and the laboratory reference colony was 1,800 fold. By sequencing the transcriptome of individual mosquitoes, we found numerous cytochrome P450-dependent monooxygenases – including CYP6M2, CYP6P2, CYP6P3, CYP6P4 and CYP6P5 – overexpressed in all three field populations. This could be an indication for negative cross-resistance caused by overexpression of pyrethroid-detoxifying cytochrome P450s that may activate pro-insecticides, thereby increasing malathion susceptibility. In addition to the P450s, we found several overexpressed carboxylesterases, glutathione S-transferases and other candidates putatively involved in insecticide resistance. Insecticide-based mosquito control has saved millions of lives from malaria and other vector-borne diseases. However, the emergence and increase of insecticide resistant Anopheles populations seriously threaten to derail malaria control programmes. Surveillance of insecticide resistance and understanding the underlying molecular mechanisms are key for choosing effective vector control strategies. Here, we characterised the degree and mechanisms of resistance in three malaria vector populations from Côte d’Ivoire. Our key finding was that these multi-insecticide resistant malaria vectors largely remained susceptible to malathion, despite the presence of a mutation in the target enzyme of this organophosphate insecticide that would typically confer resistance. Intriguingly, we found overexpression of metabolic P450 enzymes that are known to detoxify insecticides and activate pro-insecticides such as malathion. It is highly probable that, here, we observed P450-mediated negative cross-resistance for the first time in Anopheles field populations. Negative cross-resistance merits further investigation as advantage could be taken of this phenomenon in the fight against multi-resistant malaria vectors.
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Matowo J, Weetman D, Pignatelli P, Wright A, Charlwood JD, Kaaya R, Shirima B, Moshi O, Lukole E, Mosha J, Manjurano A, Mosha F, Rowland M, Protopopoff N. Expression of pyrethroid metabolizing P450 enzymes characterizes highly resistant Anopheles vector species targeted by successful deployment of PBO-treated bednets in Tanzania. PLoS One 2022; 17:e0249440. [PMID: 35073324 PMCID: PMC8786186 DOI: 10.1371/journal.pone.0249440] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 12/20/2021] [Indexed: 11/18/2022] Open
Abstract
Long lasting insecticidal nets (LLINs) are a proven tool to reduce malaria transmission, but in Africa efficacy is being reduced by pyrethroid resistance in the major vectors. A previous study that was conducted in Muleba district, Tanzania indicated possible involvement of cytochrome P450 monooxygenases in a pyrethroid resistance in An. gambiae population where pre-exposure to piperonyl butoxide (PBO) followed by permethrin exposure in CDC bottle bioassays led to partial restoration of susceptibility. PBO is a synergist that can block pyrethroid-metabolizing enzymes in a mosquito. Insecticide resistance profiles and underlying mechanisms were investigated in Anopheles gambiae and An. funestus from Muleba during a cluster randomized trial. Diagnostic dose bioassays using permethrin, together with intensity assays, suggest pyrethroid resistance that is both strong and very common, but not extreme. Transcriptomic analysis found multiple P450 genes over expressed including CYP6M2, CYP6Z3, CYP6P3, CYP6P4, CYP6AA1 and CYP9K1 in An. gambiae and CYP6N1, CYP6M7, CYP6M1 and CYP6Z1 in An. funestus. Indeed, very similar suites of P450 enzymes commonly associated with resistant populations elsewhere in Africa were detected as over expressed suggesting a convergence of mechanisms across Sub-Saharan African malaria vectors. The findings give insight into factors that may correlate with pyrethroid PBO LLIN success, broadly supporting model predictions, but revision to guidelines previously issued by the World Health Organization is warranted.
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Affiliation(s)
- Johnson Matowo
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
- * E-mail:
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Patricia Pignatelli
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Alexandra Wright
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Jacques D. Charlwood
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Robert Kaaya
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Boniface Shirima
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Oliva Moshi
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Eliud Lukole
- Department of Parasitology, National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - Jacklin Mosha
- Department of Parasitology, National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - Alphaxard Manjurano
- Department of Parasitology, National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - Franklin Mosha
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Mark Rowland
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Natacha Protopopoff
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
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Gansané A, Candrinho B, Mbituyumuremyi A, Uhomoibhi P, NFalé S, Mohammed AB, Guelbeogo WM, Sanou A, Kangoye D, Debe S, Kagone M, Hakizimana E, Uwimana A, Tuyishime A, Ingabire CM, Singirankabo JH, Koenker H, Marrenjo D, Abilio AP, Salvador C, Savaio B, Okoko OO, Maikore I, Obi E, Awolola ST, Adeogun A, Babarinde D, Ali O, Guglielmo F, Yukich J, Scates S, Sherrard-Smith E, Churcher T, Fornadel C, Shannon J, Kawakyu N, Beylerian E, Digre P, Tynuv K, Gogue C, Mwesigwa J, Wagman J, Adeleke M, Adeolu AT, Robertson M. Design and methods for a quasi-experimental pilot study to evaluate the impact of dual active ingredient insecticide-treated nets on malaria burden in five regions in sub-Saharan Africa. Malar J 2022; 21:19. [PMID: 35012559 PMCID: PMC8744060 DOI: 10.1186/s12936-021-04026-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Accepted: 12/16/2021] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Vector control tools have contributed significantly to a reduction in malaria burden since 2000, primarily through insecticidal-treated bed nets (ITNs) and indoor residual spraying. In the face of increasing insecticide resistance in key malaria vector species, global progress in malaria control has stalled. Innovative tools, such as dual active ingredient (dual-AI) ITNs that are effective at killing insecticide-resistant mosquitoes have recently been introduced. However, large-scale uptake has been slow for several reasons, including higher costs and limited evidence on their incremental effectiveness and cost-effectiveness. The present report describes the design of several observational studies aimed to determine the effectiveness and cost-effectiveness of dual-AI ITNs, compared to standard pyrethroid-only ITNs, at reducing malaria transmission across a variety of transmission settings. METHODS Observational pilot studies are ongoing in Burkina Faso, Mozambique, Nigeria, and Rwanda, leveraging dual-AI ITN rollouts nested within the 2019 and 2020 mass distribution campaigns in each country. Enhanced surveillance occurring in select study districts include annual cross-sectional surveys during peak transmission seasons, monthly entomological surveillance, passive case detection using routine health facility surveillance systems, and studies on human behaviour and ITN use patterns. Data will compare changes in malaria transmission and disease burden in districts receiving dual-AI ITNs to similar districts receiving standard pyrethroid-only ITNs over three years. The costs of net distribution will be calculated using the provider perspective including financial and economic costs, and a cost-effectiveness analysis will assess incremental cost-effectiveness ratios for Interceptor® G2, Royal Guard®, and piperonyl butoxide ITNs in comparison to standard pyrethroid-only ITNs, based on incidence rate ratios calculated from routine data. CONCLUSIONS Evidence of the effectiveness and cost-effectiveness of the dual-AI ITNs from these pilot studies will complement evidence from two contemporary cluster randomized control trials, one in Benin and one in Tanzania, to provide key information to malaria control programmes, policymakers, and donors to help guide decision-making and planning for local malaria control and elimination strategies. Understanding the breadth of contexts where these dual-AI ITNs are most effective and collecting robust information on factors influencing comparative effectiveness could improve uptake and availability and help maximize their impact.
