30 results on '"Aïkpon R"'
Search Results
2. Evolution du profil entomologique et épidémiologique an après la mise en oeuvre de la pulvérisation intra domiciliaire (PID) dans la commune de Kouande et dans la commune contrôle De Copargo au Benin
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Makoutodé, Charles Patrick, Aholoukpè, B, Aïkpon, R, Akogbéto, M, Makoutodé, M, Audibert, Martine, Massougbodji, Achille, Ecole Doctorale Pluridisciplinaire Espace Culture et Développement, (Faculté des Lettres Arts et Sciences Humaines), University of Abomey Calavi (UAC), Ministère de la Santé (Ministère de la Santé), Ministère de la Santé, Centre de Recherche Entomologique de Cotonou (CREC), Institut Régional de Santé Publique de Ouidah (IRSP), Institut Régional de Santé Publique de Ouidah, Centre d'Études et de Recherches sur le Développement International (CERDI), Université d'Auvergne - Clermont-Ferrand I (UdA)-Centre National de la Recherche Scientifique (CNRS), Faculté des Sciences de la Santé de Cotonou (Faculté des Sciences de la Santé de Cotonou), Université d’Abomey-Calavi = University of Abomey Calavi (UAC), and Institut Régional de Santé Publique Comlan Alfred Quenum [Ouidah] (IRSP)
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paludisme ,Profil épidémiologique et entomologique ,Moustiquaire imprégnée d’insecticide à longue durée ,benin ,[SHS.ECO]Humanities and Social Sciences/Economics and Finance ,Pulvérisation intra domiciliaire - Abstract
Position du problème : Au Bénin, le paludisme a représenté en 2012, la première cause de consultation chez les enfants de moins de cinq ans (47,2%) et pour l’ensemble des personnes traitées en ambulatoire (42,3%). Son incidence parmi tous ceux qui ont fréquenté une structure de soins en 2012 est, respectivement, de 429 pour mille chez les enfants de moins de 5ans et de 170 pour mille pour l’ensemble des consultants. En vue d’améliorer ces indicateurs, le Programme National de Lutte contre le Paludisme (PNLP) a décidé de mettre en oeuvre, à titre expérimental, en complément à la moustiquaire imprégnée d’insecticide à longue durée (MIILD), la pulvérisation intra domiciliaire (PID) dans sept des neuf municipalités du département de l'Atacora, une des zones parmi les plus endémiques de paludisme au Bénin. La présente étude cherche à évaluer l’évolution du profil entomologique et épidémiologique un an après la mise en oeuvre de la PID dans la commune de Kouandé et dans la commune contrôle de Copargo.Méthode : Il s’agit d’une étude entomologique et épidémiologique, descriptive et comparative comportant une double démarche rétrospective (mai 2010 à mai 2011) et prospective réalisée pendant et après la PID (mai 2011 à mai 2012). La technique d’échantillonnage utilisée a été non probabiliste pour toutes les cibles. En ce qui concerne les données entomologiques, les moustiques ont été capturés par aspersion d’insecticide à l’intérieur des maisons et sur appâts humains. Une fiche de recueil a été conçue pour la collecte des données épidémiologiques aussi bien pour la phase rétrospective que pour la phase prospective.Résultats : Les résultats des études entomologiques montrent que, quelle que soit la saison, la transmission du paludisme est continue dans la commune de Kouandé et que l’effet du bendiocarb utilisé pour PID est faible après trois mois. En revanche, en toute saison, les taux de piqûre et d’infestation ont baissé en zone PID bien qu’on y a noté un développement de la résistance des moustiques aux carbomates (bendiocarb 0,1%). Au plan épidémiologique, la proportion de femmes enceintes à risque de paludisme, ayant bénéficié d’une MIILD au cours de la distribution de routine durant la CPN, a diminué à Kouandé-Centre et à Guilmaro après la mise en oeuvre de la PID. La même tendance a été observée en zone contrôle. Dans le même temps, l’incidence annuelle du paludisme dans les formations sanitaires (cas présumés ou confirmés) a significativement diminué après l’intervention à Kouandé-Centre et à Guilmaro alors qu’elle a significativement augmenté à Copargo-centre mais diminué à Pabégou. Enfin, on note que quel que soit le type de zone (urbain ou rural), le risque relatif (RR) est significativement inférieur à 1 (borne sup IC95% est respectivement 0,279
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- 2015
3. Malaria vector control
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Aïkpon, R., primary
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- 2014
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4. Evaluation of the efficacy of bendiocarb in indoor residual spraying against pyrethroid resistant malaria vectors in Benin: results of the third campaign
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Ossè Razaki, Aikpon Rock, Padonou Gil, Oussou Olivier, Yadouléton Anges, and Akogbéto Martin
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An.gambiae ,EIR ,Longevity ,IRS ,Bendiocarb ,Resistance ,Benin ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background Since 2008, the National Malaria Control Program (NMCP) has been engaged in the implementation of indoor residual spraying (IRS) in Benin. The first and second round was a success with a drastic decrease of malaria transmission in areas under IRS. We present here the results of the third round. The purpose of this study was to compare the results of the third round of IRS to those achieved during the first two rounds. A second success of IRS will enable the Government of Benin to extend the strategy to other areas. Methods Mosquito collections were carried out in the department of Ouémé where the homes of four districts were treated with bendiocarb. In these districts, more than 350 000 inhabitants were protected by IRS. A fifth untreated district served as control. In the five districts, mosquito collections were organized to follow the dynamics of malaria transmission and possible changes in the behavior of mosquitoes. Results A significant reduction in human biting rate was recorded after the third round of IRS, specifically in Adjohoun (89.78%), Dangbo (56.8%) and Missérété (93.22%) where an inhabitant received less than 2 bites of An. gambiae per night. During this same time, the entomological inoculation rate (EIR) declined dramatically in all areas under intervention (74.26% reduction). We also noted a significant reduction in longevity, the blood feeding rate of the vectors and an increase in exophily induced by bendiocarb on An. gambiae and Mansonia spp. Conclusion The present study showed, once again, the effectiveness of bendiocarb on anopheles populations resistant to pyrethroids. This product can be recommended in combination with other insecticides for the management of vector resistance to insecticides.
