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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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2
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Padonou GG, Zoungbédji DM, Sovi A, Salako AS, Konkon AK, Yovogan B, Adoha CJ, Odjo EM, Osse R, Sina H, Govoétchan R, Kpanou CD, Sagbohan HW, Baba-Moussa L, Akogbéto M. Trophic preferences of Anopheles coluzzii (Diptera: Culicidae): what implications for malaria vector control in Benin? JOURNAL OF MEDICAL ENTOMOLOGY 2023; 60:554-563. [PMID: 36939048 DOI: 10.1093/jme/tjad017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 01/14/2023] [Accepted: 02/03/2023] [Indexed: 05/13/2023]
Abstract
The main objective of the present study is to assess the preferences in terms of vertebrate hosts of Anopheles coluzzii, the main malaria vector in the pastoral area of Malanville, Benin, where rice cultivation and livestock are the main source of income for the populations. Adult mosquitoes were collected through pyrethrum spray catch, and human landing catch in two communes in Benin: Malanville, a pastoral area, and Porto-Novo, a nonpastoral area. Molecular species identification was performed through PCR within the Anopheles gambiae complex. Blood meal origin and P. falciparum sporozoite infection were determined using ELISA blood meal and circumsporozoite protein tests, respectively. Overall, 97% of females of An. gambiae s.l. were An. coluzzii, with biting behavior more pronounced outdoors in the pastoral area. In Malanville, the main vertebrate hosts on which females An. coluzzii blood fed were goats (44%), humans (24.29%), bovines (22%), and pigs (1.4%). Our results also showed that single-host blood meals (human: 24.29% or animal: 68%) were mostly observed compared to mixed blood meals (8.58%). The human biting rate (HBR) and P. falciparum sporozoite rate (SR) of An. coluzzii were 66.25 bites/man/night and 0.77%, respectively. However, in the nonpastoral zone (Porto-novo), 93.98% of samples were An. coluzzii. The latter blood-fed mostly (86.84%) on humans, with an estimated HBR of 21.53 b/m/n and SR of 5.81%. The present study revealed an opportunistic and zoophagic behavior of An. coluzzii in the Malanville area with an overall low mean SR.
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Affiliation(s)
- Germain Gil Padonou
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - David Mahouton Zoungbédji
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Arthur Sovi
- Centre de Recherche Entomologique de Cotonou (CREC), 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
| | | | - Alphonse Keller Konkon
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Boulais Yovogan
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Constantin Jesukèdè Adoha
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Esdras Mahoutin Odjo
- Centre de Recherche Entomologique de Cotonou (CREC), 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), Cotonou, Benin
- École de gestion et d'exploitation des systèmes d'élevage, Université Nationale d'Agriculture de Porto-Novo, Porto-Novo, Bénin
| | - Haziz Sina
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
- Laboratory of Biology and Molecular Typing in Microbiology, Department of Biochemistry and Cellular Biology, Abomey-Calavi, Benin
| | - Renaud Govoétchan
- Faculty of Agronomy, University of Parakou, Parakou, Benin
- Faculty of Infectious and Tropical Diseases, The London School of Hygiene and Tropical Medicine, London, UK
| | - Casimir Dossou Kpanou
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Hermann W Sagbohan
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Lamine Baba-Moussa
- Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
- Laboratory of Biology and Molecular Typing in Microbiology, Department of Biochemistry and Cellular Biology, Abomey-Calavi, Benin
| | - Martin Akogbéto
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
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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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Kpanou CD, Sagbohan HW, Sovi A, Osse R, Padonou GG, Salako A, Tokponnon F, Fassinou AJ, Yovogan B, Nwangwu UC, Adoha CJ, Odjo EM, Ahogni I, Sidick A, Saïd Baba-Moussa L, Akogbéto M. Assessing Insecticide Susceptibility and Resistance Intensity of Anopheles gambiae s.l. Populations From Some Districts of Benin Republic, West Africa. JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:949-956. [PMID: 35357491 DOI: 10.1093/jme/tjac037] [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: 10/21/2021] [Indexed: 06/14/2023]
Abstract
Pyrethroid resistance is widespread in sub-Saharan Africa. The objective of this study was to assess the insecticide resistance intensity in Anopheles gambiae s.l. (Diptera: Culicidae) in four districts of Benin in order to better understand how pyrethroid-only nets are likely to be effective. Thus, adult females of An. gambiae s.l., reared from field-collected larvae were used for assessing resistance intensity to permethrin and deltamethrin. They were tested at 1×, 5×, and 10× the diagnostic dose, using both WHO susceptibility tube testing and CDC bottle bioassays. Identification of molecular species, as well as of L1014F Kdr and Ace-1R mutations was performed using the PCR. The level of expression of biochemical enzymes was also evaluated. Overall, moderate to high resistance intensity to permethrin and deltamethrin was observed, irrespective of the testing method. While the L1014F Kdr frequency was high (>75%), Ace-1R was low (≤6%) in An. gambiaes.s. and Anopheles coluzzii, the two predominant species [52% (95% CI: 44.8-59.1) and 45% (95% CI: 38.0-52.2), respectively]. Anopheles arabiensis was found at very low frequency (3%, 95%CI: 1.1-6.4). For Biochemical analyses, α and β-esterases were over-expressed in all four districts, while mixed-function oxidases (MFOs) were over-expressed in only one. Overall, the two testing methods led to comparable conclusions, though there were a few inconsistencies between them. The moderate-high resistance intensity observed in the study area suggests that dual active-ingredient (AI) long-lasting insecticidal nets (LLINs) may provide better control of insecticide-resistant mosquitoes.
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Affiliation(s)
- Casimir Dossou Kpanou
- Département de Biologie des Vecteurs, Centre de Recherche entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Benin
- Département de Zoologie, Faculté des Sciences et Techniques, University of Abomey-Calavi, 01 BP 526 Abomey-Calavi, Benin
| | - Hermann W Sagbohan
- Département de Biologie des Vecteurs, Centre de Recherche entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Benin
- Département de Zoologie, Faculté des Sciences et Techniques, University of Abomey-Calavi, 01 BP 526 Abomey-Calavi, Benin
| | - Arthur Sovi
- Département de Biologie des Vecteurs, Centre de Recherche entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Benin
- Department of Sciences and Techniques for Animal and Fisheries Production, Faculty of Agronomy, University of Parakou, BP 123 Parakou, Benin
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, The London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK
| | - Razaki Osse
- Département de Biologie des Vecteurs, Centre de Recherche entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Benin
- Département des Sciences Animales et Halieutiques, École de gestion et d'exploitation des systèmes d'élevage, Université Nationale d'Agriculture de Porto-Novo, BP 43 Kétou, Bénin
| | - Gil G Padonou
- Département de Biologie des Vecteurs, Centre de Recherche entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Benin
- Département de Zoologie, Faculté des Sciences et Techniques, University of Abomey-Calavi, 01 BP 526 Abomey-Calavi, Benin
| | - Albert Salako
- Département de Biologie des Vecteurs, Centre de Recherche entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Benin
| | - Filémon Tokponnon
- Département de Biologie des Vecteurs, Centre de Recherche entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Benin
| | - Arsène Jacques Fassinou
- Département de Biologie des Vecteurs, Centre de Recherche entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Benin
| | - Boulais Yovogan
- Département de Biologie des Vecteurs, Centre de Recherche entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Benin
- Département de Zoologie, Faculté des Sciences et Techniques, University of Abomey-Calavi, 01 BP 526 Abomey-Calavi, Benin
| | - Udoka C Nwangwu
- Department of Disease Surveillance, National Arbovirus and Vectors Research Centre (NAVRC), 4 Park Ave, GRA 400102, Enugu, Nigeria
| | - Constantin J Adoha
- Département de Biologie des Vecteurs, Centre de Recherche entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Benin
- Département de Zoologie, Faculté des Sciences et Techniques, University of Abomey-Calavi, 01 BP 526 Abomey-Calavi, Benin
| | - Esdras Mahoutin Odjo
- Département de Biologie des Vecteurs, Centre de Recherche entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Benin
- Département de Zoologie, Faculté des Sciences et Techniques, University of Abomey-Calavi, 01 BP 526 Abomey-Calavi, Benin
| | - Idelphonse Ahogni
- Département de Biologie des Vecteurs, Centre de Recherche entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Benin
| | - Aboubakar Sidick
- Département de Biologie des Vecteurs, Centre de Recherche entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Benin
| | - Lamine Saïd Baba-Moussa
- Département de Zoologie, Faculté des Sciences et Techniques, University of Abomey-Calavi, 01 BP 526 Abomey-Calavi, Benin
| | - Martin Akogbéto
- Département de Biologie des Vecteurs, Centre de Recherche entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Benin
- Département de Zoologie, Faculté des Sciences et Techniques, University of Abomey-Calavi, 01 BP 526 Abomey-Calavi, Benin
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Bohounton RB, Djogbénou LS, Djihinto OY, Dedome OSL, Sovegnon PM, Barea B, Adomou A, Villeneuve P, Tchobo FP. Chemical composition and the insecticidal activity of Aeollanthus pubescens leaf essential oil against Anopheles gambiae sensu stricto. Parasit Vectors 2021; 14:518. [PMID: 34620224 PMCID: PMC8499547 DOI: 10.1186/s13071-021-05012-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 09/12/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The excessive use of synthetic insecticides is responsible for many cases of resistance in insects. Therefore, the use of natural molecules of ecological interest with insecticidal properties is an alternative approach to the use of synthetic insecticides. The aim of this study is to investigating the larvicidal and adulticidal activity and the chemical composition of the essential oil of Aeollanthus pubescens on the major malaria vector, Anopheles gambiae. METHODS Three reference strains of Anopheles gambiae sensu stricto (Kisumu, Kiskdr and Acerkis) were used in this study. The leaves of A. pubescens were collected in southern Benin. The standard World Health Organisation (WHO) guidelines for larvicide evaluation were used, and the chemical composition of the essential oil was analysed by gas chromatography coupled to mass spectrometry. Adult mosquitoes of each strain were exposed to pieces of net coated with the essential oil for 3 min using the WHO cone bioassay method. Probit regression analysis was used to determine the concentrations that would kill 50 and 95% of each test population (LC50, LC95) and the knockdown time for 50 and 95% of each test population (KDT50, and KDT95). The difference between the mortality-dose regressions for the different strains was analysed using the likelihood ratio test (LRT). The log-rank test was performed to evaluate the difference in survival between the strains. RESULTS A total of 14 components were identified, accounting for 98.3% of total oil content. The major components were carvacrol (51.1%), thymyle acetate (14.0%) and ɣ-terpinene (10.6%). The essential oil showed larvicidal properties on the Kisumu, Acerkis and Kiskdr strains, with LC50 of 29.6, 22.9 and 28.4 ppm, respectively. With pieces of netting treated at 165 µg/cm2, the KDT50 of both Acerkis (1.71 s; Z = 3.34, P < 0.001) and Kiskdr (2.67 s; Z = 3.49, P < 0.001) individuals were significantly lower than that of Kisumu (3.8 s). The lifespan of the three mosquito strains decreased to 1 day for Kisumu (χ2 = 99, df = 1, P < 0.001), 2 days for Acerkis (χ2 = 117, df = 1, P < 0.001) and 3 days for Kiskdr (χ2 = 96.9, df = 1, P < 0.001). CONCLUSION Our findings show that A. pubescens essential oil has larvicide and adulticide properties against the malaria vector An. gambiae sensu stricto, suggesting that this essential oil may be a potential candidate for the control of the resistant malaria-transmitting vectors.