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Affiliation(s)
- Adama Gansané
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Baltazar Candrinho
- National Malaria Control Programme, Ministry of Health, Maputo, Mozambique
| | | | - Perpetua Uhomoibhi
- National Malaria Elimination Programme, Federal Ministry of Health, Abuja, Nigeria
| | - Sagnon NFalé
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Audu Bala Mohammed
- National Malaria Elimination Programme, Federal Ministry of Health, Abuja, Nigeria
| | | | - Antoine Sanou
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - David Kangoye
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Siaka Debe
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Moubassira Kagone
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | | | - Aline Uwimana
- Rwanda Biomedical Centre, Ministry of Health, Kigali, Rwanda
| | | | | | | | | | | | | | | | | | - Okefu Oyale Okoko
- National Malaria Elimination Programme, Federal Ministry of Health, Abuja, Nigeria
| | - Ibrahim Maikore
- National Malaria Elimination Programme, Federal Ministry of Health, Abuja, Nigeria
| | - Emmanuel Obi
- National Malaria Elimination Programme, Federal Ministry of Health, Abuja, Nigeria
| | | | | | | | - Onoja Ali
- Ibolda Health International, Abuja, Nigeria
| | | | - Joshua Yukich
- School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA, USA
| | - Sara Scates
- School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA, USA
| | - Ellie Sherrard-Smith
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Thomas Churcher
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
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Evolution of the Pyrethroids Target-Site Resistance Mechanisms in Senegal: Early Stage of the Vgsc-1014F and Vgsc-1014S Allelic Frequencies Shift. Genes (Basel) 2021; 12:genes12121948. [PMID: 34946897 PMCID: PMC8701854 DOI: 10.3390/genes12121948] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 11/17/2021] [Accepted: 11/30/2021] [Indexed: 11/17/2022] Open
Abstract
The evolution and spread of insecticide resistance mechanisms amongst malaria vectors across the sub-Saharan Africa threaten the effectiveness and sustainability of current insecticide-based vector control interventions. However, a successful insecticide resistance management plan relies strongly on evidence of historical and contemporary mechanisms circulating. This study aims to retrospectively determine the evolution and spread of pyrethroid resistance mechanisms among natural Anopheles gambiae s.l. populations in Senegal. Samples were randomly drawn from an existing mosquito sample, collected in 2013, 2017, and 2018 from 10 sentinel sites monitored by the Senegalese National Malaria Control Programme (NMCP). Molecular species of An. gambiae s.l. and the resistance mutations at the Voltage-gated Sodium Channel 1014 (Vgsc-1014) locus were characterised using PCR-based assays. The genetic diversity of the Vgsc gene was further analyzed by sequencing. The overall species composition revealed the predominance of Anopheles arabiensis (73.08%) followed by An. gambiae s.s. (14.48%), Anopheles coluzzii (10.94%) and Anopheles gambiae-coluzii hybrids (1.48%). Both Vgsc-1014F and Vgsc-1014S mutations were found in all studied populations with a spatial variation of allele frequencies from 3% to 90%; and 7% to 41%, respectively. The two mutations have been detected since 2013 across all the selected health districts, with Vgsc-L1014S frequency increasing over the years while Vgsc-1014F decreasing. At species level, the Vgsc-1014F and Vgsc-1014S alleles were more frequent amongst An. gambiae s.s. (70%) and An. arabiensis (20%). The Vgsc gene was found to be highly diversified with eight different haplotypes shared between Vgsc-1014F and Vgsc-1014S. The observed co-occurrence of Vgsc-1014F and Vgsc-1014S mutations suggest that pyrethroid resistance is becoming a widespread phenomenon amongst malaria vector populations, and the NMCP needs to address this issue to sustain the gain made in controlling malaria.
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40
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Wolie RZ, Koffi AA, Ahoua Alou LP, Sternberg ED, N'Nan-Alla O, Dahounto A, Yapo FHA, Kanh KMH, Camara S, Oumbouke WA, Tia IZ, Nguetta SPA, Thomas MB, NGuessan R. Evaluation of the interaction between insecticide resistance-associated genes and malaria transmission in Anopheles gambiae sensu lato in central Côte d'Ivoire. Parasit Vectors 2021; 14:581. [PMID: 34801086 PMCID: PMC8605510 DOI: 10.1186/s13071-021-05079-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 10/22/2021] [Indexed: 11/10/2022] Open
Abstract
Background There is evidence that the knockdown resistance gene (Kdr) L1014F and acetylcholinesterase-1 gene (Ace-1R) G119S mutations involved in pyrethroid and carbamate resistance in Anopheles gambiae influence malaria transmission in sub-Saharan Africa. This is likely due to changes in the behaviour, life history and vector competence and capacity of An. gambiae. In the present study, performed as part of a two-arm cluster randomized controlled trial evaluating the impact of household screening plus a novel insecticide delivery system (In2Care Eave Tubes), we investigated the distribution of insecticide target site mutations and their association with infection status in wild An. gambiae sensu lato (s.l.) populations. Methods Mosquitoes were captured in 40 villages around Bouaké by human landing catch from May 2017 to April 2019. Randomly selected samples of An. gambiae s.l. that were infected or not infected with Plasmodium sp. were identified to species and then genotyped for Kdr L1014F and Ace-1R G119S mutations using quantitative polymerase chain reaction assays. The frequencies of the two alleles were compared between Anopheles coluzzii and Anopheles gambiae and then between infected and uninfected groups for each species. Results The presence of An. gambiae (49%) and An. coluzzii (51%) was confirmed in Bouaké. Individuals of both species infected with Plasmodium parasites were found. Over the study period, the average frequency of the Kdr L1014F and Ace-1R G119S mutations did not vary significantly between study arms. However, the frequencies of the Kdr L1014F and Ace-1R G119S resistance alleles were significantly higher in An. gambiae than in An. coluzzii [odds ratio (95% confidence interval): 59.64 (30.81–131.63) for Kdr, and 2.79 (2.17–3.60) for Ace-1R]. For both species, there were no significant differences in Kdr L1014F or Ace-1R G119S genotypic and allelic frequency distributions between infected and uninfected specimens (P > 0.05). Conclusions Either alone or in combination, Kdr L1014F and Ace-1R G119S showed no significant association with Plasmodium infection in wild An. gambiae and An. coluzzii, demonstrating the similar competence of these species for Plasmodium transmission in Bouaké. Additional factors including behavioural and environmental ones that influence vector competence in natural populations, and those other than allele measurements (metabolic resistance factors) that contribute to resistance, should be considered when establishing the existence of a link between insecticide resistance and vector competence. Graphical Abstract ![]()
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Affiliation(s)
- Rosine Z Wolie
- Unité de Recherche et de Pédagogie de Génétique, Université Félix Houphouët-Boigny, UFR Biosciences, Abidjan, Côte d'Ivoire. .,Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire. .,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire.
