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Govoetchan R, Fongnikin A, Hueha C, Ahoga J, Boko C, Syme T, Issiakou R, Agbevo A, Aikpon R, Small G, Snetselaar J, Ossè R, Tokponnon F, Padonou GG, Ngufor C. Malaria prevalence and transmission in the Zakpota sub-district of central Benin: baseline characteristics for a community randomised trial of a new insecticide for indoor residual spraying. Parasit Vectors 2024; 17:303. [PMID: 38997729 PMCID: PMC11245802 DOI: 10.1186/s13071-024-06342-1] [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: 02/08/2024] [Accepted: 06/01/2024] [Indexed: 07/14/2024] Open
Abstract
BACKGROUND Malaria transmission is known to be perennial and heterogeneous in Benin. Studies assessing local malaria prevalence, transmission levels and vector characteristics are critical for designing, monitoring and evaluating new vector control interventions in community trials. We conducted a study in the Zakpota sub-district of central Benin to collect baseline data on household characteristics, malaria prevalence, vector characteristics and transmission dynamics in preparation for a randomised controlled trial to evaluate the community impact of VECTRON™ T500, a new broflanilide indoor residual spraying (IRS) product. METHODS A total of 480 children under 5 years of age from the 15 villages of the sub-district were tested for malaria by rapid diagnostic tests (RDTs). Mosquitoes were collected by human landing catches (HLCs), pyrethrum spray catches (PSCs) and Centers for Disease Control and Prevention miniature light traps (CDC-LTs) in selected houses in each village to assess vector density, composition, vector infectivity and prevalence of insecticide resistance markers. Bioassays were performed to detect vector susceptibility to pyrethroids, broflanilide (6 µg/bottle) and clothianidin (90 µg/bottle). RESULTS A total of 9080 households were enumerated in the 15 study villages. Insecticide-treated net (ITN) usage was > 90%, with 1-2 ITNs owned per household. Houses were constructed mainly with cement (44%) and mud (38%) substrates or a mixture of cement and mud (18%), and 60% of them had open eaves. The overall prevalence of P. falciparum infection was 19% among surveyed children: 20% among females and 18% among males. The haemoglobin rate showed an anaemia (< 11 g/dl) prevalence of 66%. Anopheles coluzzii and An. gambiae sensu stricto (s.s.) were the two vector species present at an overall proportion of 46% versus 54%, respectively. The human biting rate was 2.3 bites per person per night (b/p/n) and biting occurred mostly indoors compared with outdoors (IRR = 0.776; P = 0.001). The overall proportion of outdoor biting was 44% and exceeded indoor biting in three villages. The sporozoite rate was 2% with a combined yearly entomological inoculation rate (EIR) of 16.1 infected bites per person per year (ib/p/y). There was great variability in malaria transmission risk across the villages, with EIR ranging from 0 to 29.3 ib/p/y. The vector population showed a high intensity of resistance to pyrethroids across the study villages but was largely susceptible to broflanilide and clothianidin. CONCLUSIONS This study found high levels of malaria prevalence, vector density and transmission in the Zakpota sub-district despite the wide use of insecticide-treated nets. The vector population was mostly indoor resting and showed a high intensity of pyrethroid resistance but was generally fully susceptible to broflanilide. These findings demonstrated the suitability of the study area for the assessment of VECTRON™ T500 in a community randomised trial.
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Affiliation(s)
- Renaud Govoetchan
- London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK.
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.
- Pan-African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin.
| | - Augustin Fongnikin
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Pan-African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Corneille Hueha
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Pan-African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Juniace Ahoga
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Pan-African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Chantal Boko
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | - Thomas Syme
- London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Pan-African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Riliwanou Issiakou
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Pan-African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Abel Agbevo
- London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Pan-African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Rock Aikpon
- National Malaria Control Programme, Ministry of Health, Cotonou, Benin
| | - Graham Small
- Innovative Vector Control Consortium (IVCC), Liverpool, UK
| | | | - Razaki Ossè
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | | | | | - Corine Ngufor
- London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK.