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- 2012
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5. Cotton pest management practices and the selection of pyrethroid resistance in Anopheles gambiae population in Northern Benin
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Yadouleton Anges, Martin Thibaud, Padonou Gil, Chandre Fabrice, Asidi Alex, Djogbenou Luc, Dabiré Roch, Aïkpon Rock, Boko Michel, Glitho Isabelle, and Akogbeto Martin
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Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background Pyrethroid insecticides, carbamate and organophosphate are the classes of insecticides commonly used in agriculture for crop protection in Benin. Pyrethroids remain the only class of insecticides recommended by the WHO for impregnation of bed nets. Unfortunately, the high level of pyrethroid resistance in Anopheles gambiae s.l., threatens to undermine the success of pyrethroid treated nets. This study focuses on the investigation of agricultural practices in cotton growing areas, and their direct impact on larval populations of An. gambiae in surrounding breeding sites. Methods The protocol was based on the collection of agro-sociological data where farmers were subjected to semi-structured questionnaires based on the strategies used for crop protection. This was complemented by bioassay tests to assess the susceptibility of malaria vectors to various insecticides. Molecular analysis was performed to characterize the resistance genes and the molecular forms of An. gambiae. Insecticide residues in soil samples from breeding sites were investigated to determine major factors that can inhibit the normal growth of mosquito larvae by exposing susceptible and resistant laboratory strains. Results There is a common use by local farmers of mineral fertilizer NPK at 200 kg/ha and urea at 50 kg/hectare following insecticide treatments in both the Calendar Control Program (CCP) and the Targeted Intermittent Control Program (TICP). By contrast, no chemicals are involved in Biological Program (BP) where farmers use organic and natural fertilizers which include animal excreta. Susceptibility test results confirmed a high resistance to DDT. Mean mortality of An. gambiae collected from the farms practicing CCP, TICP and BP methods were 33%, 42% and 65% respectively. An. gambiae populations from areas using the CCP and TICP programs showed resistance to permethrin with mortality of 50% and 58% respectively. By contrast, bioassay test results of An. gambiae from BP areas gave a high level of susceptibility to permethrin with an average mortality of 94%. Molecular analysis identified An. gambiae s.s, and An. arabiensis with a high predominance of An. gambiae s.s (90%). The two molecular forms, M and S, were also determined with a high frequency of the S form (96%). The Kdr gene seemed the main target- site resistance mechanism detected in CCP, TICP, and BP areas at the rates ranging from 32 to 78%. The frequency of ace-1R gene was very low (< 0.1). The presence of inhibiting factors in soil samples under insecticide treatments were found and affected negatively in delaying the development of An. gambiae larval populations. Conclusions This research shows that Kdr has spread widely in An. gambiae, mainly in CCP and TICP areas where pyrethroids are extensively used. To reduce the negative impact of pesticides use in cotton crop protection, the application of BP-like programs, which do not appear to select for vector resistance would be useful. These results could serve as scientific evidence of the spread of resistance due to a massive agricultural use of insecticides and contribute to the management of pesticides usage on cotton crops hence reducing the selection pressure of insecticides on An. gambiae populations.
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- 2011
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6. Bio-efficacy of Olyset ® Plus, PermaNet ® 3.0 and Interceptor ® G2 on pyrethroid-resistant populations of Anopheles gambiae s.l. prior to the June 2023 net distribution campaign in Benin, West Africa.
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Zoungbédji DM, Padonou GG, Sovi A, Konkon AK, Salako AS, Azondékon R, Sidick A, Ahouandjinou JM, Towakinou L, Ossè R, Aïkpon R, Affoukou C, Baba-Moussa L, and Akogbéto M
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Background: This study investigates the effectiveness of new-generation mosquito nets, like Olyset
® Plus and PermaNet® 3.0, and dual-action nets such as Interceptor® G2, against pyrethroid-resistant Anopheles gambiae mosquitoes following the 2023 mass distribution of long-lasting insecticidal nets in Benin., Methods: We tested wild mosquito populations from six communes in Benin against various pyrethroid (permethrin 0.75%, alphacypermethrin 0.05%, and deltamethrin 0.05%) using WHO tube tests. Additionally, we exposed mosquitoes to chlorfenapyr 100 µg/ml using the CDC bottle bioassay method. A subset of mosquitoes underwent biochemical and PCR tests to check the overexpression of metabolic enzymes and the Kdr L1014F mutation. We evaluated the effectiveness of Olyset® Plus, PermaNet® 3.0, and Interceptor® G2 nets using cone and tunnel tests on both laboratory and field populations of An. gambiae., Results: Overall, the highest mortality rate was 60% with pyrethroid and 98 to100% with chlorfenapyr. In cone tests, all three types of nets induced mortality rates above 80% in the susceptible laboratory strain of An. gambiae. Notably, Olyset® Plus showed the highest mortality rates for pyrethroid-resistant mosquitoes in cone tests, ranging from 81.03% (95% CI: 68.59-90.13) in Djougou to 96.08% (95% CI: 86.54-99.52) in Akpro-Missérété. PermaNet® 3.0 had variable rates, from 42.5% (95% CI: 27.04-59.11) in Djougou to 58.54% (95% CI: 42.11-73.68) in Porto-Novo. However, revealed good results for Interceptor® G2, with 94% (95% CI: 87.40-97.77) mortality and 89.09% blood sampling inhibition in local populations of An. gambiae. In comparison, Interceptor® had lower rates of 17% (95% CI: 10.23-25.82) and 60%, respectively., Conclusion: These results suggest that tunnel tests are effective for evaluating dual-active ingredient nets. Additionally, Interceptor® G2 and PBO nets like Olyset® Plus could be considered as alternatives against pyrethroid-resistant mosquitoes., (© 2024. The Author(s).)- Published
- 2024
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7. The frequency of kdr and ace-1 alleles in Anopheles gambiae s.l. before and during indoor residual spraying (IRS) implementation and four years after IRS withdrawal in three districts in Atacora, Benin.