| | - Alphonsine A Koffi
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Ludovic P Ahoua Alou
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Eleanore D Sternberg
- Department of Entomology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Oulo N'Nan-Alla
- Unité de Recherche et de Pédagogie de Génétique, Université Félix Houphouët-Boigny, UFR Biosciences, Abidjan, Côte d'Ivoire
| | - Amal Dahounto
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire
| | - Florent H A Yapo
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire
| | - Kpahe M H Kanh
- Unité de Recherche et de Pédagogie de Génétique, Université Félix Houphouët-Boigny, UFR Biosciences, Abidjan, Côte d'Ivoire
| | - Soromane Camara
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Welbeck A Oumbouke
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Innovative Vector Control Consortium, IVCC, Liverpool, UK
| | - Innocent Z Tia
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire.,Université Alassane Ouattara, Bouaké, Côte d'Ivoire
| | - Simon-Pierre A Nguetta
- Unité de Recherche et de Pédagogie de Génétique, Université Félix Houphouët-Boigny, UFR Biosciences, Abidjan, Côte d'Ivoire
| | - Matthew B Thomas
- Department of Entomology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA
| | - Raphael NGuessan
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire.,Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
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Piameu M, Nwane P, Toussile W, Mavridis K, Wipf NC, Kouadio PF, Mbakop LR, Mandeng S, Ekoko WE, Toto JC, Ngaffo KL, Ngo Etounde PK, Ngantchou AT, Chouaibou M, Müller P, Awono-Ambene P, Vontas J, Etang J. Pyrethroid and Etofenprox Resistance in Anopheles gambiae and Anopheles coluzzii from Vegetable Farms in Yaoundé, Cameroon: Dynamics, Intensity and Molecular Basis. Molecules 2021; 26:5543. [PMID: 34577014 PMCID: PMC8469461 DOI: 10.3390/molecules26185543] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/03/2021] [Accepted: 09/07/2021] [Indexed: 11/16/2022] Open
Abstract
Previous studies have indicated widespread insecticide resistance in malaria vector populations from Cameroon. However, the intensity of this resistance and underlying mechanisms are poorly known. Therefore, we conducted three cross-sectional resistance surveys between April 2018 and October 2019, using the revised World Health Organization protocol, which includes resistance incidences and intensity assessments. Field-collected Anopheles gambiae s.l. populations from Nkolondom, Nkolbisson and Ekié vegetable farms in the city of Yaoundé were tested with deltamethrin, permethrin, alpha-cypermethrin and etofenprox, using 1× insecticide diagnostic concentrations for resistance incidence, then 5× and 10× concentrations for resistance intensity. Subsamples were analyzed for species identification and the detection of resistance-associated molecular markers using TaqMan® qPCR assays. In Nkolbisson, both An. coluzzii (96%) and An. gambiae s.s. (4%) were found together, whereas only An. gambiae s.s. was present in Nkolondom, and only An. coluzzii was present in Ekié. All three populations were resistant to the four insecticides (<75% mortality rates-MR1×), with intensity generally fluctuating over the time between mod-erate (<98%-MR5×; ≥98%-MR10×) and high (76-97%-MR10×). The kdr L995F, L995S, and N1570Y, and the Ace-1 G280S-resistant alleles were found in An. gambiae from Nkolondom, at 73%, 1%, 16% and 13% frequencies, respectively, whereas only the kdr L995F was found in An. gambiae s.s. from Nkolbisson at a 50% frequency. In An. coluzzii from Nkolbisson and Ekié, we detected only the kdr L995F allele at 65% and 60% frequencies, respectively. Furthermore, expression levels of Cyp6m2, Cyp9k1, and Gste2 metabolic genes were highly upregulated (over fivefold) in Nkolondom and Nkolbisson. Pyrethroid and etofenprox-based vector control interventions may be jeopardized in the prospected areas, due to high resistance intensity, with multiple mechanisms in An. gambiae s.s. and An. coluzzii.
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Affiliation(s)
- Michael Piameu
- Laboratoire de Recherche sur le Paludisme, Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé 999108, Cameroon; (M.P.); (P.N.); (W.T.); (L.R.M.); (S.M.); (W.E.E.); (J.C.T.); (P.A.-A.)
- Ecole des Sciences de la Santé, Université Catholique d’Afrique Centrale, P.O. Box 1110, Yaoundé 999108, Cameroon; (P.K.N.E.); (A.T.N.)
| | - Philippe Nwane
- Laboratoire de Recherche sur le Paludisme, Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé 999108, Cameroon; (M.P.); (P.N.); (W.T.); (L.R.M.); (S.M.); (W.E.E.); (J.C.T.); (P.A.-A.)
- Department de Biologie et Physiologie Animales, Faculté des Sciences, Université de Yaoundé I, P.O. Box 812, Yaoundé 999108, Cameroon
- Centre de Recherche sur les Filarioses et Maladies Tropicales (CRFilMT), P.O. Box 5797, Yaoundé 999108, Cameroon
| | - Wilson Toussile
- Laboratoire de Recherche sur le Paludisme, Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé 999108, Cameroon; (M.P.); (P.N.); (W.T.); (L.R.M.); (S.M.); (W.E.E.); (J.C.T.); (P.A.-A.)