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Affiliation(s)
- Roméo Barnabé Bohounton
- Laboratory of Study and Research of Applied Chemistry, Polytechnic School of Abomey-Calavi, Cotonou, Benin
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey Calavi, Abomey-Calavi, Benin
| | - Luc Salako Djogbénou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey Calavi, Abomey-Calavi, Benin
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | | | | | - Pierre Marie Sovegnon
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey Calavi, Abomey-Calavi, Benin
| | | | - Aristide Adomou
- Laboratoire de Botanique Et Écologie Végétale (LaBEV), Faculté Des Sciences Et Techniques (FAST), University of Abomey-Calavi, Cotonou, Benin
| | | | - Fidèle Paul Tchobo
- Laboratory of Study and Research of Applied Chemistry, Polytechnic School of Abomey-Calavi, Cotonou, Benin
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6
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Kpanou CD, Sagbohan HW, Dagnon F, Padonou GG, Ossè R, Salako AS, Sidick A, Sewadé W, Sominahouin A, Condo P, Ahmed SH, Impoinvil D, Akogbéto M. Characterization of resistance profile (intensity and mechanisms) of Anopheles gambiae in three communes of northern Benin, West Africa. Malar J 2021; 20:328. [PMID: 34315480 PMCID: PMC8314583 DOI: 10.1186/s12936-021-03856-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 07/16/2021] [Indexed: 11/30/2022] Open
Abstract
Background The selection and the spread of insecticide resistance in malaria vectors to the main classes of insecticides used in vector control tools are a major and ongoing challenge to malaria vector control programmes. This study aimed to determine the intensity of vector resistance to insecticides in three regions of Benin with different agro-ecological characteristics. Methods Larvae of Anopheles gambiae sensu lato (s.l.) were collected from September to November 2017 in different larval sites in three northern Benin communes: Parakou, Kandi and Malanville. Two to five-day-old, non-blood-fed, female mosquitoes were exposed to papers impregnated with deltamethrin, permethrin and bendiocarb at dosages of 1 × the diagnostic dose, 5 × and 10 × to determine the intensity of resistance in these vectors. Molecular frequencies of the kdr L1014F and ace-1R G119S insecticide resistance mutations and levels of detoxification enzymes were determined for mosquitoes sampled at each study site. Results Resistance to pyrethroids (permethrin and deltamethrin) was recorded in all three communes with mortality rates below 60% using the diagnostic dose (1x). The results obtained after exposure of An. gambiae to permethrin 10 × were 99% in Kandi, 98% in Malanville and 99% in Parakou. With deltamethrin 10x, mortality rates were 100% in Kandi, 96% in Malanville and 73% in Parakou. For the diagnostic dose of bendiocarb, suspected resistance was recorded in the communes of Malanville (97%) and Kandi (94%) while sensitivity was observed in Parakou (98%).Using the 10 × dose, mortality was 98% in Kandi, 100% in Malanville and 99% in Parakou. The frequencies of the kdr L1014F allele varied between 59 and 83% depending on the sites and species of the An. gambiae complex, while the frequency of the ace-1R G119S gene varied between 0 and 5%. Biochemical tests showed high levels of oxidase and esterase activity compared to the susceptible colony strain of An. gambiae sensu stricto (Kisumu strain). Conclusion Anopheles gambiae showed a generalized loss of susceptibility to permethrin and deltamethrin but also showed moderate to high intensity of resistance in different regions of Benin. This high intensity of resistance is a potential threat to the effectiveness of vector control.
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Affiliation(s)
- Casimir Dossou Kpanou
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Bénin. .,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Bénin.
| | - Hermann W Sagbohan
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Bénin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Bénin
| | - Fortuné Dagnon
- US President's Malaria Initiative, US Agency for International Development, Cotonou, Bénin.,Bill & Melinda Gates Foundation, Lagos, Nigeria
| | - Germain G Padonou
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Bénin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Bénin
| | - Razaki Ossè
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Bénin.,Université Nationale d'Agriculture de Porto-Novo, Porto-Novo, Bénin
| | - Albert Sourou Salako
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Bénin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Bénin
| | - Aboubakar Sidick
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Bénin
| | - Wilfried Sewadé
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Bénin
| | - André Sominahouin
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Bénin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Bénin
| | - Patrick Condo
- US President's Malaria Initiative, US Agency for International Development, Cotonou, Bénin
| | - Saadani Hassani Ahmed
- US President's Malaria Initiative, US Agency for International Development, Cotonou, Bénin
| | - Daniel Impoinvil
- US President's Malaria Initiative, Centers for Disease Control and Prevention for Disease Control (CDC), Georgia, USA
| | - Martin Akogbéto
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Bénin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Bénin
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7
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Sagbohan HW, Kpanou CD, Osse R, Dagnon F, Padonou GG, Sominahouin AA, Salako AS, Sidick A, Sewade W, Akinro B, Ahmed S, Impoinvil D, Agbangla C, Akogbeto M. Intensity and mechanisms of deltamethrin and permethrin resistance in Anopheles gambiae s.l. populations in southern Benin. Parasit Vectors 2021; 14:202. [PMID: 33853655 PMCID: PMC8048290 DOI: 10.1186/s13071-021-04699-1] [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: 01/27/2021] [Accepted: 03/22/2021] [Indexed: 11/24/2022] Open
Abstract
Background Insecticide resistance is threatening the effectiveness of efforts to control malaria vectors in Benin. This study explores the levels and mechanisms of insecticide resistance in An. gambiae s.l. to pyrethroids. Methods Larvae were collected from August 2017 to July 2018 in five communes in southern Benin (Adjohoun, Allada, Bohicon, Cotonou, and Porto-Novo) representing diverse ecological regions, and were reared in Benin’s insectary. Two- to five-day-old female mosquitoes from each district were exposed to multiple doses of deltamethrin and permethrin (1×, 2×, 5×, and 10×) using the WHO insecticide resistance intensity bioassay. The effect of pre-exposure to the synergist, piperonyl butoxide (PBO), was also tested at different pyrethroid doses. Molecular allele frequencies of kdr (1014F) and ace-1R (119S) insecticide resistance mutations and levels of detoxification enzymes were determined for mosquitoes sampled from each study area. Results An. gambiae s.l. were resistant to pyrethroid-only exposure up to 10× the diagnostic doses in all the study sites for both deltamethrin and permethrin. Mortality was significantly higher in An. gambiae s.l. pre-exposed to PBO followed by exposure to deltamethrin or permethrin compared to mosquitoes exposed to deltamethrin or permethrin only (p < 0.001). The difference in mortality between deltamethrin only and PBO plus deltamethrin was the smallest in Cotonou (16–64%) and the greatest in Bohicon (12–93%). The mortality difference between permethrin only and PBO plus permethrin was the smallest in Cotonou (44–75%) and the greatest in Bohicon (22–72%). In all the study sites, the kdr resistance allele (1014F) frequency was high (75–100%), while the ace-1 resistance allele (G119S) frequency was low (0–3%). Analysis of the metabolic enzymatic activity of An. gambiae s.l. showed overexpression of nonspecific esterases and glutathione S-transferases (GST) in all study sites. In contrast to the PBO results, oxidase expression was low and was similar to the susceptible An. gambiae s.s. Kisumu strain in all sites. Conclusion There is high-intensity resistance to pyrethroids in southern Benin. However, pre-exposure to PBO significantly increased susceptibility to the pyrethroids in the different An. gambiae s.l. populations sampled. The use of PBO insecticide-treated bed nets may help maintain the gains in An. gambiae (s.l.) control in southern Benin. Graphical Abstract ![]()
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Affiliation(s)
- Hermann Watson Sagbohan
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin. .,Faculty of Science and Technology of the University of Abomey-Calavi, Godomey, Benin.
| | - Casimir D Kpanou
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin.,Faculty of Science and Technology of the University of Abomey-Calavi, Godomey, Benin
| | - Razaki Osse
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin.,National University of Agriculture of Porto-Novo, Porto-Novo, Benin
| | | | - Germain G Padonou
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin.,Faculty of Science and Technology of the University of Abomey-Calavi, Godomey, Benin
| | | | - Albert Sourou Salako
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin.,Faculty of Science and Technology of the University of Abomey-Calavi, Godomey, Benin
| | | | - Wilfried Sewade
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Bruno Akinro
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Saadani Ahmed
- US President's Malaria Initiative, US Agency for International Development, Cotonou, Benin
| | - Daniel Impoinvil
- US President's Malaria Initiative, Centers for Disease Control and Prevention (CDC), Atlanta, USA
| | - Clément Agbangla
- Faculty of Science and Technology of the University of Abomey-Calavi, Godomey, Benin.,Genetics and Biotechnology Laboratory of the UAC, Godomey, Benin
| | - Martin Akogbeto
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
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Hamid-Adiamoh M, Amambua-Ngwa A, Nwakanma D, D'Alessandro U, Awandare GA, Afrane YA. Insecticide resistance in indoor and outdoor-resting Anopheles gambiae in Northern Ghana. Malar J 2020; 19:314. [PMID: 32867769 PMCID: PMC7460795 DOI: 10.1186/s12936-020-03388-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 08/25/2020] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Selection pressure from continued exposure to insecticides drives development of insecticide resistance and changes in resting behaviour of malaria vectors. There is need to understand how resistance drives changes in resting behaviour within vector species. The association between insecticide resistance and resting behaviour of Anopheles gambiae sensu lato (s.l.) in Northern Ghana was examined. METHODS F1 progenies from adult mosquitoes collected indoors and outdoors were exposed to DDT, deltamethrin, malathion and bendiocarb using WHO insecticide susceptibility tests. Insecticide resistance markers including voltage-gated sodium channel (Vgsc)-1014F, Vgsc-1014S, Vgsc-1575Y, glutathione-S-transferase epsilon 2 (GSTe2)-114T and acetylcholinesterase (Ace1)-119S, as well as blood meal sources were investigated using PCR methods. Activities of metabolic enzymes, acetylcholine esterase (AChE), non-specific β-esterases, glutathione-S-transferase (GST) and monooxygenases were measured from unexposed F1 progenies using microplate assays. RESULTS Susceptibility of Anopheles coluzzii to deltamethrin 24 h post-exposure was significantly higher in indoor (mortality = 5%) than outdoor (mortality = 2.5%) populations (P = 0.02). Mosquitoes were fully susceptible to malathion (mortality: indoor = 98%, outdoor = 100%). Susceptibility to DDT was significantly higher in outdoor (mortality = 9%) than indoor (mortality = 0%) mosquitoes (P = 0.006). Mosquitoes were also found with suspected resistance to bendiocarb but mortality was not statistically different (mortality: indoor = 90%, outdoor = 95%. P = 0.30). Frequencies of all resistance alleles were higher in F1 outdoor (0.11-0.85) than indoor (0.04-0.65) mosquito populations, while Vgsc-1014F in F0 An. gambiae sensu stricto (s.s) was significantly associated with outdoor-resting behaviour (P = 0.01). Activities of non-specific β-esterase enzymes were significantly higher in outdoor than indoor mosquitoes (Mean enzyme activity: Outdoor = : 1.70/mg protein; Indoor = 1.35/mg protein. P < 0.0001). AChE activity was also more elevated in outdoor (0.62/mg protein) than indoor (0.57/mg protein) mosquitoes but this was not significant (P = 0.08). Human blood index (HBI) was predominantly detected in indoor (18%) than outdoor mosquito populations (3%). CONCLUSIONS The overall results did not establish that there was a significant preference of resistant malaria vectors to solely rest indoors or outdoors, but varied depending on the resistant alleles present. Phenotypic resistance was higher in indoor than outdoor-resting mosquitoes, but genotypic and metabolic resistance levels were higher in outdoor than the indoor populations. Continued monitoring of changes in resting behaviour within An. gambiae s.l. populations is recommended.
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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, Ghana
- Medical Research Council Unit, The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, Gambia
| | - Alfred Amambua-Ngwa
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP) and Department of Biochemistry, Cell and Molecular, University of Ghana, Legon, Ghana
- Medical Research Council Unit, The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, Gambia
| | - Davis Nwakanma
- Medical Research Council Unit, The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, Gambia
| | - Umberto D'Alessandro
- Medical Research Council Unit, The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, Gambia
| | - Gordon A Awandare
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP) and Department of Biochemistry, Cell and Molecular, University of Ghana, Legon, Ghana
| | - Yaw A Afrane
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP) and Department of Biochemistry, Cell and Molecular, University of Ghana, Legon, Ghana.
- Department of Medical Microbiology, College of Health Sciences, University of Ghana, Legon, Accra, Ghana.
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Aïkpon RY, Padonou G, Dagnon F, Ossè R, Ogouyemi Hounto A, Tokponon F, Aïkpon G, Lyikirenga L, Akogbéto M. Upsurge of malaria transmission after indoor residual spraying withdrawal in Atacora region in Benin, West Africa. Malar J 2020; 19:3. [PMID: 31900182 PMCID: PMC6942255 DOI: 10.1186/s12936-019-3086-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 12/21/2019] [Indexed: 11/23/2022] Open
Abstract
Background In Benin, malaria vector control mostly relies on long-lasting, insecticidal-treated bed nets (LLINs) and indoor residual spraying (IRS) operations. From 2011 to 2016, an IRS programme has been implemented in Atacora region. However, in 2017 the programme was withdrawn from two other regions in the northern part of the country, with hopes that gains would be relatively sustained because of the seasonality of malaria transmission. What would be the vulnerability of populations to malaria after the withdrawal of IRS? Methods Monthly mosquito collections were performed through human landing captures (HLCs) for 24 months (from January to December 2016 during the last IRS campaign, and from January to December 2018, 2 years after the withdrawal of IRS). Vector mosquitoes biting density was sampled by HLC and was tested for presence of Plasmodium falciparum sporozoites. The carcass of these mosquitoes (abdomens, wing, legs) were subjected to molecular species identification using polymerase chain reaction (PCR) assays. Results It is noticed a drastic increase (~ 3 times higher) of vector abundance after the withdrawal of IRS. Mosquito biting rates in the 3 survey districts increased significantly after IRS was withdrawn. In 2018, after IRS cessation a significant increase of entomological inoculation rate was recorded, where each inhabitant received an average of 94.9 infected bites/year to 129.21 infected bites/year against an average of 17.15 infected bites/year to 24.82 infected bites/year in 2016. Conclusion It is obvious that the withdrawal of IRS confers a vulnerability of the population with regard to the malaria transmission. Robust monitoring is needed to better understand when and where IRS should be most adequate, or can be safely withdrawn. In case of withdrawal, adapted accompanying measures should be proposed according to the context not only to maintain the gains capitalized with IRS, but also to avoid any rebound of transmission.