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Odjo EM, Impoinvil D, Fassinou AJYH, Padonou GG, Aïkpon R, Salako AS, Sominahouin AA, Adoha C, Yovogan B, Osse R, Oussou O, Tokponnon F, Gnanguénon V, Hassani AS, and Akogbeto MC
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- Animals, Benin, Alleles, Acetylcholinesterase genetics, Mosquito Vectors genetics, Insecticide Resistance genetics, Carbamates pharmacology, Organophosphates pharmacology, Mosquito Control methods, Insecticides pharmacology, Anopheles genetics, Pyrethrins pharmacology, Phenylcarbamates
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Background: Indoor residual spraying (IRS) was first implemented in the Atacora department, Benin from 2011 to 2012 using bendiocarb (carbamate) followed by annual spraying with pirimiphos-methyl (organophosphate) from 2013 to 2018. Before and after IRS implementation in Atacora, standard pyrethroid insecticide-treated bed nets were the main method of vector control in the area. This study investigated the knockdown resistance (kdr) gene (L1014F) and the acetylcholinesterase (ace-1) gene (G119S), before and during IRS implementation, and 4-years after IRS withdrawal from Atacora. This was done to assess how changes in insecticide pressure from indoor residual spraying may have altered the genotypic resistance profile of Anopheles gambiae s.l., Method: Identification of sibling species of An. gambiae s.l. and detection of the L1014F mutation in the kdr gene and G119S mutation in ace-1 genes was done using molecular analysis. Allelic and genotypic frequencies were calculated and compared with each other before and during IRS implementation and 4 years after IRS withdrawal. The Hardy-Weinberg equilibrium and genetic differentiation within and between populations were assessed., Results: Prevalence of the L1014F mutation in all geographic An. gambiae s.l. (An. gambiae s.s., Anopheles. coluzzii, Anopheles. arabiensis, and hybrids of "An. gambiae s.s. and An. coluzzii") populations increased from 69% before IRS to 87% and 90% during and after IRS. The G119S allele frequency during IRS (20%) was significantly higher than before IRS implementation (2%). Four years after IRS withdrawal, allele frequencies returned to similar levels as before IRS (3%). Four years after IRS withdrawal, the populations showed excess heterozygosity at the ace-1 gene and deficit heterozygosity at the kdr gene, whereas both genes had excess heterozygosity before and during IRS (F
IS < 0). No genetic differentiation was observed within the populations., Conclusions: This study shows that the withdrawal of IRS with bendiocarb and pirimiphos-methyl may have slowed down the selection of individual mosquitoes with ace-1 resistance alleles in contrast to populations of An. gambiae s.l. with the L1014F resistance allele of the kdr gene. This may suggest that withdrawing the use of carbamates or organophosphates from IRS or rotating alternative insecticides with different modes of action may slow the development of ace-1 insecticide-resistance mutations. The increase in the prevalence of the L1014F mutation of the kdr gene in the population, despite the cessation of IRS, could be explained by the growing use of pyrethroids and DDT in agriculture and for other domestic use. More observational studies in countries where carbamates or organophosphates are still being used as public health insecticides may provide additional insights into these associations., (© 2024. The Author(s).)- Published
- 2024
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8. Assessing the susceptibility and efficacy of traditional neurotoxic (pyrethroid) and new-generation insecticides (chlorfenapyr, clothianidin, and pyriproxyfen), on wild pyrethroid-resistant populations of Anopheles gambiae from southern Benin.
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Zoungbédji DM, Padonou GG, Konkon AK, Hougbe S, Sagbohan H, Kpanou C, Salako AS, Ossè R, Aïkpon R, Afoukou C, Sidick A, Akinro B, Chitou S, Gnanguénon V, Condo P, Hassani AS, Impoinvil D, and Akogbéto M
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- Animals, Female, Benin, Permethrin, Insecticides pharmacology, Anopheles
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Background: The objective of this study was to determine the susceptibility of wild Anopheles gambiae sensu lato (s.l.) from southern Benin to the new insecticides (chlorfenapyr (CFP), pyriproxyfen (PPF), and clothianidin (CTD)) and assess the efficacy of insecticide-treated bed nets (ITNs) that contain these new products., Methods: Wild An. gambiae from the Benin communes of Allada, Ifangni, Akpro-Missérété, and Porto-Novo were tested for their susceptibility to CFP and PPF using the WHO bottle tests, and pyrethroids (alpha-cypermethrin, deltamethrin, and permethrin) and CTD using WHO tube tests. WHO cone tests were used to evaluate the efficacy of Interceptor
® (which contains alpha-cypermethrin (ACM) only), Interceptor® G2, (CFP + ACM), and Royal Guard® nets (PPF + ACM). The ovaries of blood-fed An. gambiae from Ifangni exposed to a new PPF net were dissected, and egg development status was examined using Christopher's stages to determine the fertility status of the mosquitoes. Using a standardized protocol, the oviposition rate and oviposition inhibition rate were calculated from live blood-fed An. gambiae placed in oviposition chambers after exposure to PPF., Results: In all four mosquito populations, pyrethroid mortality ranged from 5 to 80%, while chlorfenapyr and clothianidin mortality ranged from 98 to 100%. At Ifangni, all mosquitoes exposed to Royal Guard® nets were infertile (100%) while the majority (74.9%) of mosquitoes exposed to Interceptor® nets had fully developed their eggs to Christopher's stage V. The oviposition inhibition rate after exposure of the mosquitoes to the PPF was 99% for the wild population of An. gambiae s.l. and the susceptible laboratory strain, An. gambiae sensu stricto (Kisumu)., Conclusions: The results of this study suggest that pyrethroid-resistant An. gambiae from the selected communes in southern Benin are susceptible to chlorfenapyr, clothianidin, and pyriproxyfen. In addition, based on bioassay results, new and unused Interceptor® G2 and Royal Guard® nets were effective on Ifangni's mosquito populations. Despite the availability of new effective insecticides, continued vigilance is needed in Benin. Therefore, monitoring of resistance to these insecticides will continue to periodically update the Benin national insecticide resistance database and management plan., (© 2023. BioMed Central Ltd., part of Springer Nature.)- Published
- 2023
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9. Insecticide resistance status of Aedes aegypti and Aedes albopictus mosquitoes in southern Benin, West Africa.