- Département de Mathématiques et Sciences Physiques (MPS), Ecole Nationale Supérieure Polytechnique de Yaoundé (ENSPY), Université de Yaoundé 1, P.O. Box 8390, Yaoundé 999108, Cameroon
| | - Konstantinos Mavridis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 70013 Heraklion, Greece; (K.M.); (J.V.)
| | - Nadja Christina Wipf
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland; (N.C.W.); (P.M.)
- University of Basel, Petersplatz 1, 4001 Basel, Switzerland
| | - Paraudie France Kouadio
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, P.O. Box 1303, Abidjan 1303, Cote d’Ivoire; (P.F.K.); (M.C.)
| | - Lili Ranaise Mbakop
- Laboratoire de Recherche sur le Paludisme, Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé 999108, Cameroon; (M.P.); (P.N.); (W.T.); (L.R.M.); (S.M.); (W.E.E.); (J.C.T.); (P.A.-A.)
- Laboratory of Animal Biology and Physiology, Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé 999108, Cameroon
| | - Stanislas Mandeng
- Laboratoire de Recherche sur le Paludisme, Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé 999108, Cameroon; (M.P.); (P.N.); (W.T.); (L.R.M.); (S.M.); (W.E.E.); (J.C.T.); (P.A.-A.)
- Laboratory of Animal Biology and Physiology, Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé 999108, Cameroon
| | - Wolfgang Eyisap Ekoko
- Laboratoire de Recherche sur le Paludisme, Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé 999108, Cameroon; (M.P.); (P.N.); (W.T.); (L.R.M.); (S.M.); (W.E.E.); (J.C.T.); (P.A.-A.)
- Laboratory of Animal Biology and Physiology, University of Douala, P.O. Box 24157, Douala 999108, Cameroon
| | - Jean Claude Toto
- Laboratoire de Recherche sur le Paludisme, Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé 999108, Cameroon; (M.P.); (P.N.); (W.T.); (L.R.M.); (S.M.); (W.E.E.); (J.C.T.); (P.A.-A.)
| | - Kelly Lionelle Ngaffo
- Institut de Recherche en Sciences de la Santé (IRSS), Centre d’excellence Africain en Innovations Biotechnologiques pour l’élimination des Maladies à Transmission Vectorielle (CEA/ITECH-MTV), Université Nazi Boni, P.O. Box 545, Bobo-Dioulasso 22620, Burkina Faso;
| | - Petronile Klorane Ngo Etounde
- Ecole des Sciences de la Santé, Université Catholique d’Afrique Centrale, P.O. Box 1110, Yaoundé 999108, Cameroon; (P.K.N.E.); (A.T.N.)
| | - Arthur Titcho Ngantchou
- Ecole des Sciences de la Santé, Université Catholique d’Afrique Centrale, P.O. Box 1110, Yaoundé 999108, Cameroon; (P.K.N.E.); (A.T.N.)
| | - Mouhamadou Chouaibou
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, P.O. Box 1303, Abidjan 1303, Cote d’Ivoire; (P.F.K.); (M.C.)
| | - Pie Müller
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland; (N.C.W.); (P.M.)
- University of Basel, Petersplatz 1, 4001 Basel, Switzerland
| | - Parfait Awono-Ambene
- Laboratoire de Recherche sur le Paludisme, Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé 999108, Cameroon; (M.P.); (P.N.); (W.T.); (L.R.M.); (S.M.); (W.E.E.); (J.C.T.); (P.A.-A.)
| | - John Vontas
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 70013 Heraklion, Greece; (K.M.); (J.V.)
- Department of Crop Science, Agricultural University of Athens, Iera Odos 875, 11855 Athens, Greece
| | - Josiane Etang
- Laboratoire de Recherche sur le Paludisme, Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé 999108, Cameroon; (M.P.); (P.N.); (W.T.); (L.R.M.); (S.M.); (W.E.E.); (J.C.T.); (P.A.-A.)
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, P.O. Box 2701, Douala 999108, Cameroon
- Institute for Insect Biotechnology, Justus-Liebig-University Gießen, 35394 Gießen, Germany
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Yin J, Yamba F, Zheng C, Zhou S, Smith SJ, Wang L, Li H, Xia Z, Xiao N. Molecular Detection of Insecticide Resistance Mutations in Anopheles gambiae from Sierra Leone Using Multiplex SNaPshot and Sequencing. Front Cell Infect Microbiol 2021; 11:666469. [PMID: 34490134 PMCID: PMC8416995 DOI: 10.3389/fcimb.2021.666469] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 08/05/2021] [Indexed: 11/22/2022] Open
Abstract
Vector control interventions including long-lasting insecticidal nets and indoor residual spraying are important for malaria control and elimination. And effectiveness of these interventions depends entirely on the high level of susceptibility of malaria vectors to insecticides. However, the insecticide resistance in majority of mosquito vector species across African countries is a serious threat to the success of vector control efforts with the extensive use of insecticides, while no data on insecticide resistance was reported from Sierra Leone in the past decade. In the present study, the polymerase chain reaction was applied for the identification of species of 757 dry adult female Anopheles gambiae mosquitoes reared from larvae collected from four districts in Sierra Leone during May and June 2018. And the mutations of kdr, rdl, ace-1 genes in An. gambiae were detected using SNaPshot and sequencing. As a result, one sample from Western Area Rural district belonged to Anopheles melas, and 748 An. gambiae were identified. Furthermore, the rdl mutations, kdr west mutations and ace-1 mutation were found. The overall frequency was 35.7%, 0.3%, 97.6% and 4.5% in A296G rdl, A296S rdl, kdrW and ace-1, respectively. The frequencies of A296G rdl mutation (P < 0.001), kdrW mutation (P = 0.001) and ace-1 mutation (P < 0.001) were unevenly distributed in four districts, respectively, while no statistical significance was found in A296S rdl mutation (P = 0.868). In addition, multiple resistance patterns were also found. In conclusion, multiple mutations involved in insecticide resistance in An. gambiae populations in Sierra Leone were detected in the kdrW, A296G rdl and ace-1 alleles in the present study. It is necessary to monitor vector susceptibility levels to insecticides used in this country, and update the insecticide resistance monitoring and management strategy.