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.
- Pan-African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin.
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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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Yovogan B, Sovi A, Djènontin A, Adoha CJ, Akinro B, Accrombessi M, Dangbénon E, Koukpo CZ, Affolabi ZK, Agboho PA, Kpanou CD, Assongba L, Missihoun AA, Tokponnon TF, Agbangla C, Padonou GG, Messenger LA, Ngufor C, Cook J, Akogbéto MC, Protopopoff N. The impact of pyrethroid-pyriproxyfen and pyrethroid-chlorfenapyr long-lasting insecticidal nets on density of primary malaria vectors Anopheles gambiae s.s. and Anopheles coluzzii in Benin: a secondary analysis of a cluster randomised controlled trial. Parasit Vectors 2024; 17:7. [PMID: 38178161 PMCID: PMC10768265 DOI: 10.1186/s13071-023-06104-5] [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: 10/06/2023] [Accepted: 12/17/2023] [Indexed: 01/06/2024] Open
Abstract
BACKGROUND Long-lasting insecticidal nets (LLINs) may have different impacts on distinct mosquito vector species. We assessed the efficacy of pyrethroid-pyriproxyfen and pyrethroid-chlorfenapyr LLINs on the density of Anopheles gambiae s.s. and An. coluzzii compared to pyrethroid-only nets in a three-arm cluster randomised control trial in Benin. METHODS Indoor and outdoor collections of adult mosquitoes took place in 60 clusters using human landing catches at baseline and every 3 months for 2 years. After morphological identification, around 15% of randomly selected samples of An. gambiae s.l. were dissected to determine parity, species (using PCR). RESULTS Overall, a total of 46,613 mosquito specimens were collected at baseline and 259,250 in the eight quarterly collections post-net distribution. Post-net distribution, approximately 70% of the specimens of An. gambiae s.l. speciated were An. coluzzii, while the rest were mostly composed of An. gambiae s.s. with a small proportion (< 1%) of hybrids (An. gambiae/coluzzii). There was no evidence of a significant reduction in vector density indoors in either primary vector species [An. coluzzii: DR (density ratio) = 0.62 (95% CI 0.21-1.77), p = 0.3683 for the pyrethroid-pyriproxyfen LLIN and DR = 0.56 (95% CI 0.19-1.62), p = 0.2866 for the pyrethroid-chlorfenapyr LLIN, An. gambiae s.s.: DR = 0.52 (95% CI 0.18-1.46), p = 0.2192 for the pyrethroid-pyriproxyfen LLIN and DR = 0.53 (95% CI 0.19-1.46), p = 0.2222 for the pyrethroid-chlorfenapyr]. The same trend was observed outdoors. Parity rates of An. gambiae s.l. were also similar across study arms. CONCLUSIONS Compared with pyrethroid-only LLINs, pyrethroid-chlorfenapyr LLINs and pyrethroid-pyriproxyfen LLINs performed similarly against the two primary mosquito species An. gambiae s.s. and An. coluzzii in Benin.
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Affiliation(s)
- Boulais Yovogan
- Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey-Calavi, Benin.
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin.
| | - Arthur Sovi
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin.
- Faculté d'Agronomie, Université de Parakou, Parakou, Benin.