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Konkon AK, Padonou GG, Osse R, Salako AS, Zoungbédji DM, Sina H, Sovi A, Tokponnon F, Aïkpon R, Noukpo H, Baba-Moussa L, and Akogbéto MC
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Background: The emergence of insecticide resistance in Aedes mosquitoes could undermine efforts to control arboviruses. The present study aims to assess in some communes of Southern Benin, the susceptibility level of Aedes aegypti (Linnaeus, 1762) and Aedes albopictus (Skuse, 1894) to insecticides commonly used in public health, as well as mechanisms involved., Methods: Females Ae. albopictus and Ae. aegypti collected in Ifangni, Porto-Novo, Avrankou, Adjarra and Kétou from June 2021 to October 2022, were exposed to: deltamethrin 0.05%, permethrin 0.75%, alpha-cypermethrin 0.05%, pirimiphos methyl 0.25% and bendiocarb 0.1%, following the standard WHO susceptibility tube test protocol. In some sites, pre-exposure to the synergist PBO was used to verify if pyrethroid resistance of populations of Aedes was mediated by oxidases., Results: Full susceptibility to deltamethrin and permethrin was observed in all tested populations of Ae. albopictus. However, with alphacypermethrin, a suspected resistance was observed in Adjarra (94.67%), Ifangni (93%) and Porto-Novo (94%), and a resistance in Avrankou (83%). The PBO-alphacypermethrin tests performed, led to a full susceptibility (100%) in all four sites, which confirms the full involvement of oxidases in resistance of all tested populations of Ae. albopictus to alphacypermethrin. At the opposite, Aedes aegypti was either resistant or suspected of being resistant to all tested pyrethroids in all four sites, except in Ifangni where a full susceptibility to alphacypermethrin was observed. The full susceptibility of Ae. aegypti to bendiocarb and pirimiphos-methyl in all communes suggests that these two insecticides can be good candidates for an effective control of pyrethroid-resistant Aedes vector populations. Use of permethrin and deltamethrin could also be considered for controlling populations of Ae. albopictus., Conclusion: Results of the present study will help guide strategy to implement for an effective control of Aedes vector populations in Benin., (© 2023. The Author(s).)
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- 2023
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10. Efficacy of pyriproxyfen-pyrethroid long-lasting insecticidal nets (LLINs) and chlorfenapyr-pyrethroid LLINs compared with pyrethroid-only LLINs for malaria control in Benin: a cluster-randomised, superiority trial.
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Accrombessi M, Cook J, Dangbenon E, Yovogan B, Akpovi H, Sovi A, Adoha C, Assongba L, Sidick A, Akinro B, Ossè R, Tokponnon F, Aïkpon R, Ogouyemi-Hounto A, Padonou GG, Kleinschmidt I, Messenger LA, Rowland M, Ngufor C, Protopopoff N, and Akogbeto MC
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- Animals, Humans, Benin epidemiology, Cross-Sectional Studies, Mosquito Control, Pyrethrins pharmacology, Malaria epidemiology, Malaria prevention & control, Insecticides, Insecticide-Treated Bednets
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Background: New classes of long-lasting insecticidal nets (LLINs) combining mixtures of insecticides with different modes of action could put malaria control back on track after rebounds in transmission across sub-Saharan Africa. We evaluated the relative efficacy of pyriproxyfen-pyrethroid LLINs and chlorfenapyr-pyrethroid LLINs compared with standard LLINs against malaria transmission in an area of high pyrethroid resistance in Benin., Methods: We conducted a cluster-randomised, superiority trial in Zou Department, Benin. Clusters were villages or groups of villages with a minimum of 100 houses. We used restricted randomisation to randomly assign 60 clusters to one of three LLIN groups (1:1:1): to receive nets containing either pyriproxyfen and alpha-cypermethrin (pyrethroid), chlorfenapyr and alpha-cypermethrin, or alpha-cypermethrin only (reference). Households received one LLIN for every two people. The field team, laboratory staff, analyses team, and community members were masked to the group allocation. The primary outcome was malaria case incidence measured over 2 years after net distribution in a cohort of children aged 6 months-10 years, in the intention-to-treat population. This study is ongoing and is registered with ClinicalTrials.gov, NCT03931473., Findings: Between May 23 and June 24, 2019, 53 854 households and 216 289 inhabitants were accounted for in the initial census and included in the study. Between March 19 and 22, 2020, 115 323 LLINs were distributed to 54 030 households in an updated census. A cross-sectional survey showed that study LLIN usage was highest at 9 months after distribution (5532 [76·8%] of 7206 participants), but decreased by 24 months (4032 [60·6%] of 6654). Mean malaria incidence over 2 years after LLIN distribution was 1·03 cases per child-year (95% CI 0·96-1·09) in the pyrethroid-only LLIN reference group, 0·84 cases per child-year (0·78-0·90) in the pyriproxyfen-pyrethroid LLIN group (hazard ratio [HR] 0·86, 95% CI 0·65-1·14; p=0·28), and 0·56 cases per child-year (0·51-0·61) in the chlorfenapyr-pyrethroid LLIN group (HR 0·54, 95% CI 0·42-0·70; p<0·0001)., Interpretation: Over 2 years, chlorfenapyr-pyrethroid LLINs provided greater protection from malaria than pyrethroid-only LLINs in an area with pyrethroid-resistant mosquitoes. Pyriproxyfen-pyrethroid LLINs conferred protection similar to pyrethroid-only LLINs. These findings provide crucial second-trial evidence to enable WHO to make policy recommendations on these new LLIN classes. This study confirms the importance of chlorfenapyr as an LLIN treatment to control malaria in areas with pyrethroid-resistant vectors. However, an arsenal of new active ingredients is required for successful long-term resistance management, and additional innovations, including pyriproxyfen, need to be further investigated for effective vector control strategies., Funding: UNITAID, The Global Fund., Competing Interests: Declaration of interests We declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.)
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- 2023
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11. Digitalized mass distribution campaign of insecticide-treated nets (ITNs) in the particular context of Covid-19 pandemic in Benin: challenges and lessons learned.