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Affiliation(s)
- Rock Yves Aïkpon
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. .,Ecole Normale Supérieure de Natitingou (ENS), Natitingou, Benin. .,Université Nationale des Sciences, Technologies, Ingénierie et Mathématiques (UNSTIM), Abomey, Benin.
| | - Gil Padonou
- Ecole Normale Supérieure de Natitingou (ENS), Natitingou, Benin.,Université d'Abomey-Calavi, Cotonou, Benin
| | - Fortuné Dagnon
- US President's Malaria Initiative, US Agency for International Development, Cotonou, Benin
| | - Razaki Ossè
- Ecole Normale Supérieure de Natitingou (ENS), Natitingou, Benin.,Université Nationale d'Agriculture (UNA), Ketou, Benin
| | - Aurore Ogouyemi Hounto
- Faculté des Sciences de la Santé (FSS), Cotonou, Benin.,Programme National de Lutte Contre le Paludisme, Cotonou, Benin
| | | | | | | | - Martin Akogbéto
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
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10
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Salako AS, Dagnon F, Sovi A, Padonou GG, Aïkpon R, Ahogni I, Syme T, Govoétchan R, Sagbohan H, Sominahouin AA, Akinro B, Iyikirenga L, Agossa F, Akogbeto MC. Efficacy of Actellic 300 CS-based indoor residual spraying on key entomological indicators of malaria transmission in Alibori and Donga, two regions of northern Benin. Parasit Vectors 2019; 12:612. [PMID: 31888730 PMCID: PMC6937814 DOI: 10.1186/s13071-019-3865-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 12/19/2019] [Indexed: 11/25/2022] Open
Abstract
Background The current study shows the results of three years of IRS entomological monitoring (2016, before intervention; 2017 and 2018, after intervention) performed in Alibori and Donga, northern Benin. Methods Mosquito collections were performed on a monthly basis using human landing catches and pyrethrum spray catches in six districts including four treated with Actellic 300 CS (Kandi, Gogounou, Djougou and Copargo) and two untreated (Bembèrèkè and Kouandé) which served as control sites. Key transmission indicators of Anopheles gambiae (s.l.) as well as the residual activity of Actellic 300 CS assessed through WHO cone tests, were determined. Results The residual efficacy duration of Actellic 300 CS after the two IRS campaigns (2017 and 2018) was 4–5 months (May–September). The parity rate and the sporozoite index of An. gambiae (s.l.) were 36.62% and 0.71%, respectively, after the first spray round in treated areas compared to 57.24% and 3.7%, respectively, in the control areas (P < 0.0001). The same trend was observed after the second spray round. After the first spray round, each person received 1.6 infective bites/month (ib/m) in the treated areas against 12.11 ib/m in the control areas, resulting in a reduction rate of 86.78%. Similarly, the entomological inoculation rate was 1.5 ib/m after the second spray round in the treated areas vs 9.75 ib/m in the control areas, corresponding to a reduction of 84.61%. A decrease in the parity rate (46.26%), sporozoite index (85.75%) and EIR (87.27%) was observed for An. gambiae (s.l.) after the first round of IRS (June–October 2017) compared to the pre-intervention period (June–October 2016). The density of An. gambiae (s.l.) ranged between 0.38–0.48 per house in treated areas vs 1.53–1.76 An. gambiae (s.l.) per house respectively after the first and second IRS rounds. Conclusions This study showed the positive impact of IRS in reducing key entomological parameters of malaria transmission in Alibori and Donga. However, the considerable blood-feeding rate of An. gambiae (s.l.) in spray areas, stress the need for the population to sleep under long-lasting insecticidal nets (LLINs) in addition, to prevent from mosquito bites which did not succeed in resting on sprayed walls.
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Affiliation(s)
- Albert Sourou Salako
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. .,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Cotonou, Benin.
| | - Fortune Dagnon
- USA President's Malaria Initiative, USA Agency for International Development, Cotonou, Benin
| | - Arthur Sovi
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,Faculty of Agronomy, University of Parakou, BP 123, Parakou, Benin.,Disease Control Department, Faculty of Infectious & Tropical Diseases, The London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Gil Germain Padonou
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Cotonou, Benin
| | - Rock Aïkpon
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,Université Nationale des Sciences, Technologies, Ingénierie et Mathématiques, Abomey, Bénin
| | - Idelphonse Ahogni
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Cotonou, Benin
| | - Thomas Syme
- Disease Control Department, Faculty of Infectious & Tropical Diseases, The London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Renaud Govoétchan
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,Faculty of Agronomy, University of Parakou, BP 123, Parakou, Benin
| | - Herman Sagbohan
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Cotonou, Benin
| | - André Aimé Sominahouin
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences Humaines et Sociales de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Bruno Akinro
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | | | - Fiacre Agossa
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.,PMI VectorLink Project, Abt Associates, Kinshasa, Democratic Republic of Congo
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11
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Salako AS, Ossè R, Padonou GG, Dagnon F, Aïkpon R, Kpanou C, Sagbohan H, Sovi A, Sèzonlin M, Akogbeto MC. Population Dynamics of Anopheles gambiae s.l. and Culex quinquefasciatus in Rural and Urban Settings Before an Indoor Residual Spraying Campaign in Northern Benin. Vector Borne Zoonotic Dis 2019; 19:674-684. [PMID: 30964413 PMCID: PMC6716193 DOI: 10.1089/vbz.2018.2409] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Background: The purpose of this report is to provide information on Culicidae diversity; biting behavior and spatio-seasonal variation of abundance of Anopheles gambiae s.l. and Culex quinquefasciatus in rural and urban settings of the Alibori and Donga regions, Northern Benin, where an indoor residual spraying (IRS) campaign to control malaria is planned. Methods: Both human landing catches, associated with pyrethrum spray catches were used to monitor the mosquito populations in 12 sites with 1 urban and 1 rural located in each of the 6 districts randomly selected in the two targeted regions. After morphological identification of all mosquito specimens, biting behavior and density of An. gambiae s.l. and Cx quinquefasciatus were studied. PCR was also performed on An. gambiae s.l., to identify sibling species and its seasonal variation. Results: A total of 10,367 mosquitoes were captured, related to 14 species of the genera, Anopheles, Aedes, Culex and Mansonia. Of the total species collection, 40.39% were An. gambiae s.l. and 56.85% were Cx. quinquefasciatus. An. gambiae s.l. was more abundant in Donga (2521 specimens) compared with Alibori (1666 specimens). The opposite trend was observed with Cx. quinquefasciatus (2162 specimens in Donga against 4028 in Alibori). An. gambiae s.l. was predominant and displayed a higher blood feeding rate in rural areas, whereas Cx. quinquefasciatus was in majority in urban areas. An. gambiae s.l. was more endophagic, whereas Cx. quinquefasciatus showed similar indoor and outdoor biting behavior. An. gambiae s.l. was composed of An. coluzzii found in majority in the drought, and An. gambiae, which was predominant in the rainy season. Conclusion: The predominance of the malaria vector, An. gambiae s.l. and their higher blood feeding rate and their significantly high endophagy in rural areas indicate that these areas should be primarily targeted with the IRS operations to have a substantial impact on malaria transmission. Endophagy, characteristic of An. gambiae s.l. in our study area, suggests that IRS will have a positive impact on vector control if implemented 1 week before June that is the onset of the rainy season.
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Affiliation(s)
- Albert Sourou Salako
- Vector Ecology Department, Center for Research in Entomology of Cotonou, Cotonou, Benin
- Department of Zoology, Faculty of Sciences and Techniques, University of Abomey Calavi, Abomey Calavi, Benin
| | - Razaki Ossè
- Vector Ecology Department, Center for Research in Entomology of Cotonou, Cotonou, Benin
- Laboratory of Animal and Fishery Sciences, School of Management and Exploitation of Livestock Systems, National University of Agriculture, Ketou, Benin
| | - Gil G. Padonou
- Vector Ecology Department, Center for Research in Entomology of Cotonou, Cotonou, Benin
- Department of Zoology, Faculty of Sciences and Techniques, University of Abomey Calavi, Abomey Calavi, Benin
| | - Fortuné Dagnon
- U.S. President's Malaria Initiative, US Agency for International Development, Cotonou, Benin
| | - Rock Aïkpon
- Vector Ecology Department, Center for Research in Entomology of Cotonou, Cotonou, Benin
- Biology Department, Superior Normal School, National University of Sciences, Technology, Engineering and Mathematics, Abomey, Benin
| | - Casimir Kpanou
- Vector Ecology Department, Center for Research in Entomology of Cotonou, Cotonou, Benin
- Department of Zoology, Faculty of Sciences and Techniques, University of Abomey Calavi, Abomey Calavi, Benin
| | - Hermann Sagbohan
- Vector Ecology Department, Center for Research in Entomology of Cotonou, Cotonou, Benin
- Department of Zoology, Faculty of Sciences and Techniques, University of Abomey Calavi, Abomey Calavi, Benin
| | - Arthur Sovi
- Vector Ecology Department, Center for Research in Entomology of Cotonou, Cotonou, Benin
| | - Michel Sèzonlin
- Department of Zoology, Faculty of Sciences and Techniques, University of Abomey Calavi, Abomey Calavi, Benin
| | - Martin C. Akogbeto
- Vector Ecology Department, Center for Research in Entomology of Cotonou, Cotonou, Benin
- Department of Zoology, Faculty of Sciences and Techniques, University of Abomey Calavi, Abomey Calavi, Benin
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12
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Koukpo CZ, Fassinou AJYH, Ossè RA, Agossa FR, Sovi A, Sewadé WT, Aboubakar S, Assogba BS, Akogbeto MC, Sezonlin M. The current distribution and characterization of the L1014F resistance allele of the kdr gene in three malaria vectors (Anopheles gambiae, Anopheles coluzzii, Anopheles arabiensis) in Benin (West Africa). Malar J 2019; 18:175. [PMID: 31113418 PMCID: PMC6528306 DOI: 10.1186/s12936-019-2808-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 05/10/2019] [Indexed: 11/14/2022] Open
Abstract
Background The fight against malaria faces various biological obstacles, including the resistance of parasites to anti-malarial drugs and the resistance of mosquito vectors to insecticides. The resistance of Anopheles gambiae sensu lato (s.l.) to pyrethroids, the only class of insecticides used to impregnate mosquito nets, is known in Benin; the expansion of this resistance is influenced by the existence of gene flow between species, otherwise by the presence or absence of the kdr mutation in them. The objective of this study is to determine the spatial distribution of An. gambiae and the level of expression of the pyrethroid resistance kdr gene in seven agro-ecological zones of Benin. Methods The study was conducted in 18 localities belonging to seven agro-ecological zones where environmental parameters varied. The sites represent the main areas of eco-epidemiological malaria in Benin. Anopheles gambiae larvae were collected in natural breeding sites using ladles and dipping method and reared under standard conditions. These larvae were reared under standard conditions of temperature and humidity (26 to 30 °C and 60 to 90%) at the insectarium of the Centre de Recherche Entomologique de Cotonou (CREC). Adult female mosquitoes having emerged are morphologically and molecularly identified. Homozygous resistant (1014F/1014F), homozygous sensitive (1014L/1014L) and heterozygous (1014F/1014L) genotypes of the L1014Fkdr gene mutation are determined by PCR. Results A total of 677 An. gambiae was subjected at the PCR. The results revealed the presence of three vector species of the An. gambiae complex, of which 409 Anopheles coluzzii, 259 An.gambiae, 5 hybrids (An. coluzzii/An. gambiae) and 4 Anopheles arabiensis in the different agro-ecological zones. The four An. arabiensis were only found in Dassa, a locality in the cotton zone of central Benin. The frequency of distribution of the L1014F allele of the kdr gene varies from 84.48 to 100% in An. gambiae, from 80 to 100% in An. coluzzii and from 0 to 75% in An. arabiensis in the different agro-ecological zones. Moreover, a significant difference is generally observed in the distribution of the L1014F allele (P < 0.05). By comparing in pairs the distribution frequencies of this allele in the two species by agro-ecological zone, only a significant difference is noted in the central cotton and fishery zones (P = 0.0496). Conclusion In summary, even if the data are in small portions, the An. Arabiensis species was found only in central Benin and the L1014F allele of the kdr gene is widespread and seems to fix in all the species recorded in the different agro-ecological zones. This situation amplifies the problem of resistance, which could eventually be a significant obstacle for the malaria vectors control. Similarly, a study of their genetic structure via the L1014F allele is necessary in order to put in place strategies to manage this resistance. These strategies will take into account both the ecology and the genetic diversity of the organisms involved to preserve the effectiveness of pyrethroids, the only insecticides used for the impregnation of mosquito nets.