- Faculty of Infectious and Tropical Diseases, Department of Disease Control, The London School of Hygiene and Tropical Medicine, London, UK.
| | - Armel Djènontin
- Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey-Calavi, Benin
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Constantin J Adoha
- Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey-Calavi, Benin
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Bruno Akinro
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Manfred Accrombessi
- Faculty of Infectious and Tropical Diseases, Department of Disease Control, The London School of Hygiene and Tropical Medicine, London, UK
| | | | - Come Z Koukpo
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | | | | | | | - Landry Assongba
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | | | - Tatchémè Filémon Tokponnon
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
- Ecole Polytechnique d'Abomey-Calavi, Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Clément Agbangla
- Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Germain Gil Padonou
- Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey-Calavi, Benin
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Louisa A Messenger
- Faculty of Infectious and Tropical Diseases, Department of Disease Control, The London School of Hygiene and Tropical Medicine, London, UK
- Department of Environmental and Occupational Health, School of Public Health, University of Nevada, Las Vegas, NV, 89154, USA
| | - Corine Ngufor
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
- Faculty of Infectious and Tropical Diseases, Department of Disease Control, The London School of Hygiene and Tropical Medicine, London, UK
| | - Jackie Cook
- Medical Research Council (MRC) International Statistics and Epidemiology, Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | | | - Natacha Protopopoff
- Faculty of Infectious and Tropical Diseases, Department of Disease Control, The London School of Hygiene and Tropical Medicine, London, UK
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Konkon AK, Padonou GG, Osse R, Salako AS, Zoungbédji DM, Sina H, Sovi A, Tokponnon F, Aïkpon R, Noukpo H, Baba-Moussa L, Akogbéto MC. Insecticide resistance status of Aedes aegypti and Aedes albopictus mosquitoes in southern Benin, West Africa. Trop Med Health 2023; 51:22. [PMID: 37085936 PMCID: PMC10122308 DOI: 10.1186/s41182-023-00514-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 04/09/2023] [Indexed: 04/23/2023] Open
Abstract
BACKGROUND The emergence of insecticide resistance in Aedes mosquitoes could undermine efforts to control arboviruses. The present study aims to assess in some communes of Southern Benin, the susceptibility level of Aedes aegypti (Linnaeus, 1762) and Aedes albopictus (Skuse, 1894) to insecticides commonly used in public health, as well as mechanisms involved. METHODS Females Ae. albopictus and Ae. aegypti collected in Ifangni, Porto-Novo, Avrankou, Adjarra and Kétou from June 2021 to October 2022, were exposed to: deltamethrin 0.05%, permethrin 0.75%, alpha-cypermethrin 0.05%, pirimiphos methyl 0.25% and bendiocarb 0.1%, following the standard WHO susceptibility tube test protocol. In some sites, pre-exposure to the synergist PBO was used to verify if pyrethroid resistance of populations of Aedes was mediated by oxidases. RESULTS Full susceptibility to deltamethrin and permethrin was observed in all tested populations of Ae. albopictus. However, with alphacypermethrin, a suspected resistance was observed in Adjarra (94.67%), Ifangni (93%) and Porto-Novo (94%), and a resistance in Avrankou (83%). The PBO-alphacypermethrin tests performed, led to a full susceptibility (100%) in all four sites, which confirms the full involvement of oxidases in resistance of all tested populations of Ae. albopictus to alphacypermethrin. At the opposite, Aedes aegypti was either resistant or suspected of being resistant to all tested pyrethroids in all four sites, except in Ifangni where a full susceptibility to alphacypermethrin was observed. The full susceptibility of Ae. aegypti to bendiocarb and pirimiphos-methyl in all communes suggests that these two insecticides can be good candidates for an effective control of pyrethroid-resistant Aedes vector populations. Use of permethrin and deltamethrin could also be considered for controlling populations of Ae. albopictus. CONCLUSION Results of the present study will help guide strategy to implement for an effective control of Aedes vector populations in Benin.
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Affiliation(s)
- Alphonse Keller Konkon
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Benin.