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Aïkpon R, Affoukou C, Hounpkatin B, Eclou DD, Cyaka Y, Egwu E, Agbessi N, Tokponnon F, Salifou S, Salami L, and Hounto AO
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- Benin epidemiology, Betacoronavirus isolation & purification, COVID-19, Coronavirus Infections prevention & control, Coronavirus Infections virology, Delivery of Health Care, Education, Family Characteristics, Health Care Surveys, Health Planning Organizations, Humans, Malaria epidemiology, Malaria prevention & control, Pneumonia, Viral prevention & control, Pneumonia, Viral virology, Public Health methods, SARS-CoV-2, Coronavirus Infections epidemiology, Insecticide-Treated Bednets supply & distribution, Pandemics prevention & control, Pneumonia, Viral epidemiology
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Background: In 2020, Benin has implemented a digitalized mass distribution campaign of insecticide-treated nets (ITNs) in the particular context of COVID-19 pandemic. This paper describes the implementation process as well as the challenges and lessons learned from this campaign., Methods: A descriptive design was used for reporting the planning and implementation process of ITNs campaign. Moreover, the changes and adaptations related to COVID-19 pandemic are described., Results: A total of 3,175,773 households were registered corresponding to a total of 14,423,998 persons (13.55% more from projection). Moreover, 94.16% (13,581,637 people) of enumerated population were protected. A total of 7,652,166 ITNs were distributed countrywide., Conclusions: High political commitment, engagement and support add to the financial and technical supports from partners were the essential factors that make 2020 ITNs mass campaign success in Benin despite the particular context of COVID-19 pandemic. It is essential to maintain the prevention activities for malaria and this could substantially reduce the overall impact of the COVID-19 pandemic for the populations at malaria risk.
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- 2020
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12. Lessons learned, challenges and outlooks for decision-making after a decade of experience monitoring the impact of indoor residual spraying in Benin, West Africa.
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Akogbéto MC, Dagnon F, Aïkpon R, Ossé R, Salako AS, Ahogni I, Akinro B, Sominahouin A, Sidick A, Tokponnon F, and Padonou GG
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- Aerosols, Animals, Anopheles classification, Anopheles genetics, Anopheles physiology, Benin epidemiology, Confidence Intervals, Female, Housing, Humans, Incidence, Insecticide-Treated Bednets, Insecticides, Malaria epidemiology, Malaria transmission, Mosquito Control economics, Mosquito Vectors classification, Mosquito Vectors genetics, Mosquito Vectors physiology, Organothiophosphorus Compounds, Phenylcarbamates, Poisson Distribution, Seasons, Insect Bites and Stings prevention & control, Malaria prevention & control, Mosquito Control methods
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Background: Since 2008, Indoor Residual Spraying (IRS) has been performed in Benin in 19 districts, including 4 in southern Benin, 9 in Atacora, and 8 in Atacora, Alibori and Donga in northern Benin. However, Benin still struggles with questions about IRS cost-benefit and epidemiological impact. Lessons learned and challenges from 10 years of IRS in Benin to be shared with the stakeholders involved in vector control implementation for decision-making., Methods: Entomological parameters have been assessed entomological parameters in IRS communes since 2008. In all IRS intervention communes, decreases in human biting rate (HBR) of Anopheles gambiae, blood feeding inhibition and entomological inoculation rate (EIR) as compared to control district have been measured., Results: EIR was reduced by 80-90%, which is encouraging, but should be observed with caution because: (i) the reduction may be insufficient to decrease epidemiological indicators given that the residual EIR in IRS districts is still higher than it is in some regions of stable malaria; (ii) the reduction in EIR is based on comparisons with control communes, but it is difficult to select control areas with the same environmental characteristics as intervention areas; (iii) despite the reduction, half of all mosquitoes that entered IRS-treated houses succeeded in taking human blood meals. Further, there are behaviours among Benin's population that limit IRS efficacy, including recent data showing that > 90% of people are not protected by IRS between 7 and 10 p.m. This is due to the fact that they remain outdoors and that most people are not protected from mosquito bites after 10 p.m. because they either sleep outdoors without IRS protection or indoors without an ITN. Moreover, people have large amounts of clothing hanging on walls where mosquitoes can rest instead of IRS-treated walls. Finally, other components are important to consider in implementing IRS among which: (i) Vector resistance management strategies are sometimes poorly understood; this is actually different from the need to replace one insecticide with another after the emergence of resistance; (ii) African countries should prepare to finance IRS themselves., Conclusion: To curtail residual malaria transmission, additional interventions able to target vectors escaping IRS should be prioritized.
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- 2020
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13. 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.
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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, and Akogbeto MC
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- Animals, Anopheles parasitology, Anopheles physiology, Benin, Female, Humans, Malaria parasitology, Mosquito Control instrumentation, Mosquito Vectors parasitology, Mosquito Vectors physiology, Plasmodium genetics, Plasmodium isolation & purification, Plasmodium physiology, Anopheles drug effects, Insecticides pharmacology, Malaria transmission, Mosquito Control methods, Mosquito Vectors drug effects, Organothiophosphorus Compounds pharmacology
- 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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- 2019
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14. Population Dynamics of Anopheles gambiae s.l. and Culex quinquefasciatus in Rural and Urban Settings Before an Indoor Residual Spraying Campaign in Northern Benin.
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Salako AS, Ossè R, Padonou GG, Dagnon F, Aïkpon R, Kpanou C, Sagbohan H, Sovi A, Sèzonlin M, and Akogbeto MC
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- Animals, Benin, Housing, Humans, Insecticides administration & dosage, Mosquito Control, Mosquito Vectors, Population Dynamics, Animal Distribution, Anopheles physiology, Culex physiology, Insecticides pharmacology, Pyrethrins administration & dosage
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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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- 2019
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15. Involvement of Anopheles nili in Plasmodium falciparum transmission in North Benin.