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Affiliation(s)
- Jianhai Yin
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, China
| | - Frederick Yamba
- National Malaria Control Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Canjun Zheng
- Division of Infectious Diseases, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Shuisen Zhou
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, China
| | - Samuel Juana Smith
- National Malaria Control Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Lili Wang
- Center for Global Public Health, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Hongmei Li
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, China
| | - Zhigui Xia
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, China
| | - Ning Xiao
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, China
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43
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Antonio-Nkondjio C, Doumbe-Belisse P, Djamouko-Djonkam L, Ngadjeu CS, Talipouo A, Kopya E, Bamou R, Mayi MPA, Sonhafouo-Chiana N, Nkahe DL, Tabue R, Fosah DA, Bigoga JD, Awono-Ambene P, Wondji CS. High efficacy of microbial larvicides for malaria vectors control in the city of Yaounde Cameroon following a cluster randomized trial. Sci Rep 2021; 11:17101. [PMID: 34429446 PMCID: PMC8385066 DOI: 10.1038/s41598-021-96362-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 08/03/2021] [Indexed: 11/12/2022] Open
Abstract
The rapid expansion of insecticide resistance and outdoor malaria transmission are affecting the efficacy of current malaria control measures. In urban settings, where malaria transmission is focal and breeding habitats are few, fixed and findable, the addition of anti-larval control measures could be efficient for malaria vector control. But field evidences for this approach remains scarce. Here we provide findings of a randomized-control larviciding trial conducted in the city of Yaoundé that support the efficacy of this approach. A two arms random control trial design including 26 clusters of 2 to 4 km2 each (13 clusters in the intervention area and 13 in the non-intervention area) was used to assess larviciding efficacy. The microbial larvicide VectoMax combining Bacillus thuringiensis var israelensis (Bti) and Bacillus sphaericus in a single granule was applied every 2 weeks in all standing water collection points. The anopheline density collected using CDC light traps was used as the primary outcome, secondary outcomes included the entomological inoculation rate, breeding habitats with anopheline larvae, and larval density. Baseline entomological data collection was conducted for 17 months from March 2017 to July 2018 and the intervention lasted 26 months from September 2018 to November 2020. The intervention was associated with a reduction of 68% of adult anopheline biting density and of 79% of the entomological inoculation rate (OR 0.21; 95% CI 0.14-0.30, P < 0.0001). A reduction of 68.27% was recorded for indoor biting anophelines and 57.74% for outdoor biting anophelines. No impact on the composition of anopheline species was recorded. A reduction of over 35% of adult Culex biting densities was recorded. The study indicated high efficacy of larviciding for reducing malaria transmission intensity in the city of Yaoundé. Larviciding could be part of an integrated control approach for controlling malaria vectors and other mosquito species in the urban environment.
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Affiliation(s)
- Christophe Antonio-Nkondjio
- Laboratoire de Recherche Sur Le Paludisme, Organisation de Coordination Pour La Lutte Contre Les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun.
- Department of Vector Biology, Liverpool School of Tropical Medicine Pembroke Place, Liverpool, L3 5QA, UK.
| | - P Doumbe-Belisse
- Laboratoire de Recherche Sur Le Paludisme, Organisation de Coordination Pour La Lutte Contre Les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun
- Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - L Djamouko-Djonkam
- Laboratoire de Recherche Sur Le Paludisme, Organisation de Coordination Pour La Lutte Contre Les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun
- Vector Borne Diseases Laboratory of the Biology and Applied Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang, Cameroon
| | - C S Ngadjeu
- Laboratoire de Recherche Sur Le Paludisme, Organisation de Coordination Pour La Lutte Contre Les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun
- Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - A Talipouo
- Laboratoire de Recherche Sur Le Paludisme, Organisation de Coordination Pour La Lutte Contre Les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun
- Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - E Kopya
- Laboratoire de Recherche Sur Le Paludisme, Organisation de Coordination Pour La Lutte Contre Les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun
- Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - R Bamou
- Laboratoire de Recherche Sur Le Paludisme, Organisation de Coordination Pour La Lutte Contre Les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun
- Vector Borne Diseases Laboratory of the Biology and Applied Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang, Cameroon
| | - M P Audrey Mayi
- Vector Borne Diseases Laboratory of the Biology and Applied Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang, Cameroon
| | - N Sonhafouo-Chiana
- Laboratoire de Recherche Sur Le Paludisme, Organisation de Coordination Pour La Lutte Contre Les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun
- Faculty of Sciences, University of Buea, P.O. Box 63, Buea, Cameroon
| | - D L Nkahe
- Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - R Tabue
- Ministry of Public Health, National Malaria Control Programme, Yaoundé, Cameroon
| | - D Achu Fosah
- Ministry of Public Health, National Malaria Control Programme, Yaoundé, Cameroon
| | - Jude D Bigoga
- Laboratory for Vector Biology and Control, National Reference Unit for Vector Control, The Biotechnology Center, Nkolbisson-University of Yaounde I, P.O. Box 3851, Messa, Yaoundé, Cameroon
- Department of Biochemistry, Faculty of Science, University of Yaounde I, Yaoundé, Cameroon
| | - P Awono-Ambene
- Laboratoire de Recherche Sur Le Paludisme, Organisation de Coordination Pour La Lutte Contre Les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroun
| | - Charles S Wondji
- Department of Vector Biology, Liverpool School of Tropical Medicine Pembroke Place, Liverpool, L3 5QA, UK
- Centre for Research in Infectious Diseases, Yaoundé, Cameroon
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Longo-Pendy NM, Tene-Fossog B, Tawedi RE, Akone-Ella O, Toty C, Rahola N, Braun JJ, Berthet N, Kengne P, Costantini C, Ayala D. Ecological plasticity to ions concentration determines genetic response and dominance of Anopheles coluzzii larvae in urban coastal habitats of Central Africa. Sci Rep 2021; 11:15781. [PMID: 34349141 PMCID: PMC8338965 DOI: 10.1038/s41598-021-94258-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 06/29/2021] [Indexed: 02/07/2023] Open
Abstract
In Central Africa, the malaria vector Anopheles coluzzii is predominant in urban and coastal habitats. However, little is known about the environmental factors that may be involved in this process. Here, we performed an analysis of 28 physicochemical characteristics of 59 breeding sites across 5 urban and rural sites in coastal areas of Central Africa. We then modelled the relative frequency of An. coluzzii larvae to these physicochemical parameters in order to investigate environmental patterns. Then, we assessed the expression variation of 10 candidate genes in An. coluzzii, previously incriminated with insecticide resistance and osmoregulation in urban settings. Our results confirmed the ecological plasticity of An. coluzzii larvae to breed in a large range of aquatic conditions and its predominance in breeding sites rich in ions. Gene expression patterns were comparable between urban and rural habitats, suggesting a broad response to ions concentrations of whatever origin. Altogether, An. coluzzii exhibits a plastic response to occupy both coastal and urban habitats. This entails important consequences for malaria control in the context of the rapid urban expansion in Africa in the coming years.