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin.
| | - Germain Gil Padonou
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Benin
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Razaki Osse
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Benin
- École de Gestion et d'exploitation des Systèmes d'élevage de l'Université Nationale d'Agriculture de Porto-Novo, Porto-Novo, Benin
| | | | - David Mahouton Zoungbédji
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Benin
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Haziz Sina
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
- Department of Biochemistry and Cellular Biology, Laboratory of Biology and Molecular Typing in Microbiology, University of Abomey-Calavi, Abomey-Calavi, Benin
| | - Arthur Sovi
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Benin
- Faculty of Agronomy, University of Parakou, Parakou, Benin
- Faculty of Infectious and Tropical Diseases, The London School of Hygiene and Tropical Medicine, London, UK
| | - Filemon Tokponnon
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Benin
| | - Rock Aïkpon
- Ministère de la Santé, 08 BP 882, Cotonou, Benin
- Université Nationale des Sciences, Technologies, Ingénierie Et Mathématiques (UNSTIM), Abomey, Benin
| | - Herbert Noukpo
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Benin
| | - Lamine Baba-Moussa
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
- Department of Biochemistry and Cellular Biology, Laboratory of Biology and Molecular Typing in Microbiology, University of Abomey-Calavi, Abomey-Calavi, Benin
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Pusawang K, Sattabongkot J, Saingamsook J, Zhong D, Yan G, Somboon P, Wongpalee SP, Cui L, Saeung A, Sriwichai P. Insecticide Susceptibility Status of Anopheles and Aedes Mosquitoes in Malaria and Dengue Endemic Areas, Thai-Myanmar Border. INSECTS 2022; 13:1035. [PMID: 36354859 PMCID: PMC9694411 DOI: 10.3390/insects13111035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/05/2022] [Accepted: 11/07/2022] [Indexed: 06/16/2023]
Abstract
The occurrence and spread of insecticide resistance has had a negative effect on the efficacy of insecticide-based tools and is distributed worldwide, including the Greater Mekong Subregion (GMS). This study aims to determine the insecticide susceptibility of malaria and dengue vectors in malaria and dengue hotspots on the Thai-Myanmar border. Mosquito larvae and pupae were obtained from water sources from December 2019 to April 2020 in Tha Song Yang District, Tak province, western Thailand. WHO bioassay susceptibility tests were conducted with three classes of insecticides to evaluate the knockdown and mortality rates of Anopheles and Aedes aegypti female adults. V1016G and F1534C kdr mutations in the voltage-gated sodium channel of Ae. aegypti were identified using a multiplex PCR. A total of 5764 female mosquitoes were bioassayed in this study, including Anopheles spp. (92.63%) and F1 Ae. aegypti (7.37%). After 24 h of observation, An. minimus s.l. (n = 3885) and An. maculatus s.l. (n = 1138) in Suan Oi (SO) and Tala Oka (TO) were susceptible to pyrethroids, organophosphates and carbamates (except bendiocarb) with 98-100% mortality (MR). Resistance to bendiocarb was detected with a mortality rate of 88.80%, 88.77%, and 89.92% for An. minimus s.l. (n = 125, 125) and An. maculatus s.l. (n = 66), respectively. The first generation of Ae. aegypti adult females were suspected of resistance to deltamethrin (n = 225, MR = 96.89%) and confirmed resistance to permethrin (n = 200, MR = 20.00%). V1016G and F1534C mutations were detected in three genotypes, heterozygote and homozygote forms. The correlation between the kdr alleles and deltamethrin resistance was significant. In conclusion, bendiocarb resistance was found in primary malaria vectors, An. minimus s.l. and An. maculatus s.l. F1 Ae. aegypti population was pyrethroids-resistant, associated with kdr alleles. Therefore, molecular analysis should be conducted to gain insights into the mechanism of insecticide resistance. Routine malaria vector control programmes, such as fogging implementation in hotspot villages to induce Aedes resistance available in peri-domestic sites, are questionable.