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Ossè RA, Tokponnon F, Padonou GG, Sidick A, Aïkpon R, Fassinou A, Koukpo CZ, Sèwadé W, Akinro B, Sovi A, Aïssi M, and Akogbéto MC
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- Animals, Benin epidemiology, Bites and Stings, Cross-Sectional Studies, Enzyme-Linked Immunosorbent Assay, Feeding Behavior, Humans, Malaria, Falciparum epidemiology, Mosquito Vectors parasitology, Plasmodium falciparum, Polymerase Chain Reaction, Seasons, Sporozoites, Anopheles classification, Anopheles parasitology, Malaria, Falciparum transmission, Mosquito Vectors classification
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Background: Several studies carried out in Benin have shown the involvement of Anopheles gambiae sensu lato (s.l.), the Anopheles funestus group in malaria transmission, but none of them reported the contribution of the Anopheles nili group to the transmission of this disease. The current study investigated the question through an entomological cross-sectional survey performed in Northern Benin., Methods: Mosquito samplings were performed in September and October 2017 in 4 villages located in two districts: Bambaba and Wodara (Kérou district) and, Péhunco 2 and Béké (Péhunco district). The collections were carried out indoors and outdoors using human landing catches (HLC) to assess the human biting rate (HBR) and pyrethrum spray catches (PSC) to evaluate the blood feeding rate and the blood meal origin using the ELISA test. All collected mosquitoes were morphologically identified and, the polymerase chain reaction (PCR) technique was used for molecular identification of sibling species of An. gambiae s.l., An. funestus group and An. nili group sporozoite index (SI) was also assessed by the ELISA test., Results: Overall, An. gambiae s.l., An. funestus group and An. nili group were the three vectors found in the study area. A significantly higher human biting rate (HBR) was recorded in An. nili group (5 bites/human/night) compared to An. funestus group (0.656 bites/human/night) in the Kérou district (p < 0.0001). Anopheles gambiae s.l. displayed the highest HBR (26.19 bites/human/night) in the same district. The entomological inoculation rate (EIR) was 1.875 infected bites/human/month in An. nili group against 13.05 infected bites/human/month in An. gambiae s.l. and 0.938 infected bites/human/month in An. funestus group in Kérou. In Péhunco, the EIR was 1.02 infected bites/human/month in An. gambiae s.l. PCR results showed that An. nili sensu stricto (s.s.) and An. funestus s.s. were the only species of the An. nili and An. funestus groups, respectively. The anthropophagic character of An. gambiae s.l. was also highlighted., Conclusion: This study provides useful information on the contribution of An. nili group as secondary vector to malaria transmission in northern Benin. Broader studies must also be carried out in a larger study area to assess the involvement of other Anopheles species to malaria transmission. This will aid to better plan malaria vector control interventions.
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- 2019
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16. 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.
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Salako AS, Ahogni I, Aïkpon R, Sidick A, Dagnon F, Sovi A, Sominahouin AA, Agossa F, Iyikirenga L, and Akogbeto MC
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- Animals, Anopheles classification, Benin, Esterases analysis, Female, Genes, Insect genetics, Glutathione Transferase analysis, Insect Proteins genetics, Larva classification, Larva drug effects, Larva genetics, Mixed Function Oxygenases analysis, Mutation, Organothiophosphorus Compounds pharmacology, Pesticide Synergists pharmacology, Phenylcarbamates pharmacology, Piperonyl Butoxide pharmacology, Pyrethrins pharmacology, Anopheles drug effects, Anopheles genetics, Insecticide Resistance genetics, Insecticides pharmacology, Mosquito Control methods
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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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- 2018
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17. Blood feeding behaviour comparison and contribution of Anopheles coluzzii and Anopheles gambiae, two sibling species living in sympatry, to malaria transmission in Alibori and Donga region, northern Benin, West Africa.
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Akogbéto MC, Salako AS, Dagnon F, Aïkpon R, Kouletio M, Sovi A, and Sezonlin M
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- Adult, Animals, Benin, Female, Humans, Insect Proteins genetics, Insecticide Resistance, Mutation, Anopheles physiology, Disease Transmission, Infectious, Feeding Behavior, Malaria transmission, Mosquito Vectors physiology, Sympatry
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Background: The main goal of this study was to assess the blood feeding behaviour and the contribution Anopheles coluzzii and Anopheles gambiae, 2 sibling species of An. gambiae sensu stricto. present and living in sympatry in 2 regions of northern Benin targeted for indoor residual spraying (IRS)., Methods: The study was carried out in 6 districts of 2 regions of Benin (Alibori and Donga). Human landing catches (HLC) performed inside and outside of the households and pyrethrum spray captures (PSC) carried out in bedrooms were used to sample vector populations (An. gambiae and An. coluzzii). Collected mosquitoes were analysed to estimate the human biting rate indoors and outdoors, the circumsporozoite antigen positivity, and the anthropophagic index using ELISA methodology. Polymerase chain reaction was used to estimate the frequency of the knockdown resistance (kdr) L1014F and the ace-1 mutations, 2 markers associated respectively with pyrethroids and carbamate/organophosphate insecticide resistance., Results: A higher blood feeding rate was observed in An. gambiae compared to An. coluzzii as well as, a non-pronounced outdoor biting behavior in both species. The latter showed similar anthropophagic and sporozoite rates. However the analysis indicates a seasonal difference in the contribution of each species to malaria transmission associated with shifts in resting behaviour. Anopheles coluzzii females accounted for most of the detected infections: 86% in Alibori and 79% in Donga, during the dry season versus 14.4% and 21.2%, respectively for An. gambiae during the same period. This relationship was reversed in Donga during the rainy season (66% for An. gambiae against 34% for An. coluzzii). Results also indicated lower frequencies of kdr L1014F and ace-1 in An. coluzzii versus An. gambiae., Conclusion: Despite similarity in some parameters related to malaria transmission in both surveyed species, An. coluzzii is potentially a more important malaria vector because of high density in the region. It is also characterized by lower frequencies of the ace-1 mutation than is An. gambiae. The ongoing use of pirimiphos methyl (organophosphate) for IRS should continue to show a good impact in Alibori and Donga because of the very low level of the ace-1 mutation in both species.
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- 2018
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18. Malaria vectors resistance to insecticides in Benin: current trends and mechanisms involved.