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Affiliation(s)
- Come Z Koukpo
- Cotonou Entomological Research Centre (CREC), Cotonou, Benin. .,School Doctoral Sciences of Life and Earth, FAST-UAC, Abomey-Calavi, Benin.
| | - Arsène Jacques Y H Fassinou
- Cotonou Entomological Research Centre (CREC), Cotonou, Benin.,School Doctoral Sciences of Life and Earth, FAST-UAC, Abomey-Calavi, Benin
| | - Razaki A Ossè
- Cotonou Entomological Research Centre (CREC), Cotonou, Benin.,Ecole de Gestion Et D'Exploitation Des Systèmes D'Elevage, Université Nationale D'Agriculture, Kétou, Benin
| | - Fiacre R Agossa
- Cotonou Entomological Research Centre (CREC), Cotonou, Benin
| | - Arthur Sovi
- Cotonou Entomological Research Centre (CREC), Cotonou, Benin
| | | | | | - Bénoît S Assogba
- Regional Institute of Public Health, University of Abomey Calavi, 01BP918, Abomey Calavi, Benin
| | - Martin C Akogbeto
- Cotonou Entomological Research Centre (CREC), Cotonou, Benin.,Laboratory Evolution, Biodiversity of Arthropods and Sanitation, FAST-UAC, Abomey-Calavi, Benin
| | - Michel Sezonlin
- Cotonou Entomological Research Centre (CREC), Cotonou, Benin.,Laboratory Evolution, Biodiversity of Arthropods and Sanitation, FAST-UAC, Abomey-Calavi, Benin
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13
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Salako AS, Ahogni I, Aïkpon R, Sidick A, Dagnon F, Sovi A, Sominahouin AA, Agossa F, Iyikirenga L, Akogbeto MC. Insecticide resistance status, frequency of L1014F Kdr and G119S Ace-1 mutations, and expression of detoxification enzymes in Anopheles gambiae (s.l.) in two regions of northern Benin in preparation for indoor residual spraying. Parasit Vectors 2018; 11:618. [PMID: 30509288 PMCID: PMC6278060 DOI: 10.1186/s13071-018-3180-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 10/30/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND This study aims to provide baseline data on the resistance status to insecticides, the frequency of mechanisms involved and the impact of the association with the synergist piperonyl butoxide (PBO) on resistant Anopheles gambiae (s.l.) populations in two regions of northern Benin, prior to an indoor residual spraying campaign and introduction of next generation long-lasting insecticidal nets (LLINs) incorporating PBO. METHODS Adult Anopheles gambiae (s.l.) originating from larvae collected in two study regions (Alibori within the Kandi-Gogounou-Segbana districts and Donga within the Djougou-Copargo-Ouake districts) were tested with impregnated papers (bendiocarb 0.1%, pirimiphos-methyl 0.25%, permethrin 0.75% and deltamethrin 0.05%). The synergist PBO was used to check for the involvement of detoxification enzymes in pyrethroid resistant populations. Molecular analyses were performed for the identification of species within the Anopheles gambiae (s.l.) complex and kdr L1014F and G119S Ace-1 mutations. Biochemical assays assessed the activity of detoxification enzymes. RESULTS Anopheles gambiae (s.l.) was resistant to pyrethroids, with a mortality range of 25-83% with deltamethrin and 6-55% with permethrin. A significant increase in mortality was observed after pre-exposure to PBO for both deltamethrin (63-99%) and permethrin (56-99%). With bendiocarb, An. gambiae (s.l.) were susceptible in Kandi (99% mortality), with possible resistance (92-95%) recorded in Djougou, Copargo, Gogounou, Ouake and Segbana. All study populations were fully susceptible to pirimiphos-methyl. The frequencies of resistant mutations varied according to species and sites: 0.67-0.88 for L1014F kdr and 0-0.06 for G119S Ace-1. Three study locations (Djougou, Gogounou and Kandi) showed high oxidase activity and four sites (Djougou, Ouake, Copargo and Kandi) showed elevated esterase activity. CONCLUSIONS This study confirms resistance to pyrethroids and suggests emerging bendiocarb resistance in An. gambiae (s.l.) populations in northern Benin. However, recovery of susceptibility to pyrethroids after PBO exposure, and susceptibility to organophosphates in the An. gambiae (s.l.) populations indicate that next generation LLINs incorporating PBO synergist combined with an indoor residual spraying (IRS) campaign with organophosphate insecticides may be regarded as alternative control tools.
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Affiliation(s)
- Albert Sourou Salako
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin. .,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin.
| | - Idelphonse Ahogni
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Rock Aïkpon
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,Technologies, Ingénierie et Mathématiques, Université Nationale des Sciences, Abomey, Bénin
| | - Aboubakar Sidick
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin
| | - Fortune Dagnon
- US Agency for International Development, US President's Malaria Initiative, Cotonou, Benin
| | - Arthur Sovi
- PMI VectorLink project, Abt associates, Bamako, Mali
| | - André Aimé Sominahouin
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences Humaines et Sociales de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Fiacre Agossa
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin
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14
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Salako AS, Ahogni I, Kpanou C, Sovi A, Azondekon R, Sominahouin AA, Tokponnon F, Gnanguenon V, Dagnon F, Iyikirenga L, Akogbeto MC. Baseline entomologic data on malaria transmission in prelude to an indoor residual spraying intervention in the regions of Alibori and Donga, Northern Benin, West Africa. Malar J 2018; 17:392. [PMID: 30373576 PMCID: PMC6206707 DOI: 10.1186/s12936-018-2507-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Accepted: 10/06/2018] [Indexed: 11/16/2022] Open
Abstract
Background Despite the success of indoor residual insecticide spraying (IRS) in Africa, particularly in Benin, some gaps of information need to be filled to optimize the effectiveness of this intervention in the perspective of the country’s effort to eliminate malaria. In anticipation to the 2018 IRS campaign in two targeted regions of northern Benin, this study aimed, to collect baseline information on vector composition, spatio-temporal variation and peak malaria transmission in the Alibori and Donga, two targeted regions of northern Benin. Information collected will help to better plan the implementation and later on the impact assessment of this IRS campaign. Methods The study was carried out in four districts of the two IRS targeted regions of northern Benin. Human landing catches and pyrethrum spray catches protocols were used to assess the biting rate (HBR) and, biting/resting behaviour of malaria vector populations. After morphological identification of collected Anopheles, the heads and thoraxes of Anopheles gambiae sensu lato (s.l.) were analysed by the ELISA CSP tests to estimate the sporozoite index (SI). The entomological inoculation rate was calculated as the product of mosquito biting rate (HBR) and the SI. Results The biting rates of An. gambiae s.l., the major vector in this study sites, varied significantly from region to region. It was higher: in rural than in urban areas, in rainy season than in dry season, indoors than outdoors. Overall, SI was comparable between sites. The highest EIRs were observed in the Donga region (16.84 infectious bites/man/month in Djougou district and 17.64 infectious bites/man/month in Copargo district) and the lowest in the Alibori region (10.74 infectious bites/man/month at Kandi district and 11.04 infectious bites/man/month at Gogounou district). Conclusion This study showed the heterogeneous and various nature of malaria epidemiology in Northern Benin. Indeed, the epidemiological profile of malaria transmission in the Alibori and Donga regions is made of a single season of transmission interrupted by a dry season. This period of transmission is relatively longer in Donga region than in Alibori. This information can be used to guide the extension of IRS in the Alibori and in the Donga, by primarily targeting areas with short periods of transmission, and easy to cover.
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Affiliation(s)
- Albert S Salako
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin. .,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin.
| | - Idelphonse Ahogni
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Casimir Kpanou
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Arthur Sovi
- PMI VectorLink Project, Abt Associates, Bamako, Mali
| | - Roseric Azondekon
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,University of Wisconsin Milwaukee, Milwaukee, WI, USA
| | - André A Sominahouin
- Centre de Recherche entomologique de Cotonou (CREC), Cotonou, Benin.,Faculté des Sciences Humaines et Sociales de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | | | | | - Fortuné Dagnon
- US President's Malaria Initiative, US Agency for International Development, Cotonou, Benin
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15
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Djènontin A, Moiroux N, Bouraïma A, Zogo B, Sidick I, Corbel V, Pennetier C. Field efficacy of a new deltamethrin long lasting insecticidal net (LifeNet©) against wild pyrethroid-resistant Anopheles gambiae in Benin. BMC Public Health 2018; 18:947. [PMID: 30068334 PMCID: PMC6090760 DOI: 10.1186/s12889-018-5876-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 07/24/2018] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Malaria vector control is mostly based on Long-Lasting Insecticidal Nets (LLIN). To date, all LLINs fully recommended by the World Health Organization Pesticide Scheme (WHOPES) are made of polyester or polyethylene. In this context, a new LLIN named LifeNet©, made of polypropylene fiber is developed. According to the manufacturer, LifeNet©is made of soft filament, has a greater mechanical strength, a superior insecticide wash resistance with a short insecticide regeneration time, a better flammability profile and a better environmental profile compared to polyester or polyethylene nets. METHODS Through a WHOPES supervised trial, the efficacy of LifeNet© was evaluated in Benin in experimental huts against free-flying wild mosquitoes. RESULTS LifeNet© has equal or better performances in terms of wash resistance, exophily, blood feeding inhibition and mortality compared to conventionally treated nets (CTN) treated with deltamethrin at 25 mg/m2 and washed to just before exhaustion. CONCLUSIONS The efficacy of LifeNet© observed in this trial indicates that this net fulfill World Health Organization Pesticide Scheme (WHOPES) requirement for Long Lasting technology in Phase II. Throughout a Phase III trial currently ongoing in Southern Benin, the durability and the acceptability of this long-lasting insecticidal mosquito nets will be assessed under community conditions.
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Affiliation(s)
- Armel Djènontin
- Faculté des Sciences et Techniques-Université d’Abomey-Calavi, Cotonou, Benin
- MIVEGEC, IRD, CNRS, Univ Montpellier, Cotonou, Benin
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | - Nicolas Moiroux
- MIVEGEC, IRD, CNRS, Univ Montpellier, Montpellier, France
- IRSS, CNRST, Bobo Dioulasso, Ouagadougou, Burkina Faso
| | - Aziz Bouraïma
- MIVEGEC, IRD, CNRS, Univ Montpellier, Cotonou, Benin
| | - Barnabas Zogo
- MIVEGEC, IRD, CNRS, Univ Montpellier, Cotonou, Benin
| | | | - Vincent Corbel
- MIVEGEC, IRD, CNRS, Univ Montpellier, Montpellier, France
| | - Cédric Pennetier
- MIVEGEC, IRD, CNRS, Univ Montpellier, Montpellier, France
- IPR, INSP, Bouaké, Côte d’Ivoire
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16
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Cohen JM, Le Menach A, Pothin E, Eisele TP, Gething PW, Eckhoff PA, Moonen B, Schapira A, Smith DL. Mapping multiple components of malaria risk for improved targeting of elimination interventions. Malar J 2017; 16:459. [PMID: 29132357 PMCID: PMC5683539 DOI: 10.1186/s12936-017-2106-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 11/02/2017] [Indexed: 11/13/2022] Open
Abstract
There is a long history of considering the constituent components of malaria risk and the malaria transmission cycle via the use of mathematical models, yet strategic planning in endemic countries tends not to take full advantage of available disease intelligence to tailor interventions. National malaria programmes typically make operational decisions about where to implement vector control and surveillance activities based upon simple categorizations of annual parasite incidence. With technological advances, an enormous opportunity exists to better target specific malaria interventions to the places where they will have greatest impact by mapping and evaluating metrics related to a variety of risk components, each of which describes a different facet of the transmission cycle. Here, these components and their implications for operational decision-making are reviewed. For each component, related mappable malaria metrics are also described which may be measured and evaluated by malaria programmes seeking to better understand the determinants of malaria risk. Implementing tailored programmes based on knowledge of the heterogeneous distribution of the drivers of malaria transmission rather than only consideration of traditional metrics such as case incidence has the potential to result in substantial improvements in decision-making. As programmes improve their ability to prioritize their available tools to the places where evidence suggests they will be most effective, elimination aspirations may become increasingly feasible.