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Affiliation(s)
| | | | - Robert E. Tawedi
- grid.473396.cInstitut de Recherches Géologiques Et Minières / Centre de Recherches Hydrologiques, Yaoundé, Cameroon
| | | | - Celine Toty
- grid.462603.50000 0004 0382 3424MIVEGEC, Univ Montpellier, CNRS, IRD, 911 avenue Agropolis, BP 64501, 34394 Montpellier, France
| | - Nil Rahola
- grid.462603.50000 0004 0382 3424MIVEGEC, Univ Montpellier, CNRS, IRD, 911 avenue Agropolis, BP 64501, 34394 Montpellier, France
| | - Jean-Jacques Braun
- grid.473396.cInstitut de Recherches Géologiques Et Minières / Centre de Recherches Hydrologiques, Yaoundé, Cameroon ,grid.462928.30000 0000 9033 1612Géosciences Environnement Toulouse, Université de Toulouse, CNRS, IRD, Toulouse, France ,International Joint Laboratory DYCOFAC, IRGM-UY1-IRD, BP 1857, Yaoundé, Cameroon
| | - Nicolas Berthet
- grid.418115.80000 0004 1808 058XCIRMF, Franceville, Gabon ,grid.428999.70000 0001 2353 6535Institut Pasteur, Unité Environnement Et Risque Infectieux, Cellule D’Intervention Biologique D’Urgence, Paris, France
| | - Pierre Kengne
- grid.418115.80000 0004 1808 058XCIRMF, Franceville, Gabon ,grid.462603.50000 0004 0382 3424MIVEGEC, Univ Montpellier, CNRS, IRD, 911 avenue Agropolis, BP 64501, 34394 Montpellier, France
| | - Carlo Costantini
- grid.462603.50000 0004 0382 3424MIVEGEC, Univ Montpellier, CNRS, IRD, 911 avenue Agropolis, BP 64501, 34394 Montpellier, France
| | - Diego Ayala
- grid.418115.80000 0004 1808 058XCIRMF, Franceville, Gabon ,grid.462603.50000 0004 0382 3424MIVEGEC, Univ Montpellier, CNRS, IRD, 911 avenue Agropolis, BP 64501, 34394 Montpellier, France
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Zhang H, Li M, Tan R, Deng C, Huang B, Wu Z, Zheng S, Guo W, Tuo F, Yuan Y, Bandeira CA, Rompão DH, Xu Q, Song J, Wang Q. Presence of L1014F Knockdown-Resistance Mutation in Anopheles gambiae s.s. From São Tomé and Príncipe. Front Cell Infect Microbiol 2021; 11:633905. [PMID: 34307185 PMCID: PMC8295031 DOI: 10.3389/fcimb.2021.633905] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 06/08/2021] [Indexed: 11/18/2022] Open
Abstract
Malaria, one of the most serious parasitic diseases, kills thousands of people every year, especially in Africa. São Tomé and Príncipe are known to have stable transmission of malaria. Indoor residual spraying (IRS) of insecticides and long-lasting insecticidal nets (LLIN) are considered as an effective malaria control interventions in these places. The resistance status of Anopheles gambiae s.s. from Agua Grande, Caue, and Lemba of São Tomé and Príncipe to insecticides, such as dichlorodiphenyltrichloroethane (DDT) (4.0%), deltamethrin (0.05%), permethrin (0.75%), fenitrothion (1.0%), and malathion (5.0%), were tested according to the WHO standard protocol. DNA extraction, species identification, as well as kdr and ace-1R genotyping were done with the surviving and dead mosquitoes post testing. They showed resistance to cypermethrin with mortality rates ranging from 89.06% to 89.66%. Mosquitoes collected from Agua Grande, Caue, and Lemba displayed resistance to DDT and fenitrothion with mortality rates higher than 90%. No other species were detected in these study localities other than Anopheles gambiae s.s. The frequency of L1014F was high in the three investigated sites, which was detected for the first time in São Tomé and Príncipe. No ace-1R mutation was detected in all investigated sites. The high frequency of L1014F showed that kdr L1014F mutation might be related to insecticide resistance to Anopheles gambiae s.s. populations from São Tomé and Príncipe. Insecticide resistance status is alarming and, therefore, future malaria vector management should be seriously considered by the government of São Tomé and Príncipe.
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Affiliation(s)
- Hongying Zhang
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China.,Science and Technology Institute, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Mingqiang Li
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Ruixiang Tan
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Changsheng Deng
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China.,The Ministry of Health, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Bo Huang
- Science and Technology Institute, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Zhibin Wu
- The Ministry of Health, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Shaoqing Zheng
- Science and Technology Institute, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Wenfeng Guo
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China.,The Ministry of Health, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Fei Tuo
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Yueming Yuan
- Science and Technology Institute, Guangzhou University of Chinese Medicine, Guangzhou, China
| | | | | | - Qin Xu
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China.,The Ministry of Health, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jianping Song
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China.,The Ministry of Health, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Qi Wang
- Artemisinin Research Center, Guangzhou University of Chinese Medicine, Guangzhou, China.,The Ministry of Health, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
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Millán-Leiva A, Marín Ó, Christmon K, vanEngelsdorp D, González-Cabrera J. Mutations associated with pyrethroid resistance in Varroa mite, a parasite of honey bees, are widespread across the United States. PEST MANAGEMENT SCIENCE 2021; 77:3241-3249. [PMID: 33728766 DOI: 10.1002/ps.6366] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 02/11/2021] [Accepted: 03/17/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Managed honey bees are key pollinators of many crops and play an essential role in the United States food production. For more than ten years, beekeepers in the United States have been reporting high rates of colony losses. One of the drivers of these losses is the parasitic mite Varroa destructor. Maintaining healthy honey bee colonies in the United States is dependent on a successful control of this mite. The pyrethroid tau-fluvalinate (Apistan®) was among the first synthetic varroacides registered in the United States. With over 20 years of use, mites resistant to Apistan® have emerged, and so it is unsurprising that treatment failures have been reported. Resistance to tau-fluvalinate in US mite populations is associated with point mutations at position 925 of the voltage-gated sodium channel. RESULTS Here, we have generated a distribution map of pyrethroid resistance alleles in Varroa samples collected from US apiaries in 2016 and 2017, using a high throughput allelic discrimination assay based on TaqMan®. Our results evidence that knockdown resistance (kdr)-type mutations are widely distributed in Varroa populations across the country showing high variability among apiaries. We used these data to predict the phenotype of the mites in the case of treatments with pyrethroids. CONCLUSION We highlight the relevance of monitoring the resistance in mite populations to achieve an efficient control of this pest. We also put forward the benefits of implementing this methodology to provide data for designing pest management programs aiming to control Varroa. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Anabel Millán-Leiva