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Gnanguenon V, Agossa FR, Badirou K, Govoetchan R, Anagonou R, Oke-Agbo F, Azondekon R, AgbanrinYoussouf R, Attolou R, Tokponnon FT, Aïkpon R, Ossè R, and Akogbeto MC
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- Animals, Benin, Biological Assay, Geography, Larva drug effects, Survival Analysis, Anopheles drug effects, Insect Vectors drug effects, Insecticide Resistance, Insecticides pharmacology
- Abstract
Background: Insecticides are widely used to control malaria vectors and have significantly contributed to the reduction of malaria-caused mortality. In addition, the same classes of insecticides were widely introduced and used in agriculture in Benin since 1980s. These factors probably contributed to the selection of insecticide resistance in malaria vector populations reported in several localities in Benin. This insecticide resistance represents a threat to vector control tool and should be monitored. The present study reveals observed insecticide resistance trends in Benin to help for a better management of insecticide resistance., Methods: Mosquito larvae were collected in eight sites and reared in laboratory. Bioassays were conducted on the adult mosquitoes upon the four types of insecticide currently used in public health in Benin. Knock-down resistance, insensitive acetylcholinesterase-1 resistance, and metabolic resistance analysis were performed in the mosquito populations based on molecular and biochemical analysis. The data were mapped using Geographical Information Systems (GIS) with Arcgis software., Results: Mortalities observed with Deltamethrin (pyrethroid class) were less than 90% in 5 locations, between 90-97% in 2 locations, and over 98% in one location. Bendiocarb (carbamate class) showed mortalities ranged 90-97% in 2 locations and were over 98% in the others locations. A complete susceptibility to Pirimiphos methyl and Fenitrothion (organophosphate class) was observed in all locations with 98-100% mortalities. Knock-down resistance frequencies were high (0.78-0.96) and similar between Anopheles coluzzii, Anopheles gambiae, Anopheles arabiensis, and Anopheles melas. Insensitive acetylcholinesterase-1 was rare (0.002-0.1) and only detected in Anopheles gambiae in concomitance with Knock-down resistance mutation. The maps showed a large distribution of Deltamethrin resistance, Knock-down mutation and metabolic resistance throughout the country, a suspected resistance to Bendiocarb and detection of insensitive acetylcholinesterase-1 from northern Benin, and a wide distribution of susceptible vectors to Pirimiphos methyl and Fenitrothion., Conclusion: This study showed a widespread resistance of malaria vectors to pyrethroid previously located in southern Benin, an early emergence of carbamates resistance from northern Benin and a full susceptibility to organophosphates. Several resistance mechanisms were detected in vectors with a potential cross resistance to pyrethroids through Knock-down and metabolic resistance mechanisms.
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- 2015
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19. Evidence of multiple mechanisms providing carbamate and organophosphate resistance in field An. gambiae population from Atacora in Benin.
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Aïkpon R, Sèzonlin M, Ossè R, and Akogbéto M
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- Animals, Benin, Carbamates chemistry, Female, Insecticide Resistance, Insecticides chemistry, Organophosphates chemistry, Anopheles drug effects, Carbamates pharmacology, Insecticides pharmacology, Organophosphates pharmacology
- Abstract
Background: Insecticide resistance in Anopheles gambiae s.l is a major concern to malaria vector control programmes. In West Africa, resistance is mainly due to target-site insensitivity arising from a single point mutation. Metabolic-based resistance mechanisms have also been implicated and are currently being investigated in west Africa. The aim of this study is to better understand the origins of carbamate and organophosphate resistance in An. gambiae population from Atacora, Benin in West Africa., Methods: Anopheles mosquitoes were reared from larvae collected in two districts (Kouandé and Tanguiéta) of the Atacora department. Mosquitoes were then exposed to WHO impregnated papers. Four impregnated papers were used: carbamates (0.1% bendiocarb, 0.1% propoxur) and organophosphates (0.25% pirimiphos methyl, 1% fenitrothion). PCR assays were run to determine the members of the An. gambiae complex, as well as phenotypes for insensitive acetylcholinesterase (AChE1). Biochemical assays were also carried out to detect any increase in the activity of enzyme typically involved in insecticide metabolism (oxidase, esterase and glutathion-S-transferase)., Results: 769 female of An. gambiae mosquitoes from Kouandé and Tanguiéta were exposed to bendiocarb, propoxur, pirimiphos methyl and fenitrothion. Bioassays showed resistance with low mortality to bendiocarb (78.57% to 80.17%), propoxur (77.21% to 89.77%), and fenitrothion (89.74% to 92.02%). On the other hand, the same populations of An. gambiae from Kouandé and Tanguiéta showed high susceptibility to pirimiphos methyl with recorded mortality of 99.02% and 100% respectively. The low rate of ace-1R allele frequency (3.75% among survivors and 0.48% among dead) added to the high proportion of homozygous susceptible specimens which survived the WHO bioassays (8/28), suggest that the ace-1 mutation could not entirely explain Anopheles gambiae resistance to carbamate and organophosphate. Biochemical assays suggest that resistance in this population is mediated by metabolic resistance with elevated level of GST, MFO and NSE compared to a susceptible strain An. gambiae Kisumu., Conclusions: Anopheles gambiae populations resistance from Atacora is multifactorial and includes target-site mutation and metabolic mechanism. The co-implication of both resistance mechanisms in An. gambiae s.l may be a serious obstacle for the future success of malaria control operations based on LLINs and IRS.
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- 2014
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20. Study of the efficacy of a Wheaton coated bottle with permethrin and deltamethrin in laboratory conditions and a WHO impregnated paper with bendiocarb in field conditions.
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Aïzoun N, Azondekon R, Aïkpon R, Gnanguenon V, Osse R, Asidi A, and Akogbéto M
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Objective: To determine the efficacy of WHO impregnated paper and CDC coated bottle based on number of storage days and number of times of consecutive use, in the assessment of insecticide vector susceptibility tests in laboratory and field conditions., Methods: Larvae and pupae of Anopheles gambiae s.l. mosquitoes were collected from the breeding sites in Seme-Kpodji and Cotonou districts in Southern Benin in April 2013 during the first rainy season. Anopheles gambiae s.l. mosquitoes were also collected from the breeding sites in Parakou district in Northern Benin in May 2013 at the beginning of the rainy season. Susceptibility tests were done using impregnated paper with bendiocarb (0.1%) following WHO protocol and stock solutions of permethrin (21.5 µg per bottle) and deltamethrin (12.5 µg per bottle) following CDC protocol on unfed female mosquitoes aged 2-5 days old. These bioassays were repeated a certain number of times. The temperature and relative humidity were monitored and recorded during the susceptibility tests., Results: This study showed that a WHO impregnated paper with bendiocarb could be used four times during four consecutive days in field conditions. Regarding a Wheaton coated bottle with permethrin or deltamethrin, they could be used at least three times during four consecutive days in laboratory conditions., Conclusions: The day storage and the number of times that a WHO impregnated paper and a CDC coated bottle maintained their efficacy are useful in the assessment of insecticide vectors susceptibility tests.