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Affiliation(s)
- Kanchon Pusawang
- Center of Insect Vector Study, Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Center, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Jassada Saingamsook
- Center of Insect Vector Study, Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Daibin Zhong
- Department of Population Health and Disease Prevention, University of California, Irvine, CA 92697, USA
| | - Guiyun Yan
- Department of Population Health and Disease Prevention, University of California, Irvine, CA 92697, USA
| | - Pradya Somboon
- Center of Insect Vector Study, Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Somsakul Pop Wongpalee
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Liwang Cui
- Division of Infectious Diseases, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
| | - Atiporn Saeung
- Center of Insect Vector Study, Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Patchara Sriwichai
- Department of Medical Entomology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
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Menze BD, Tchouakui M, Mugenzi LMJ, Tchapga W, Tchoupo M, Wondji MJ, Chiumia M, Mzilahowa T, Wondji CS. Marked aggravation of pyrethroid resistance in major malaria vectors in Malawi between 2014 and 2021 is partly linked with increased expression of P450 alleles. BMC Infect Dis 2022; 22:660. [PMID: 35907831 PMCID: PMC9338535 DOI: 10.1186/s12879-022-07596-9] [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: 03/28/2022] [Accepted: 06/27/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Increased intensity of pyrethroid resistance is threatening the effectiveness of insecticide-based interventions to control malaria in Africa. Assessing the extent of this aggravation and its impact on the efficacy of these tools is vital to ensure the continued control of major vectors. Here we took advantage of 2009 and 2014 data from Malawi to establish the extent of the resistance escalation in 2021 and assessed its impact on various bed nets performance. METHODS Indoor blood-fed and wild female Anopheles (An) mosquitoes were collected with an electric aspirator in Chikwawa. Cocktail and SINE PCR were used to identify sibling species belonging to An. funestus group and An. gambiae complex. The susceptibility profile to the four classes of insecticides was assessed using the WHO tubes bioassays. Data were saved in an Excel file. Analysis was done using Vassarstats and figures by Graph Pad. RESULTS In this study, a high level of resistance was observed with pyrethroids (permethrin, deltamethrin and alpha-cypermethrin with mortality rate at 5x discriminating concentration (DC) < 50% and Mortality rate at 10x DC < 70%). A high level of resistance was also observed to carbamate (bendiocarb) with mortality rate at 5x DC < 25%). Aggravation of resistance was also noticed between 2009 and 2021. For pyrethroids, the mortality rate for permethrin reduced from 47.2% in 2009 to 13% in 2014 and 6.7% in 2021. For deltamethrin, the mortality rate reduced from 42.3% in 2009 to 1.75% in 2014 and 5.2% in 2021. For Bendiocarb, the mortality rate reduced from 60% in 2009 to 30.1% in 2014 and 12.2% in 2021. The high resistance observed is consistent with a drastic loss of pyrethroid-only bed nets efficacy although Piperonyl butoxide (PBO)-based nets remain effective. The resistance pattern observed was linked with high up-regulation of the P450 genes CYP6P9a, CYP6P9b and CYP6M7 in An. funestus s.s. mosquitoes surviving exposure to deltamethrin at 1x, 5x and 10x DC. A significant association was observed between the 6.5 kb structural variant and resistance escalation with homozygote resistant (SV+/SV+) more likely to survive exposure to 5x and 10x (OR = 4.1; P < 0.001) deltamethrin than heterozygotes. However, a significant proportion of mosquitoes survived the synergist assays with PBO suggesting that other mechanisms than P450s are present. CONCLUSIONS This resistance aggravation in An. funestus s.s. Malawian population highlights an urgent need to deploy novel control tools not relying on pyrethroids to improve the effectiveness of vector control.