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Affiliation(s)
- Justin M Cohen
- Clinton Health Access Initiative, 383 Dorchester Ave., Suite 400, Boston, MA, 02127, USA.
| | - Arnaud Le Menach
- Clinton Health Access Initiative, 383 Dorchester Ave., Suite 400, Boston, MA, 02127, USA
| | - Emilie Pothin
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051, Basel, Switzerland
| | - Thomas P Eisele
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health and Tropical Medicine, 1440 Canal St (2300), New Orleans, LA, 70112, USA
| | - Peter W Gething
- Oxford Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7LF, UK
| | - Philip A Eckhoff
- Institute for Disease Modeling, Building IV, 3150 139th Ave SE, Bellevue, WA, 98005, USA
| | - Bruno Moonen
- Bill & Melinda Gates Foundation, PO Box 23350, Seattle, WA, 98102, USA
| | | | - David L Smith
- Institute for Health Metrics and Evaluation, University of Washington, 2301 Fifth Ave., Suite 600, Seattle, WA, 98121, USA
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17
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Djouaka R, Akoton R, Tchigossou GM, Atoyebi SM, Irving H, Kusimo MO, Djegbe I, Riveron JM, Tossou E, Yessoufou A, Wondji CS. Mapping the distribution of Anopheles funestus across Benin highlights a sharp contrast of susceptibility to insecticides and infection rate to Plasmodium between southern and northern populations. Wellcome Open Res 2016. [PMID: 28191507 DOI: 10.12688/wellcomeopenres.10213.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background. Malaria remains an important public health issue in Benin, with Anopheles gambiae s.l. and Anopheles funestus s.s being the predominant vectors. This study was designed to generate information on An. funestus distribution, molecular speciation, Plasmodium infection rate and insecticide susceptibility status across Benin. Methods. Mosquito samples were collected from December 2014 to January 2016 in 46 localities in Benin. These samples were mapped and An. funestus collected were speciated to the molecular level. Plasmodium infection rate was determined using a Taqman assay and susceptibility to insecticides was assessed using the WHO guidelines. The genotyping of the L119F- Gste2 mutation was also carried out. Results. An. funestus was found in 8 out of the 46 localities surveyed with a high presence in Tanongou (wet Sudanese ecological zone), Kpome, Doukonta and Pahou (sub-equatorial ecological zone). Molecular identifications revealed that only An. funestuss.s was present in southern Benin, whereas in Tanongou (northern Benin) An. funestus s.s. and An. leesoni were found in sympatry at proportions of 77.7% and 22.3% respectively. Plasmodium infection rate of An. funestus was higher in southern Benin at a range of 13 to 18% compared to 5.6% recorded in Tanongou. High DDT (8±0.5%) and permethrin (11±0.5%) resistance were observed in Doukonta, Kpome and Pahou, contrasting with relatively low resistance profiles: mortality-DDT=90±3.18% and mortality-permethrin=100% in Tanongou. Genotyping analysis revealed high frequency of the resistant 119F allele in the South (Kpome and Doukonta) compared to the North (Tanongou). Discussion and Conclusion. The high presence of An. funestus in the South compared to the North could be due to favorable environmental and climatic conditions found in both regions. A significant Plasmodium infection rate was recorded across the country. A high resistance profile was recorded in the southern Benin; this raises the need for further investigations on resistance selection factors.
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Affiliation(s)
| | - Romaric Akoton
- International Institute of Tropical Agriculture, Cotonou, Benin.,University of Abomey-Calavi, Cotonou, Benin
| | - Genevieve M Tchigossou
- International Institute of Tropical Agriculture, Cotonou, Benin.,University of Abomey-Calavi, Cotonou, Benin
| | - Seun M Atoyebi
- International Institute of Tropical Agriculture, Cotonou, Benin.,Cell Biology and Genetics Unit, Department of Zoology, University of Ibadan, Ibadan, Nigeria
| | - Helen Irving
- Liverpool School of Tropical Medicine, Liverpool, UK
| | | | - Innocent Djegbe
- University of Sciences, Arts and Techniques of Natitingou, Ecole Normale Supérieure de Natitingou, Natitingou, Benin
| | | | - Eric Tossou
- International Institute of Tropical Agriculture, Cotonou, Benin.,University of Abomey-Calavi, Cotonou, Benin
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18
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Djouaka R, Akoton R, Tchigossou GM, Atoyebi SM, Irving H, Kusimo MO, Djegbe I, Riveron JM, Tossou E, Yessoufou A, Wondji CS. Mapping the distribution of Anopheles funestus across Benin highlights a sharp contrast of susceptibility to insecticides and infection rate to Plasmodium between southern and northern populations. Wellcome Open Res 2016; 1:28. [PMID: 28191507 PMCID: PMC5300096 DOI: 10.12688/wellcomeopenres.10213.2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2017] [Indexed: 11/20/2022] Open
Abstract
Background. Malaria remains an important public health issue in Benin, with Anopheles gambiae s.l. and Anopheles funestus s.s being the predominant vectors. This study was designed to generate information on An. funestus distribution, molecular speciation, Plasmodium infection rate and insecticide susceptibility status across Benin. Methods. Mosquito samples were collected from December 2014 to January 2016 in 46 localities in Benin. These samples were mapped and An. funestus collected were speciated to the molecular level. Plasmodium infection rate was determined using a Taqman assay and susceptibility to insecticides was assessed using the WHO guidelines. The genotyping of the L119F- Gste2 mutation was also carried out. Results. An. funestus was found in 8 out of the 46 localities surveyed with a high presence in Tanongou (wet Sudanese ecological zone), Kpome, Doukonta and Pahou (sub-equatorial ecological zone). Molecular identifications revealed that only An. funestuss.s was present in southern Benin, whereas in Tanongou (northern Benin) An. funestus s.s. and An. leesoni were found in sympatry at proportions of 77.7% and 22.3% respectively. Plasmodium infection rate of An. funestus was higher in southern Benin at a range of 13 to 18% compared to 5.6% recorded in Tanongou. High DDT (8±0.5%) and permethrin (11±0.5%) resistance were observed in Doukonta, Kpome and Pahou, contrasting with relatively low resistance profiles: mortality-DDT=90±3.18% and mortality-permethrin=100% in Tanongou. Genotyping analysis revealed high frequency of the resistant 119F allele in the South (Kpome and Doukonta) compared to the North (Tanongou). Discussion and Conclusion. The high presence of An. funestus in the South compared to the North could be due to favorable environmental and climatic conditions found in both regions. A significant Plasmodium infection rate was recorded across the country. A high resistance profile was recorded in the southern Benin; this raises the need for further investigations on resistance selection factors.
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Affiliation(s)
| | - Romaric Akoton
- International Institute of Tropical Agriculture, Cotonou, Benin
- University of Abomey-Calavi, Cotonou, Benin
| | - Genevieve M. Tchigossou
- International Institute of Tropical Agriculture, Cotonou, Benin
- University of Abomey-Calavi, Cotonou, Benin
| | - Seun M. Atoyebi
- International Institute of Tropical Agriculture, Cotonou, Benin
- Cell Biology and Genetics Unit, Department of Zoology, University of Ibadan, Ibadan, Nigeria
| | - Helen Irving
- Liverpool School of Tropical Medicine, Liverpool, UK
| | | | - Innocent Djegbe
- University of Sciences, Arts and Techniques of Natitingou, Ecole Normale Supérieure de Natitingou, Natitingou, Benin
| | | | - Eric Tossou
- International Institute of Tropical Agriculture, Cotonou, Benin
- University of Abomey-Calavi, Cotonou, Benin
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19
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Noukpo MH, Damien GB, Elanga-N'Dille E, Sagna AB, Drame PM, Chaffa E, Boussari O, Corbel V, Akogbéto M, Remoue F. Operational Assessment of Long-Lasting Insecticidal Nets by Using an Anopheles Salivary Biomarker of Human-Vector Contact. Am J Trop Med Hyg 2016; 95:1376-1382. [PMID: 27928087 DOI: 10.4269/ajtmh.15-0541] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 08/19/2016] [Indexed: 01/10/2023] Open
Abstract
The widespread implementation of long-lasting insecticidal nets (LLINs) is a major intervention method for malaria control. Although the LLINs coverage increases, information available on the physical integrity (PI) of implemented LLINs is incomplete. This study aimed to validate human IgG antibody (Ab) response to Anopheles gSG6-P1 salivary peptide antigen, previously demonstrated as a pertinent biomarker of human exposure to Anopheles bites, for evaluating the PI of LLINs in field conditions. We analyzed data from 262 randomly selected children (< 5 years of age) in health districts of Benin. Anti-gSG6-P1 IgG responses were assessed and compared with the PI of LLINs that these same children slept under, and evaluated by the hole index (HI). Specific IgG levels were positively correlated to LLINs HI (r = 0.342; P < 0.0001). According to antipeptide IgG level (i.e., intensity of vector exposure), two categories of LLINs PI were defined: 1) group "HI: [0, 100]" corresponding to LLINs with "good" PI and 2) "HI > 100" corresponding to LLINs with "bad" PI. These results suggest that human Ab response to salivary peptide could be a complementary tool to help defining a standardized threshold of efficacy for LLINs under field use.
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Affiliation(s)
- Mahoutin H Noukpo
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin.,UMR IRD 224-CNRS 5290-Universités Montpellier Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Cotonou, Bénin
| | - Georgia B Damien
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin.,UMR IRD 224-CNRS 5290-Universités Montpellier Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Cotonou, Bénin
| | - Emmanuel Elanga-N'Dille
- UMR IRD 224-CNRS 5290-Universités Montpellier Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Cotonou, Bénin
| | - André B Sagna
- Institut Pierre Richet (IPR), Institut Nationale de la Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Papa M Drame
- UMR IRD 224-CNRS 5290-Universités Montpellier Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Cotonou, Bénin
| | - Evelyne Chaffa
- Programme National de Lutte Contre le Paludisme (PNLP), Ministère de la Santé, Cotonou, Bénin
| | - Olayidé Boussari
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin.,UMR IRD 224-CNRS 5290-Universités Montpellier Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Cotonou, Bénin
| | - Vincent Corbel
- UMR IRD 224-CNRS 5290-Universités Montpellier Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Cotonou, Bénin.,Department of Entomology, Faculty of Agriculture at Kamphaeng Saen, Kasetsart University, Nakhon Pathom, Thailand
| | - Martin Akogbéto
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin.,Faculté des Sciences et Techniques (FAST), Université d'Abomey Calavi (UAC), Abomey, Bénin
| | - Franck Remoue
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin. .,UMR IRD 224-CNRS 5290-Universités Montpellier Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Cotonou, Bénin.,Institut Pierre Richet (IPR), Institut Nationale de la Santé Publique (INSP), Bouaké, Côte d'Ivoire
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20
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Damien GB, Djènontin A, Chaffa E, Yamadjako S, Drame PM, Ndille EE, Henry MC, Corbel V, Remoué F, Rogier C. Effectiveness of insecticidal nets on uncomplicated clinical malaria: a case-control study for operational evaluation. Malar J 2016; 15:102. [PMID: 26891758 PMCID: PMC4759848 DOI: 10.1186/s12936-016-1156-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 02/09/2016] [Indexed: 11/10/2022] Open
Abstract
Background In a context of large-scale implementation of malaria vector control tools, such as the distribution of long-lasting insecticide nets (LLIN), it is necessary to regularly assess whether strategies are progressing as expected and then evaluate their effectiveness. The present study used the case–control approach to evaluate the effectiveness of LLIN 42 months after national wide distribution. This study design offers an alternative to cohort study and randomized control trial as it permits to avoid many ethical issues inherent to them. Methods From April to August 2011, a case–control study was conducted in two health districts in Benin; Ouidah–Kpomasse–Tori (OKT) in the south and Djougou–Copargo–Ouake (DCO) in the north. Children aged 0–60 months randomly selected from community were included. Cases were children with a high axillary temperature (≥37.5 °C) or a reported history of fever during the last 48 h with a positive rapid diagnostic test (RDT). Controls were children with neither fever nor signs suggesting malaria with a negative RDT. The necessary sample size was at least 396 cases and 1188 controls from each site. The main exposure variable was “sleeping every night under an LLIN for the 2 weeks before the survey” (SL). The protective effectiveness (PE) of LLIN was calculated as PE = 1 − odds ratio. Results The declared SL range was low, with 17.0 and 27.5 % in cases and controls in the OKT area, and 44.9 and 56.5 % in cases and controls, in the DCO area, respectively. The declared SL conferred 40.5 % (95 % CI 22.2–54.5 %) and 55.5 % (95 % CI 28.2–72.4 %) protection against uncomplicated malaria in the OKT and the DCO areas, respectively. Significant differences in PE were observed according to the mother’s education level. Conclusion In the context of a mass distribution of LLIN, their use still conferred protection in up to 55 % against the occurrence of clinical malaria cases in children. Social factors, the poor use and the poor condition of an LLIN can be in disfavour with its effectiveness. In areas, where LLIN coverage is assumed to be universal or targeted at high-risk populations, case–control studies should be regularly conducted to monitor the effectiveness of LLIN. The findings will help National Malaria Control Programme and their partners to improve the quality of malaria control according to the particularity of each area or region as far as possible.