- Department of Genetics, Institute BIOTECMED, Universitat de València, Burjassot, Spain
| | - Óscar Marín
- Department of Genetics, Institute BIOTECMED, Universitat de València, Burjassot, Spain
| | | | | | - Joel González-Cabrera
- Department of Genetics, Institute BIOTECMED, Universitat de València, Burjassot, Spain
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An increasing role of pyrethroid-resistant Anopheles funestus in malaria transmission in the Lake Zone, Tanzania. Sci Rep 2021; 11:13457. [PMID: 34188090 PMCID: PMC8241841 DOI: 10.1038/s41598-021-92741-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 06/08/2021] [Indexed: 02/06/2023] Open
Abstract
Anopheles funestus is playing an increasing role in malaria transmission in parts of sub-Saharan Africa, where An. gambiae s.s. has been effectively controlled by long-lasting insecticidal nets. We investigated vector population bionomics, insecticide resistance and malaria transmission dynamics in 86 study clusters in North-West Tanzania. An. funestus s.l. represented 94.5% (4740/5016) of all vectors and was responsible for the majority of malaria transmission (96.5%), with a sporozoite rate of 3.4% and average monthly entomological inoculation rate (EIR) of 4.57 per house. Micro-geographical heterogeneity in species composition, abundance and transmission was observed across the study district in relation to key ecological differences between northern and southern clusters, with significantly higher densities, proportions and EIR of An. funestus s.l. collected from the South. An. gambiae s.l. (5.5%) density, principally An. arabiensis (81.1%) and An. gambiae s.s. (18.9%), was much lower and closely correlated with seasonal rainfall. Both An. funestus s.l. and An. gambiae s.l. were similarly resistant to alpha-cypermethrin and permethrin. Overexpression of CYP9K1, CYP6P3, CYP6P4 and CYP6M2 and high L1014S-kdr mutation frequency were detected in An. gambiae s.s. populations. Study findings highlight the urgent need for novel vector control tools to tackle persistent malaria transmission in the Lake Region of Tanzania.
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Orondo PW, Nyanjom SG, Atieli H, Githure J, Ondeto BM, Ochwedo KO, Omondi CJ, Kazura JW, Lee MC, Zhou G, Zhong D, Githeko AK, Yan G. Insecticide resistance status of Anopheles arabiensis in irrigated and non-irrigated areas in western Kenya. Parasit Vectors 2021; 14:335. [PMID: 34174946 PMCID: PMC8235622 DOI: 10.1186/s13071-021-04833-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 06/09/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria control in Kenya is based on case management and vector control using long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). However, the development of insecticide resistance compromises the effectiveness of insecticide-based vector control programs. The use of pesticides for agricultural purposes has been implicated as one of the sources driving the selection of resistance. The current study was undertaken to assess the status and mechanism of insecticide resistance in malaria vectors in irrigated and non-irrigated areas with varying agrochemical use in western Kenya. METHODS The study was carried out in 2018-2019 in Homa Bay County, western Kenya. The bioassay was performed on adults reared from larvae collected from irrigated and non-irrigated fields in order to assess the susceptibility of malaria vectors to different classes of insecticides following the standard WHO guidelines. Characterization of knockdown resistance (kdr) and acetylcholinesterase-inhibiting enzyme/angiotensin-converting enzyme (Ace-1) mutations within Anopheles gambiae s.l. species was performed using the polymerase chain reaction (PCR) method. To determine the agricultural and public health insecticide usage pattern, a questionnaire was administered to farmers, households, and veterinary officers in the study area. RESULTS Anopheles arabiensis was the predominant species in the irrigated (100%, n = 154) area and the dominant species in the non-irrigated areas (97.5%, n = 162), the rest being An. gambiae sensu stricto. In 2018, Anopheles arabiensis in the irrigated region were susceptible to all insecticides tested, while in the non-irrigated region reduced mortality was observed (84%) against deltamethrin. In 2019, phenotypic mortality was decreased (97.8-84% to 83.3-78.2%). In contrast, high mortality from malathion (100%), DDT (98.98%), and piperonyl butoxide (PBO)-deltamethrin (100%) was observed. Molecular analysis of the vectors from the irrigated and non-irrigated areas revealed low levels of leucine-serine/phenylalanine substitution at position 1014 (L1014S/L1014F), with mutation frequencies of 1-16%, and low-frequency mutation in the Ace-1R gene (0.7%). In addition to very high coverage of LLINs impregnated with pyrethroids and IRS with organophosphate insecticides, pyrethroids were the predominant chemical class of pesticides used for crop and animal protection. CONCLUSION Anopheles arabiensis from irrigated areas showed increased phenotypic resistance, and the intensive use of pesticides for crop protection in this region may have contributed to the selection of resistance genes observed. The susceptibility of these malaria vectors to organophosphates and PBO synergists in pyrethroids offers a promising future for IRS and insecticide-treated net-based vector control interventions. These findings emphasize the need for integrated vector control strategies, with particular attention to agricultural practices to mitigate mosquito resistance to insecticides.
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Affiliation(s)
- Pauline Winnie Orondo
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya. .,International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya.
| | - Steven G Nyanjom
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
| | - Harrysone Atieli
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya.,School of Public Health and Community Development, Maseno University, Kisumu, Kenya
| | - John Githure
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - Benyl M Ondeto
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - Kevin O Ochwedo
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - Collince J Omondi
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - James W Kazura
- Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Ming-Chieh Lee
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Guofa Zhou
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Daibin Zhong
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Andrew K Githeko
- International Center of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya. .,Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya.
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA.