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Affiliation(s)
- Benjamin D Menze
- Medical Entomology Department, Centre for Research in Infectious Diseases (CRID), Yaoundé, Cameroon.
| | - Magellan Tchouakui
- Medical Entomology Department, Centre for Research in Infectious Diseases (CRID), Yaoundé, Cameroon
| | - Leon M J Mugenzi
- Medical Entomology Department, Centre for Research in Infectious Diseases (CRID), Yaoundé, Cameroon
| | - Williams Tchapga
- Medical Entomology Department, Centre for Research in Infectious Diseases (CRID), Yaoundé, Cameroon
| | - Micareme Tchoupo
- Medical Entomology Department, Centre for Research in Infectious Diseases (CRID), Yaoundé, Cameroon
| | - Murielle J Wondji
- Medical Entomology Department, Centre for Research in Infectious Diseases (CRID), Yaoundé, Cameroon
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Martin Chiumia
- Malaria Alert Centre (MAC), Kamuzu University of Health Sciences (KUHeS), Blantyre, Malawi
| | - Themba Mzilahowa
- Malaria Alert Centre (MAC), Kamuzu University of Health Sciences (KUHeS), Blantyre, Malawi
| | - Charles S Wondji
- Medical Entomology Department, Centre for Research in Infectious Diseases (CRID), Yaoundé, Cameroon.
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
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7
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Accrombessi M, Akogbeto MC, Dangbenon E, Akpovi H, Sovi A, Yovogan B, Adoha C, Assongba L, Ogouyemi-Hounto A, Padonou GG, Thickstun C, Rowland M, Ngufor C, Protopopoff N, Cook J. Malaria Burden and Associated Risk Factors in an Area of Pyrethroid-Resistant Vectors in Southern Benin. Am J Trop Med Hyg 2022; 107:tpmd220190. [PMID: 35895353 PMCID: PMC9490648 DOI: 10.4269/ajtmh.22-0190] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 04/24/2022] [Indexed: 11/28/2022] Open
Abstract
Malaria remains the main cause of morbidity and mortality in Benin despite the scale-up of long-lasting insecticidal nets (LLINs), indoor residual spraying, and malaria case management. This study aimed to determine the malaria burden and its associated risk factors in a rural area of Benin characterized by high net coverage and pyrethroid-resistant mosquito vectors. A community-based cross-sectional survey was conducted in three districts in southern Benin. Approximately 4,320 randomly selected participants of all ages were tested for malaria using rapid diagnostic tests within 60 clusters. Risk factors for malaria infection were evaluated using mixed-effect logistic regression models. Despite high population net use (96%), malaria infection prevalence was 43.5% (cluster range: 15.1-72.7%). Children (58.7%) were more likely to be infected than adults (31.2%), with a higher malaria prevalence among older children (5-10 years: 69.1%; 10-15 years: 67.9%) compared with young children (< 5 years: 42.1%); however, young children were more likely to be symptomatic. High household density, low socioeconomic status, young age (< 15 years), poor net conditions, and low net usage during the previous week were significantly associated with malaria infection. Malaria prevalence remains high in this area of intense pyrethroid resistance despite high net use. New classes of LLINs effective against resistant vectors are therefore crucial to further reduce malaria in this area.
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Affiliation(s)
- Manfred Accrombessi
- Faculty of Infectious and Tropical Diseases, Disease Control Department, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | | | - Hilaire Akpovi
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | - Arthur Sovi
- Faculty of Infectious and Tropical Diseases, Disease Control Department, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Boulais Yovogan
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | - Constantin Adoha
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | - Landry Assongba
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | - Aurore Ogouyemi-Hounto
- UER Parasitology Mycology, Health Science Faculty, Abomey-Calavi University; National Malaria Control Program, Ministry of Health, Cotonou, Benin
| | | | - Charles Thickstun
- School of Epidemiology and Public Health, Faculty of Medicine, University of Ottawa, Ottawa, Canada
| | - Mark Rowland
- Faculty of Infectious and Tropical Diseases, Disease Control Department, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Corine Ngufor
- Faculty of Infectious and Tropical Diseases, Disease Control Department, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Natacha Protopopoff
- Faculty of Infectious and Tropical Diseases, Disease Control Department, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Jackie Cook
- Medical Research Council (MRC) International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
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