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Affiliation(s)
- Georgia Barikissou Damien
- IRD-UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.
| | - Armel Djènontin
- IRD-UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. .,Laboratoire Evolution, Biodiversité des Arthropodes et Assainissement, Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey-Calavi, Bénin.
| | - Evelyne Chaffa
- Programme National de Lutte contre le Paludisme (PNLP), Direction Nationale de la Santé Publique, Ministère de la Santé, Cotonou, Benin.
| | - Sandra Yamadjako
- IRD-UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.
| | - Papa Makhtar Drame
- UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Institut de Recherche pour le Développement (IRD), 34394, Montpellier, France. .,IRD-UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. .,Laboratory of Parasitic Diseases, NIAID, NIH, 4 Center Dr, Bethesda, MD, 20892-0425, USA.
| | - Emmanuel Elanga Ndille
- IRD-UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.
| | - Marie-Claire Henry
- IRD-UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.
| | - Vincent Corbel
- UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Institut de Recherche pour le Développement (IRD), 34394, Montpellier, France. .,IRD-UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.
| | - Franck Remoué
- UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Institut de Recherche pour le Développement (IRD), 34394, Montpellier, France. .,IRD-UMR MIVEGEC (IRD224-CNRS5290-Universités Montpellier 1 et 2), Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin.
| | - Christophe Rogier
- Institut Pasteur de Madagascar, Antananarivo, Madagascar. .,Institut de Recherche Biomédicale des Armées, Brétigny sur Orge, France. .,Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, UM 63, CNRS 7278, IRD 198, INSERM 1095, Aix-Marseille Université, Marseille, France.
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Akogbéto MC, Aïkpon RY, Azondékon R, Padonou GG, Ossè RA, Agossa FR, Beach R, Sèzonlin M. Six years of experience in entomological surveillance of indoor residual spraying against malaria transmission in Benin: lessons learned, challenges and outlooks. Malar J 2015; 14:242. [PMID: 26063497 PMCID: PMC4465467 DOI: 10.1186/s12936-015-0757-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 06/02/2015] [Indexed: 11/23/2022] Open
Abstract
Background From 2008 to 2013, a prevention intervention against malaria based on indoor residual spraying (IRS) was implemented in Benin. From 2008 to 2012, Ficam M®, a bendiocarb-containing product was used for house spraying, in association with pirimiphos methyl EC (Actellic EC) in 2013. This operation aimed to strengthen the effectiveness of treated nets so as to expedite the achievement of Millennium Development Goals (MDGs): the reduction of morbidity and mortality due to malaria by 75 % from 2000 to 2015. Methods Monitoring and evaluation (M&E) was implemented in order to evaluate the impact of IRS intervention on malaria transmission. Anopheles gambiae s.l. populations were sampled by human landing catch. In addition, window exit traps and pyrethrum spray catches were performed to assess exophagic behaviour of Anopheles vectors the main malaria vector in the treated areas. The residual activity of insecticide in the treated walls was also assessed using WHO bioassay test. Results The purpose of this project was to draw attention to new challenges and future prospects for the success of IRS in Benin. The main strength of the intervention was a large-scale operation in which more than 80 % of the houses were treated due to the strong adhesion of population. In addition, a significant reduction of the EIR in areas under IRS were observed. However, there were many challenges including the high cost of IRS implementation and the identification of suitable areas to implement IRS. This was because of the low and short residual effect of the insecticides recommended for IRS and the management strategy for vector resistance to insecticides. This indicated that challenges are accompanied by suggested solutions. For the cost of IRS to be accessible to states, then local organizations need to be created in partnership with the National Malaria Control Programme (NMCP) in order to ensure relevant planning and implementation of IRS. Conclusion As an anticipatory measure against vector resistance, this paper proposes various methods, such as periodic IRS based on a combination of two or three insecticides of different classes used in rotation every two or three years.
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Affiliation(s)
- Martin C Akogbéto
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Bénin. .,Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Bénin.
| | - Rock Y Aïkpon
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Bénin. .,Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Bénin.
| | - Roseric Azondékon
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Bénin. .,Université du Massachusetts Amherst, Amherst, MA, USA.
| | - Gil G Padonou
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Bénin. .,Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Bénin.
| | - Razaki A Ossè
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Bénin. .,Université d'Agriculture de Kétou, Kétou, Benin.
| | - Fiacre R Agossa
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Bénin. .,Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Bénin.
| | | | - Michel Sèzonlin
- Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Bénin.
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Niang EHA, Konaté L, Diallo M, Faye O, Dia I. Reproductive isolation among sympatric molecular forms of An. gambiae from inland areas of south-eastern Senegal. PLoS One 2014; 9:e104622. [PMID: 25098711 PMCID: PMC4123975 DOI: 10.1371/journal.pone.0104622] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 07/11/2014] [Indexed: 12/02/2022] Open
Abstract
The Anopheles gambiae species complex includes at least seven morphologically indistinguishable species, one of which, Anopheles gambiae sensu stricto, is the primary mosquito vector responsible for the transmission of malaria across sub-Saharan Africa. Sympatric ecological diversification of An. gambiae s.s. is in progress within this complex, leading to the emergence of at least two incipient species (the M and S molecular forms now recognized as good species and named An. coluzzii and An. gambiae respectively) that show heterogeneous levels of divergence in most parts of Africa. However, this process seems to have broken down in coastal areas of West Africa at the extreme edge of the distribution. We undertook a longitudinal study to describe An. gambiae s.s. populations collected from two inland transects with different ecological characteristics in south-eastern Senegal. Analysis of samples collected from 20 sites across these two transects showed the M and S molecular forms coexisted at almost all sampled sites. Overall, similar hybridization rates (2.16% and 1.86%) were recorded in the two transects; sites with relatively high frequencies of M/S hybrids (up to 7%) were clustered toward the north-western part of both transects, often near urban settings. Estimated inbreeding indices for this putative speciation event varied spatially (range: 0.52-1), with hybridization rates being generally lower than expected under panmictic conditions. Such observations suggest substantial reproductive isolation between the M and S molecular forms, and further support the ongoing process of speciation in these inland areas. According to a recent reclassification of the An. gambiae complex, the M and S molecular forms from this zone correspond to An. coluzzii and An. gambiae, respectively. There is considerable evidence that these molecular forms differ in their behavioural and ecological characteristics. Detailed study of these characteristics will allow the development and implementation of better insect control strategies for combating malaria.
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Affiliation(s)
- El Hadji Amadou Niang
- Unité d’Entomologie Médicale, Institut Pasteur de Dakar, Dakar, Sénégal
- Laboratoire d’Ecologie Vectorielle et Parasitaire, Université Cheikh Anta Diop de Dakar, Dakar, Sénégal
| | - Lassana Konaté
- Laboratoire d’Ecologie Vectorielle et Parasitaire, Université Cheikh Anta Diop de Dakar, Dakar, Sénégal
| | - Mawlouth Diallo
- Unité d’Entomologie Médicale, Institut Pasteur de Dakar, Dakar, Sénégal
| | - Ousmane Faye
- Laboratoire d’Ecologie Vectorielle et Parasitaire, Université Cheikh Anta Diop de Dakar, Dakar, Sénégal
| | - Ibrahima Dia
- Unité d’Entomologie Médicale, Institut Pasteur de Dakar, Dakar, Sénégal
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Aïkpon R, Sèzonlin M, Tokponon F, Okè M, Oussou O, Oké-Agbo F, Beach R, Akogbéto M. Good performances but short lasting efficacy of Actellic 50 EC Indoor Residual Spraying (IRS) on malaria transmission in Benin, West Africa. Parasit Vectors 2014; 7:256. [PMID: 24886499 PMCID: PMC4049441 DOI: 10.1186/1756-3305-7-256] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 05/25/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The National Malaria Control Program (NMCP) has been using pirimiphos methyl for the first time for indoor residual spraying (IRS) in Benin. The first round was a success with a significant decrease of entomological indicators of malaria transmission in the treated districts. We present the results of the entomological impact on malaria transmission. Entomologic parameters in the control area were compared with those in intervention sites. METHODS Mosquito collections were carried out in three districts in the Atacora-Dongo region of which two were treated with pirimiphos methyl (Actellic 50EC) (Tanguiéta and Kouandé) and the untreated (Copargo) served as control. Anopheles gambiae s.l. populations were sampled monthly by human landing catch. In addition, window exit traps and pyrethrum spray catches were performed to assess exophagic behavior of Anopheles vectors. In the three districts, mosquito collections were organized to follow the impact of pirimiphos methyl IRS on malaria transmission and possible changes in the behavior of mosquitoes. The residual activity of pirimiphos methyl in the treated walls was also assessed using WHO bioassay test. RESULTS A significant reduction (94.25%) in human biting rate was recorded in treated districts where an inhabitant received less than 1 bite of An. gambiae per night. During this same time, the entomological inoculation rate (EIR) dramatically declined in the treated area (99.24% reduction). We also noted a significant reduction in longevity of the vectors and an increase in exophily induced by pirimiphos methyl on An. gambiae. However, no significant impact was found on the blood feeding rate. Otherwise, the low residual activity of Actellic 50 EC, which is three months, is a disadvantage. CONCLUSION Pirimiphos methyl was found to be effective for IRS in Benin. However, because of the low persistence of Actellic 50EC used in this study on the treated walls, the recourse to another more residual formulation of pirimiphos methyl is required.
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Affiliation(s)
- Rock Aïkpon
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Bénin
- Faculté des Sciences et Techniques, Université d’Abomey Calavi, Abomey Calavi, Bénin
| | - Michel Sèzonlin
- Faculté des Sciences et Techniques, Université d’Abomey Calavi, Abomey Calavi, Bénin
| | - Filémon Tokponon
- National Malaria Control Programm (NMCP), Ministry of Health, Cotonou, Benin
| | - Mariam Okè
- National Malaria Control Programm (NMCP), Ministry of Health, Cotonou, Benin
| | - Olivier Oussou
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Bénin
| | - Frédéric Oké-Agbo
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Bénin
| | | | - Martin Akogbéto
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604 Cotonou, Bénin
- Faculté des Sciences et Techniques, Université d’Abomey Calavi, Abomey Calavi, Bénin
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Lees RS, Knols B, Bellini R, Benedict MQ, Bheecarry A, Bossin HC, Chadee DD, Charlwood J, Dabiré RK, Djogbenou L, Egyir-Yawson A, Gato R, Gouagna LC, Hassan MM, Khan SA, Koekemoer LL, Lemperiere G, Manoukis NC, Mozuraitis R, Pitts RJ, Simard F, Gilles JR. Review: Improving our knowledge of male mosquito biology in relation to genetic control programmes. Acta Trop 2014; 132 Suppl:S2-11. [PMID: 24252487 DOI: 10.1016/j.actatropica.2013.11.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 11/09/2013] [Indexed: 12/26/2022]
Abstract
The enormous burden placed on populations worldwide by mosquito-borne diseases, most notably malaria and dengue, is currently being tackled by the use of insecticides sprayed in residences or applied to bednets, and in the case of dengue vectors through reduction of larval breeding sites or larviciding with insecticides thereof. However, these methods are under threat from, amongst other issues, the development of insecticide resistance and the practical difficulty of maintaining long-term community-wide efforts. The sterile insect technique (SIT), whose success hinges on having a good understanding of the biology and behaviour of the male mosquito, is an additional weapon in the limited arsenal against mosquito vectors. The successful production and release of sterile males, which is the mechanism of population suppression by SIT, relies on the release of mass-reared sterile males able to confer sterility in the target population by mating with wild females. A five year Joint FAO/IAEA Coordinated Research Project brought together researchers from around the world to investigate the pre-mating conditions of male mosquitoes (physiology and behaviour, resource acquisition and allocation, and dispersal), the mosquito mating systems and the contribution of molecular or chemical approaches to the understanding of male mosquito mating behaviour. A summary of the existing knowledge and the main novel findings of this group is reviewed here, and further presented in the reviews and research articles that form this Acta Tropica special issue.
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Tokponnon FT, Ogouyémi AH, Sissinto Y, Sovi A, Gnanguenon V, Cornélie S, Adéothy AA, Ossè R, Wakpo A, Gbénou D, Oke M, Kinde-Gazard D, Kleinschmidt I, Akogbeto MC, Massougbodji A. Impact of long-lasting, insecticidal nets on anaemia and prevalence of Plasmodium falciparum among children under five years in areas with highly resistant malaria vectors. Malar J 2014; 13:76. [PMID: 24581394 PMCID: PMC3973997 DOI: 10.1186/1475-2875-13-76] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 02/23/2014] [Indexed: 11/17/2022] Open
Abstract
Background The widespread use of insecticide-treated nets (LLINs) leads to the development of vector resistance to insecticide. This resistance can reduce the effectiveness of LLIN-based interventions and perhaps reverse progress in reducing malaria morbidity. To prevent such difficulty, it is important to know the real impact of resistance in the effectiveness of mosquito nets. Therefore, an assessment of LLIN efficacy was conducted in malaria prevention among children in high and low resistance areas. Methods The study was conducted in four rural districts and included 32 villages categorized as low or high resistance areas in Plateau Department, south-western Benin. Larvae collection was conducted to measure vector susceptibility to deltamethrin and knockdown resistance (kdr) frequency. In each resistance area, around 500 children were selected to measure the prevalence of malaria infection as well as the prevalence of anaemia associated with the use of LLINs. Results Observed mortalities of Anopheles gambiae s.s population exposed to deltamethrin ranged from 19 to 96%. Knockdown resistance frequency was between 38 and 84%. The prevalence of malaria infection in children under five years was 22.4% (19.9-25.1). This prevalence was 17.3% (14.2-20.9) in areas of high resistance and 27.1% (23.5-31.1) in areas of low resistance (p = 0.04). Eight on ten children that were aged six - 30 months against seven on ten of those aged 31–59 months were anaemic. The anaemia observed in the six to 30-month old children was significantly higher than in the 31–59 month old children (p = 0.00) but no difference associated with resistance areas was observed (p = 0.35). The net use rate was 71%. The risk of having malaria was significantly reduced (p < 0.05) with LLIN use in both low and high resistance areas. The preventive effect of LLINs in high resistance areas was 60% (95% CI: 40–70), and was significantly higher than that observed in low resistance areas (p < 0.05). Conclusion The results of this study showed that the resistance of malaria vectors seems to date not have affected the impact of LLINs and the use of LLINs was highly associated with reduced malaria prevalence irrespective of resistance.