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Hamid-Adiamoh M, Nwakanma D, Assogba BS, Ndiath MO, D’Alessandro U, Afrane YA, Amambua-Ngwa A. Influence of insecticide resistance on the biting and resting preferences of malaria vectors in the Gambia. PLoS One 2021; 16:e0241023. [PMID: 34166376 PMCID: PMC8224845 DOI: 10.1371/journal.pone.0241023] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 06/11/2021] [Indexed: 11/23/2022] Open
Abstract
Background The scale-up of indoor residual spraying and long-lasting insecticidal nets, together with other interventions have considerably reduced the malaria burden in The Gambia. This study examined the biting and resting preferences of the local insecticide-resistant vector populations few years following scale-up of anti-vector interventions. Method Indoor and outdoor-resting Anopheles gambiae mosquitoes were collected between July and October 2019 from ten villages in five regions in The Gambia using pyrethrum spray collection (indoor) and prokopack aspirator from pit traps (outdoor). Polymerase chain reaction assays were performed to identify molecular species, insecticide resistance mutations, Plasmodium infection rate and host blood meal. Results A total of 844 mosquitoes were collected both indoors (421, 49.9%) and outdoors (423, 50.1%). Four main vector species were identified, including An. arabiensis (indoor: 15%, outdoor: 26%); An. coluzzii (indoor: 19%, outdoor: 6%), An. gambiae s.s. (indoor: 11%, outdoor: 16%), An. melas (indoor: 2%, outdoor: 0.1%) and hybrids of An. coluzzii-An. gambiae s.s (indoors: 3%, outdoors: 2%). A significant preference for outdoor resting was observed in An. arabiensis (Pearson X2 = 22.7, df = 4, P<0.001) and for indoor resting in An. coluzzii (Pearson X2 = 55.0, df = 4, P<0.001). Prevalence of the voltage-gated sodium channel (Vgsc)-1014S was significantly higher in the indoor-resting (allele freq. = 0.96, 95%CI: 0.78–1, P = 0.03) than outdoor-resting (allele freq. = 0.82, 95%CI: 0.76–0.87) An. arabiensis population. For An. coluzzii, the prevalence of most mutation markers was higher in the outdoor (allele freq. = 0.92, 95%CI: 0.81–0.98) than indoor-resting (allele freq. = 0.78, 95%CI: 0.56–0.86) mosquitoes. However, in An. gambiae s.s., the prevalence of Vgsc-1014F, Vgsc-1575Y and GSTe2-114T was high (allele freq. = 0.96–1), but did not vary by resting location. The overall sporozoite positivity rate was 1.3% (95% CI: 0.5–2%) in mosquito populations. Indoor-resting An. coluzzii had mainly fed on human blood while indoor-resting An. arabiensis fed on animal blood. Conclusion In this study, high levels of resistance mutations were observed that could be influencing the mosquito populations to rest indoors or outdoors. The prevalent animal-biting behaviour demonstrated in the mosquito populations suggest that larval source management could be an intervention to complement vector control in this setting.
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Affiliation(s)
- Majidah Hamid-Adiamoh
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP) and Department of Biochemistry, Cell and Molecular, University of Ghana, Legon, Accra, Ghana
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
- * E-mail:
| | - Davis Nwakanma
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Benoit Sessinou Assogba
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Mamadou Ousmane Ndiath
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Umberto D’Alessandro
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Yaw A. Afrane
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP) and Department of Biochemistry, Cell and Molecular, University of Ghana, Legon, Accra, Ghana
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Accra, Ghana
| | - Alfred Amambua-Ngwa
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
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50
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Zhao N, Sesay I, Tu H, Yamba F, Lu L, Guo Y, Song X, Wang J, Liu X, Yue Y, Wu H, Liu Q. Entomological and Molecular Surveillance of Anopheles Mosquitoes in Freetown, Sierra Leone, 2019. Front Public Health 2021; 9:649672. [PMID: 34222167 PMCID: PMC8247763 DOI: 10.3389/fpubh.2021.649672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 05/26/2021] [Indexed: 11/23/2022] Open
Abstract
Background: Malaria is endemic in Sierra Leone, with stable and perennial transmission in all parts of the country. At present, the main prevention and control measures for mosquito vectors here involve insecticide treated nets (ITN) and indoor residual spraying (IRS). The most recent entomological surveillance was conducted prior to the civil war, between 1990 and 1994. Therefore, a new entomological surveillance required to support targeted malaria control strategies. Methods:Anopheles mosquitoes were collected between June and December 2019 using the light trap method. On these, we conducted species identification, analyzed seasonal fluctuation and Plasmodium infection rate, and monitored insecticide resistance. Results: Surveillance of seasonal fluctuation showed that there were two peak of Anopheles density in July (mean 13.67 mosquitoes/trap/night) and October (mean 13.00 mosquitoes/trap/night). Meanwhile, the lowest Anopheles density was seen in early September. Ninety-one representatives of Anopheles gambiae s.l. were selected and identified as An. coluzzii (n = 35) and An. gambiae s.s. (n = 56) using PCR. An. coluzzii and An. gambiae s.s. were found to be heterozygous resistant to the knockdown resistance (kdr) L1014F mutation (100%). Meanwhile, the East African mutation (kdr L1014S) was absent in the tested mosquitoes. Three mosquitoes that tested positive for the parasite, had an individual Plasmodium falciparum infection rate of 12.50, 16.67, and 14.29%. The sampling dates of positive mosquitoes were distributed in the two periods of peak Anopheles mosquito density. Conclusion: This study identified the dominant Anopheles species in Freetown as An. gambiae while the predominant species within the An. gambiae complex was An. gambiae sensu stricto. Surveillance of seasonal fluctuations and high P. falciparum infection rates in Anopheles indicate that the alternation of drought and rainy seasons from June to July, and from October to November, are the key periods for malaria control and prevention in Freetown, Sierra Leone. The high frequency of kdr allele mutations in An. gambiae calls for close monitoring of vector susceptibility to insecticides and tracing of resistance mechanisms in order to develop more effective vector control measures and strategies.
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Affiliation(s)
- Ning Zhao
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China.,Sierra Leone-China Friendship Biosafety Laboratory, Freetown, Sierra Leone
| | - Ishaq Sesay
- Sierra Leone-China Friendship Biosafety Laboratory, Freetown, Sierra Leone
| | - Hong Tu
- Sierra Leone-China Friendship Biosafety Laboratory, Freetown, Sierra Leone.,Chinese Center for Disease Control and Prevention, National Institute of Parasitic Diseases, Shanghai, China
| | - Frederick Yamba
- Ministry of Health and Sanitation of Sierra Leone, Freetown, Sierra Leone
| | - Liang Lu
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China.,Sierra Leone-China Friendship Biosafety Laboratory, Freetown, Sierra Leone
| | - Yuhong Guo
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Xiuping Song
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Jun Wang
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Xiaobo Liu
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Yujuan Yue
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Haixia Wu
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
| | - Qiyong Liu
- State Key Laboratory of Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, National Institute for Communicable Disease Control and Prevention, Beijing, China
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