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Sternberg ED, Thomas MB. Local adaptation to temperature and the implications for vector-borne diseases. Trends Parasitol 2014; 30:115-22. [DOI: 10.1016/j.pt.2013.12.010] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 12/24/2013] [Accepted: 12/28/2013] [Indexed: 12/29/2022]
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Gnanguenon V, Azondekon R, Oke-Agbo F, Sovi A, Ossè R, Padonou G, Aïkpon R, Akogbeto MC. Evidence of man-vector contact in torn long-lasting insecticide-treated nets. BMC Public Health 2013; 13:751. [PMID: 23941585 PMCID: PMC3751135 DOI: 10.1186/1471-2458-13-751] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2013] [Accepted: 08/12/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Studies indicate that physical damage to long-lasting insecticide-treated nets (LLINs) occurs at a surprisingly rapid rate following net distribution. To what extent does such damage affect the impact of LLINs? Can vectors pass a compromised LLIN barrier to bite? Do more resistant vectors enter the insecticide-treated nets (ITNs) through holes? METHODS The study was carried out in three geo-locations. Two types of LLINs (polyester and polyethylene) with 'standardized' physical damage were compared with similarly damaged, but non-insecticidal (control) nets. The proportionate Holes Index (pHI) of each net was 276. Mosquitoes were captured inside the nets, identified taxonomically, and subjected to molecular analysis to estimate Knock-down resistance (Kdr) frequency. RESULTS The most commonly observed species was Anopheles gambiae, accounting for approximately 70% (1,076/1,550) of the total mosquitoes collected both in LLINs and non-insecticidal nets. When compared with controls, number of vectors captured in torn LLINs was significantly reduced. Nonetheless in a night, an average of 5 An. gambiae s.l could enter the damaged LLINs to bite. Similar numbers of resistant mosquitoes were collected in both LLINs and non-insecticidal (control) nets (p > 0.05). CONCLUSIONS At a pHI of 276, man-vector contact was observed in torn LLINs. The insecticide at the surface of LLINs could only reduce the number of vectors. Resistant mosquitoes have opportunity to enter both non-insecticidal (control) nets and LLINs to bite.
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Affiliation(s)
- Virgile Gnanguenon
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Faculte des Sciences et Techniques de l’Université d’Abomey-Calavi, Abomey-Calavi, Benin
| | - Roseric Azondekon
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- University of Massachusetts Amherst, Amherst, USA
| | | | - Arthur Sovi
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Faculte des Sciences et Techniques de l’Université d’Abomey-Calavi, Abomey-Calavi, Benin
| | - Razaki Ossè
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Faculte des Sciences et Techniques de l’Université d’Abomey-Calavi, Abomey-Calavi, Benin
| | - Gil Padonou
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Faculte des Sciences et Techniques de l’Université d’Abomey-Calavi, Abomey-Calavi, Benin
| | - Rock Aïkpon
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Faculte des Sciences et Techniques de l’Université d’Abomey-Calavi, Abomey-Calavi, Benin
| | - Martin C Akogbeto
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
- Faculte des Sciences et Techniques de l’Université d’Abomey-Calavi, Abomey-Calavi, Benin
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Aïkpon R, Agossa F, Ossè R, Oussou O, Aïzoun N, Oké-Agbo F, Akogbéto M. Bendiocarb resistance in Anopheles gambiae s.l. populations from Atacora department in Benin, West Africa: a threat for malaria vector control. Parasit Vectors 2013; 6:192. [PMID: 23803527 PMCID: PMC3698110 DOI: 10.1186/1756-3305-6-192] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 06/22/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Owing to pyrethroid resistance in An. gambiae, the carbamate and organophosphate insecticides are currently regarded as alternatives or supplements to pyrethroids for use on mosquito net treatments. Resistance monitoring is therefore essential to investigate the susceptibility of An. gambiae s.l to these alternative products. METHODS Two to three day old adult female Anopheles mosquitoes were reared from larvae collected in the five districts (Kouandé, Natitingou, Matéri, Péhunco, Tanguiéta) of the Atacora department. Mosquitoes were then exposed to WHO impregnated papers. The four treatments consisted of: carbamates (0.1% bendiocarb, 0.1% propoxur) and organophosphates (0.25% pirimiphosmethyl, 1% fenitrothion). PCR assays were run to determine the members of the An. gambiae complex, the molecular forms (M) and (S), as well as phenotypes for insensitive acetylcholinesterase (AChE1) due to ace-1(R) mutation. RESULTS Bioassays showed bendiocarb resistance in all populations of An. gambiae s.s. tested. Propoxur resistance was observed in Matéri, Péhunco and Tanguiéta, while it was suspected in Kouandé and Natitingou. As for the organophosphates, susceptibility to pirimiphos-methyl was assessed in all populations. Fenitrothion resistance was detected in Kouandé, Péhunco and Tanguiéta, while it was suspected in Matéri and Natitingou. The S-form was predominant in tested samples (94.44%). M and S molecular forms were sympatric but no M/S hybrids were detected. The ace-1(R) mutation was found in both S and M molecular forms with frequency from 3.6 to 12%. Although the homozygous resistant genotype was the most prevalent genotype among survivors, the genotypes could not entirely explain the bioassay results. CONCLUSION Evidence of bendiocarb resistance in An. gambiae populations is a clear indication that calls for the implementation of insecticide resistance management strategies. The ace-1(R) mutation could not entirely explain the resistance to bendiocarb observed and is highly suggestive of involvement of other resistance mechanisms such as metabolic detoxification.
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Affiliation(s)
- Rock Aïkpon
- Centre de Recherche Entomologique de Cotonou (CREC), 06 BP 2604, Cotonou, Bénin.
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Modelling the risk of being bitten by malaria vectors in a vector control area in southern Benin, west Africa. Parasit Vectors 2013; 6:71. [PMID: 23497700 PMCID: PMC3605808 DOI: 10.1186/1756-3305-6-71] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 03/06/2013] [Indexed: 01/18/2023] Open
Abstract
Background The diversity of malaria vector populations, expressing various resistance and/or behavioural patterns could explain the reduced effectiveness of vector control interventions reported in some African countries. A better understanding of the ecology and distribution of malaria vectors is essential to design more effective and sustainable strategies for malaria control and elimination. Here, we analyzed the spatio-temporal risk of the contact between humans and the sympatric An. funestus and both M and S molecular forms of An. gambiae s.s. in an area of Benin with high coverage of vector control measures with an unprecedented level of resolution. Methods Presence-absence data for the three vectors from 1-year human-landing collections in 19 villages were assessed using binomial mixed-effects models according to vector control measures and environmental covariates derived from field and remote sensing data. After 8-fold cross-validations of the models, predictive maps of the risk of the contact between humans and the sympatric An. funestus and both molecular M and S forms of An. gambiae s.s. were computed. Results Model validations showed that the An. funestus, An. gambiae M form, and S form models provided an excellent (Area Under Curve>0.9), a good (AUC>0.8), and an acceptable (AUC>0.7) level of prediction, respectively. The distribution area of the probability of contact between human and An. funestus largely overlaps that of An. gambiae M form but this latter showed important seasonal variation. An. gambiae S form also showed seasonal variation but with different ecological preferences. Landscape data were useful to discriminate between the species’ distributions. Conclusions These results showed that available remote sensing data could help in predicting the human-vector contact for several species of malaria vectors at a village level scale. The predictive maps showed seasonal and spatial variations in the risk of human-vector contact for all three vectors. Such maps could help Malaria Control Programmes to implement more effective vector control strategy by taking into account to the dynamics of malaria vector species.
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Tene Fossog B, Antonio-Nkondjio C, Kengne P, Njiokou F, Besansky NJ, Costantini C. Physiological correlates of ecological divergence along an urbanization gradient: differential tolerance to ammonia among molecular forms of the malaria mosquito Anopheles gambiae. BMC Ecol 2013; 13:1. [PMID: 23294940 PMCID: PMC3548750 DOI: 10.1186/1472-6785-13-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 12/27/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Limitations in the ability of organisms to tolerate environmental stressors affect their fundamental ecological niche and constrain their distribution to specific habitats. Evolution of tolerance, therefore, can engender ecological niche dynamics. Forest populations of the afro-tropical malaria mosquito Anopheles gambiae have been shown to adapt to historically unsuitable larval habitats polluted with decaying organic matter that are found in densely populated urban agglomerates of Cameroon. This process has resulted in niche expansion from rural to urban environments that is associated with cryptic speciation and ecological divergence of two evolutionarily significant units within this taxon, the molecular forms M and S, among which reproductive isolation is significant but still incomplete. Habitat segregation between the two forms results in a mosaic distribution of clinally parapatric patches, with the M form predominating in the centre of urban agglomerates and the S form in the surrounding rural localities. We hypothesized that development of tolerance to nitrogenous pollutants derived from the decomposition of organic matter, among which ammonia is the most toxic to aquatic organisms, may affect this pattern of distribution and process of niche expansion by the M form. RESULTS Acute toxicity bioassays indicated that populations of the two molecular forms occurring at the extremes of an urbanization gradient in Yaounde, the capital of Cameroon, differed in their response to ammonia. The regression lines best describing the dose-mortality profile differed in the scale of the explanatory variable (ammonia concentration log-transformed for the S form and linear for the M form), and in slope (steeper for the S form and shallower for the M form). These features reflected differences in the frequency distribution of individual tolerance thresholds in the two populations as assessed by probit analysis, with the M form exhibiting a greater mean and variance compared to the S form. CONCLUSIONS In agreement with expectations based on the pattern of habitat partitioning and exposure to ammonia in larval habitats in Yaounde, the M form showed greater tolerance to ammonia compared to the S form. This trait may be part of the physiological machinery allowing forest populations of the M form to colonize polluted larval habitats, which is at the heart of its niche expansion in densely populated human settlements in Cameroon.
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Affiliation(s)
- Billy Tene Fossog
- Institut de Recherche pour le Développement (IRD), Unité Mixte de Recherche MIVEGEC (UM1, UM2, CNRS 5290, IRD 224), Montpellier, France
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaounde, Cameroon
- Faculty of Sciences, University of Yaounde I, Yaounde, Cameroon
| | - Christophe Antonio-Nkondjio
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaounde, Cameroon
| | - Pierre Kengne
- Institut de Recherche pour le Développement (IRD), Unité Mixte de Recherche MIVEGEC (UM1, UM2, CNRS 5290, IRD 224), Montpellier, France
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaounde, Cameroon
| | - Flobert Njiokou
- Faculty of Sciences, University of Yaounde I, Yaounde, Cameroon
| | - Nora J Besansky
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Carlo Costantini
- Institut de Recherche pour le Développement (IRD), Unité Mixte de Recherche MIVEGEC (UM1, UM2, CNRS 5290, IRD 224), Montpellier, France
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaounde, Cameroon
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Liu C, Mauk MG, Hart R, Bonizzoni M, Yan G, Bau HH. A low-cost microfluidic chip for rapid genotyping of malaria-transmitting mosquitoes. PLoS One 2012; 7:e42222. [PMID: 22879919 PMCID: PMC3411743 DOI: 10.1371/journal.pone.0042222] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 07/02/2012] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Vector control is one of the most effective measures to prevent the transmission of malaria, a disease that causes over 600,000 deaths annually. Around 30-40 Anopheles mosquito species are natural vectors of malaria parasites. Some of these species cannot be morphologically distinguished, but have behavioral and ecological differences. Emblematic of this is the Anopheles gambiae species complex. The correct identification of vector species is fundamental to the development of control strategies and epidemiological studies of disease transmission. METHODOLOGY/PRINCIPAL FINDINGS An inexpensive, disposable, field-deployable, sample-to-answer, microfluidic chip was designed, constructed, and tested for rapid molecular identification of Anopheles gambiae and Anopheles arabiensis. The chip contains three isothermal amplification reactors. One test reactor operates with specific primers to amplify Anopheles gambiae DNA, another with specific primers for Anopheles arabiensis DNA, and the third serves as a negative control. A mosquito leg was crushed on an isolation membrane. Two discs, laden with mosquito tissue, were punched out of the membrane and inserted into the two test chambers. The isolated, disc-bound DNA served as a template in the amplification processes. The amplification products were detected with intercalating fluorescent dye that was excited with a blue light-emitting diode. The emitted light was observed by eye and recorded with a cell-phone camera. When the target consisted of Anopheles gambiae, the reactor containing primers specific to An. gambiae lit up while the other two reactors remained dark. When the target consisted of Anopheles arabiensis, the reactor containing primers specific to An. arabiensis lit up while the other two reactors remained dark. CONCLUSIONS/SIGNIFICANCE The microfluidic chip provides a means to identify mosquito type through molecular analysis. It is suitable for field work, allowing one to track the geographical distribution of mosquito populations and community structure alterations due to environmental changes and malaria intervention measures.
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Affiliation(s)
- Changchun Liu
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Michael G. Mauk
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Robert Hart
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Mariangela Bonizzoni
- College of Health Sciences, University of California Irvine, Irvine, California, United States of America
| | - Guiyun Yan
- College of Health Sciences, University of California Irvine, Irvine, California, United States of America
| | - Haim H. Bau
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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Adaptation to aridity in the malaria mosquito Anopheles gambiae: chromosomal inversion polymorphism and body size influence resistance to desiccation. PLoS One 2012; 7:e34841. [PMID: 22514674 PMCID: PMC3325948 DOI: 10.1371/journal.pone.0034841] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 03/09/2012] [Indexed: 11/19/2022] Open
Abstract
Chromosomal inversions are thought to confer a selective advantage in alternative habitats by protecting co-adapted alleles from recombination. The frequencies of two inversions (2La and 2Rb) of the afro-tropical malaria mosquito Anopheles gambiae change gradually along geographical clines, increasing in frequency with degree of aridity. Such clines can result from gene flow and local selection acting upon alternative karyotypes along the cline, suggesting that these inversions may be associated with tolerance to xeric conditions. Since water loss represents a major challenge in xeric habitats, it can be supposed that genes inside these inversions are involved in water homeostasis. To test this hypothesis, we compared the desiccation resistance of alternative karyotypes from a colonised 2Rb/2La polymorphic population of A. gambiae from Cameroon. The strain included only the molecular form S, one of the genetic units marking incipient speciation in this taxon. Day-old mosquitoes of both sexes were assayed individually for time to death in a dry environment and the karyotype of each was determined post-mortem using molecular diagnostic assays for each inversion. In agreement with expectations based on their eco-geographical distribution, we found that 2La homokaryotypes survived significantly longer (1.3 hours) than the other karyotypes. However, there was weak support for the effect of 2Rb on desiccation resistance. Larger mosquitoes survived longer than smaller ones. Median survival of females was greater than males, but the effect of sex on desiccation resistance was weakly supported, indicating that differential survival was correlated to differences between sexes in average size. We found weak evidence for a heterotic effect of 2La karyotype on size in females. These results support the notion that genes located inside the 2La inversion are involved in water balance, contributing towards local adaptation of A. gambiae to xeric habitats, beyond the adaptive value conferred by a larger body size.
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Akogbeto M, Padonou GG, Bankole HS, Gazard DK, Gbedjissi GL. Dramatic decrease in malaria transmission after large-scale indoor residual spraying with bendiocarb in Benin, an area of high resistance of Anopheles gambiae to pyrethroids. Am J Trop Med Hyg 2011; 85:586-93. [PMID: 21976555 DOI: 10.4269/ajtmh.2011.10-0668] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
In 2008, the National Malaria Control Program in Benin implemented a vector control intervention based on indoor residual spraying (IRS). Four districts of high resistance of Anopheles gambiae to pyrethroids were sprayed with bendiocarb. More than 350,000 inhabitants have been protected. Entomologic parameters in the control area were compared with those in intervention sites. The study has shown a drastic decrease in the An. gambiae biting rate in the sprayed areas. Results of an enzyme-linked immunosorbent assay were negative for Plasmodium falciparum antigen during the entire period of the intervention. No household members received infected bites (entomologic inoculation rate = 0 during January-July). Parous rates were low in areas covered by IRS because bendiocarb is not conducive to long-term mosquito survival. Bendiocarb was found to be a good alternative insecticide for IRS in Benin, in areas where An. gambiae has developed high resistance to pyrethroids.
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Djègbè I, Boussari O, Sidick A, Martin T, Ranson H, Chandre F, Akogbéto M, Corbel V. Dynamics of insecticide resistance in malaria vectors in Benin: first evidence of the presence of L1014S kdr mutation in Anopheles gambiae from West Africa. Malar J 2011; 10:261. [PMID: 21910856 PMCID: PMC3179749 DOI: 10.1186/1475-2875-10-261] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 09/12/2011] [Indexed: 11/10/2022] Open
Abstract
Background Insecticide resistance monitoring is essential to help national programmers to implement more effective and sustainable malaria control strategies in endemic countries. This study reported the spatial and seasonal variations of insecticide resistance in malaria vectors in Benin, West Africa. Methods Anopheles gambiae s.l populations were collected from October 2008 to June 2010 in four sites selected on the basis of different use of insecticides and environment. WHO susceptibility tests were carried out to detect resistance to DDT, fenitrothion, bendiocarb, permethrin and deltamethrin. The synergist piperonyl butoxide was used to assess the role of non-target site mechanisms in pyrethroid resistance. Anopheles gambiae mosquitoes were identified to species and to molecular M and S forms using PCR techniques. Molecular and biochemical assays were carried out to determine kdr and Ace.1R allelic frequencies and activity of the detoxification enzymes. Results Throughout the surveys very high levels of mortality to bendiocarb and fenitrothion were observed in An. gambiae s.l. populations. However, high frequencies of resistance to DDT and pyrethroids were seen in both M and S form of An. gambiae s.s. and Anopheles arabiensis. PBO increased the toxicity of permethrin and restored almost full susceptibility to deltamethrin. Anopheles gambiae s.l. mosquitoes from Cotonou and Malanville showed higher oxidase activity compared to the Kisumu susceptible strain in 2009, whereas the esterase activity was higher in the mosquitoes from Bohicon in both 2008 and 2009. A high frequency of 1014F kdr allele was initially showed in An. gambiae from Cotonou and Tori-Bossito whereas it increased in mosquitoes from Bohicon and Malanville during the second year. For the first time the L1014S kdr mutation was found in An. arabiensis in Benin. The ace.1R mutation was almost absent in An. gambiae s.l. Conclusion Pyrethroid and DDT resistance is widespread in malaria vector in Benin and both metabolic and target site resistance are implicated. Resistance was not correlated with a change of malaria species and/or molecular forms. The 1014S kdr allele was first identified in wild population of An. arabiensis hence confirming the expansion of pyrethroid resistance alleles in Africa.
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Affiliation(s)
- Innocent Djègbè
- Centre de Recherche Entomologique de Cotonou, 06 BP 2604, Cotonou, Bénin.
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Djogbénou L, Pasteur N, Akogbéto M, Weill M, Chandre F. Insecticide resistance in the Anopheles gambiae complex in Benin: a nationwide survey. MEDICAL AND VETERINARY ENTOMOLOGY 2011; 25:256-267. [PMID: 21155858 DOI: 10.1111/j.1365-2915.2010.00925.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Benin has embraced World Health Organization-recommended preventive strategies to control malaria. Its National Malaria Control Programme is implementing and/or coordinating various actions and conducting evaluation trials of mosquito control strategies. Mosquito control is based on the use of insecticide-treated nets and indoor residual spraying, but the efficacy of these strategies to control malaria vectors is endangered by insecticide resistance. Here, we present the results of a nationwide survey on the status of insecticide susceptibility and resistance in Anopheles gambiae s.l. (Diptera: Culicidae) carried out in Benin in 2006-2007 (i.e. before extensive vector control was undertaken). Overall, our study showed that the S molecular form of An. gambiae s.s. predominates and is widely distributed across the country, whereas the frequency of the M form shows a strong decline with increasing latitude. Susceptibility to DDT, permethrin, carbosulfan and chlorpyrifos-methyl was assessed; individual mosquitoes were identified for species and molecular forms, and genotyped for the kdr and ace-1 loci. Full susceptibility to chlorpyrifos-methyl was recorded and very few samples displayed resistance to carbosulfan. High resistance levels to permethrin were detected in most samples and almost all samples displayed resistance to DDT. The kdr-Leu-Phe mutation was present in all localities and in both molecular forms of An. gambiae s.s. Furthermore, the ace-1(R) mutation was predominant in the S form, but absent from the M form. By contrast, no target modification was observed in Anopheles arabiensis. Resistance in the An. gambiae S molecular form in this study seemed to be associated with agricultural practices. Our study showed important geographic variations which must be taken into account in the vector control strategies that will be applied in different regions of Benin. It also emphasizes the need to regularly monitor insecticide resistance across the country and to adapt measures to manage resistance.
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Affiliation(s)
- L Djogbénou
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin.
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Santolamazza F, Caputo B, Calzetta M, Vicente JL, Mancini E, Petrarca V, Pinto J, della Torre A. Comparative analyses reveal discrepancies among results of commonly used methods for Anopheles gambiaemolecular form identification. Malar J 2011; 10:215. [PMID: 21810255 PMCID: PMC3170251 DOI: 10.1186/1475-2875-10-215] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 08/02/2011] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Anopheles gambiae M and S molecular forms, the major malaria vectors in the Afro-tropical region, are ongoing a process of ecological diversification and adaptive lineage splitting, which is affecting malaria transmission and vector control strategies in West Africa. These two incipient species are defined on the basis of single nucleotide differences in the IGS and ITS regions of multicopy rDNA located on the X-chromosome. A number of PCR and PCR-RFLP approaches based on form-specific SNPs in the IGS region are used for M and S identification. Moreover, a PCR-method to detect the M-specific insertion of a short interspersed transposable element (SINE200) has recently been introduced as an alternative identification approach. However, a large-scale comparative analysis of four widely used PCR or PCR-RFLP genotyping methods for M and S identification was never carried out to evaluate whether they could be used interchangeably, as commonly assumed. RESULTS The genotyping of more than 400 A. gambiae specimens from nine African countries, and the sequencing of the IGS-amplicon of 115 of them, highlighted discrepancies among results obtained by the different approaches due to different kinds of biases, which may result in an overestimation of MS putative hybrids, as follows: i) incorrect match of M and S specific primers used in the allele specific-PCR approach; ii) presence of polymorphisms in the recognition sequence of restriction enzymes used in the PCR-RFLP approaches; iii) incomplete cleavage during the restriction reactions; iv) presence of different copy numbers of M and S-specific IGS-arrays in single individuals in areas of secondary contact between the two forms. CONCLUSIONS The results reveal that the PCR and PCR-RFLP approaches most commonly utilized to identify A. gambiae M and S forms are not fully interchangeable as usually assumed, and highlight limits of the actual definition of the two molecular forms, which might not fully correspond to the two A. gambiae incipient species in their entire geographical range. These limits are discussed and operational suggestions on the choice of the most convenient method for large-scale M- and S-form identification are provided, also taking into consideration technical aspects related to the epidemiological characteristics of different study areas.
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Affiliation(s)
- Federica Santolamazza
- Istituto Pasteur-Fondazione Cenci-Bolognetti, Dipartimento di Sanità Pubblica e Malattie Infettive, Università SAPIENZA, Piazzale Aldo Moro 5, 00185, Rome, Italy
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d'Almeida TCDA, Agboton-Zoumenou MA, Garcia A, Massougbodji A, Briand V, Imorou Y, Cottrell G. Field evaluation of the intermittent preventive treatment of malaria during pregnancy (IPTp) in Benin: evolution of the coverage rate since its implementation. Parasit Vectors 2011; 4:108. [PMID: 21679439 PMCID: PMC3135562 DOI: 10.1186/1756-3305-4-108] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 06/16/2011] [Indexed: 05/26/2023] Open
Abstract
Background Malaria is an important public health problem in Africa. Pregnant women are a vulnerable population and this disease can underlie an increased risk of low-birth weight newborns (< 2500 g); these women therefore need management during pregnancy. This was previously provided by chloroquine treatment, which, because of compliance problems and drug resistance, was replaced by intermittent preventive treatment with sulfadoxine-pyrimethamine (ITPp-SP) with two single doses taken after 16 weeks of amenorrhea, at least 4 weeks apart. This protocol was recommended by the World Health Organization (WHO) in 1998 and was initiated in Benin in 2006 after its political adoption in 2004. A retrospective longitudinal study was conducted in eight maternity hospitals in two geographical areas in Benin (in the south and north). The study investigated 2420 women who gave birth from 2005 to 2009. The antenatal cards of those women were randomly selected over 5 years with the aim of analyzing the IPT coverage in the study's maternity hospitals. Results The rate of IPT-SP coverage evolved from 3.7% in 2005 to 87.8% in 2009 for women who had received at least one dose and from 2.7% to 68.4% from 2005 to 2009 for those who had received complete ITP (two doses). Variability in the results was observed depending on the geographical area (north/south) and the type of area (rural/urban). Conclusions In total, application of IPT-SP 2-doses has rapidly evolved since 2005, but the objective of 80% IPT coverage has not yet been achieved throughout the country. Moreover, problems of drug shortage recurring in the field (reported by health staff) remain to be resolved.
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