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- 2014
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21. Good performances but short lasting efficacy of Actellic 50 EC Indoor Residual Spraying (IRS) on malaria transmission in Benin, West Africa.
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Aïkpon R, Sèzonlin M, Tokponon F, Okè M, Oussou O, Oké-Agbo F, Beach R, and Akogbéto M
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- Animals, Benin epidemiology, Biological Assay, Housing, Humans, Insect Vectors, Insecticides administration & dosage, Malaria epidemiology, Malaria prevention & control, Organothiophosphorus Compounds administration & dosage, Anopheles drug effects, Insecticides pharmacology, Malaria transmission, Mosquito Control methods, Organothiophosphorus Compounds pharmacology
- 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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- 2014
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22. Comparative susceptibility to permethrin of two Anopheles gambiae s.l. populations from Southern Benin, regarding mosquito sex, physiological status, and mosquito age.
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Aïzoun N, Aïkpon R, Azondekon R, Asidi A, and Akogbéto M
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Objective: To investigate what kind of mosquito sample is necessary for the determination of insecticide susceptibility in malaria vectors., Methods: Larvae and pupae of Anopheles gambiae s.l. (An. gambiae) mosquitoes were collected from the breeding sites in Littoral and Oueme departments. The Centers for Disease Control and Prevention (CDC) susceptibility tests were conducted on unfed male and female mosquitoes aged 2-5 days old. CDC susceptibility tests were also conducted on unfed, blood fed and gravid female mosquitoes aged 2-5 days old. These susceptibility tests were also conducted on unfed and blood fed female mosquitoes aged 2-5 days old and 20 days old. CDC biochemical assay using synergist was also carried out to detect any increase in the activity of enzyme typically involved in insecticide metabolism., Results: Female An. gambiae Ladji and Sekandji populations were more susceptible than the males when they were unfed and aged 2-5 days old. The mortality rates of blood fed female An. gambiae Ladji and Sekandji populations aged 2-5 days old were lower than those obtained when females were unfed. In addition, the mortality rates of gravid female An. gambiae Ladji and Sekandji populations aged 2-5 days old were lower than those obtained when they were unfed. The mortality rate obtained when female An. gambiae Sekandji populations were unfed and aged 20 days old was higher than the one obtained when these populations were unfed and aged 2-5 days old. The results obtained after effects of synergist penicillin in beeswax on F1 progeny of An. gambiae Ladji populations resistant to permethrin showed that mono-oxygenases were involved in permethrin resistant F1 progeny from Ladji., Conclusions: The resistance is a hereditary and dynamic phenomenon which can be due to metabolic mechanisms like overproduction of detoxifying enzymes activity. Many factors influence vector susceptibility to insecticide. Among these factors, there are mosquito sex, mosquito age, its physiological status. Therefore, it is useful to respect the World Health Organization criteria in the assessment of insecticide susceptibility tests in malaria vectors. Otherwise, susceptibility testing is conducted using unfed female mosquitoes aged 3-5 days old. Tests should also be carried out at (25±2) °C and (80±10)% relative humidity.
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- 2014
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23. Evidence of increasing L1014F kdr mutation frequency in Anopheles gambiae s.l. pyrethroid resistant following a nationwide distribution of LLINs by the Beninese National Malaria Control Programme.
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Aïzoun N, Aïkpon R, and Akogbéto M
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Objective: To determine the susceptibility status to pyrethroid in Anopheles gambiae s.l. (An. gambiae), the distribution of kdr "Leu-Phe" mutation in malaria vectors in Benin and to compare the current frequency of kdr "Leu-Phe" mutation to the previous frequency after long-lasting insecticide treated nets implementation., Methods: Larvae and pupae of An. gambiae s.l. mosquitoes were collected from the breeding sites in Littoral, Zou, Borgou and Alibori provinces. CDC susceptibility tests were conducted on unfed females mosquitoes aged 2-5 d old. An. gambiae mosquitoes were identified to species using PCR techniques. Molecular assays were also carried out to identify kdr mutations in individual mosquitoes., Results: The results showed that An. gambiae Malanville and Suru-lere populations were resistant to deltamethrin. Regarding An. gambiae Parakou and Bohicon populations, they were resistant to permethrin. PCR revealed 100% of mosquitoes tested were An. gambiae s.s. The L1014F kdr mutation was found in An. gambiae s.s. Malanville and Parakou at various allelic frequencies. The increase of kdr allelic frequency was positively correlated with CDC bioassays data., Conclusions: : Pyrethroid resistance is widespread in malaria vector in Benin and kdr mutation is the main resistance mechanism involved. More attention may be paid for the future success of malaria control programmes based on LLINs with pyrethroids in the country.
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- 2014
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24. Efficacy of various insecticides recommended for indoor residual spraying: pirimiphos methyl, potential alternative to bendiocarb for pyrethroid resistance management in Benin, West Africa.
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Agossa FR, Aïkpon R, Azondékon R, Govoetchan R, Padonnou GG, Oussou O, Oké-Agbo F, and Akogbéto MC
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- Animals, Benin, Housing, Anopheles drug effects, Insect Control methods, Insecticide Resistance drug effects, Insecticides, Malaria prevention & control, Organothiophosphorus Compounds, Phenylcarbamates
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Background: Using the same insecticide for multiple successive indoor residual spraying (IRS) cycles is not recommended; instead, the National Malaria Control Program (NMCP) has decided to select another insecticide (insecticide B) in addition to bendiocarb for indoor residual spraying., Methods: An experimental hut trial comparing the effectiveness of three classes of insecticides (one carbamate [bendiocarb], two organophosphates [fenitrothion and pirimiphos methyl] and one pyrethroid [lambdacyalothrin]) was conducted in Malanville, northern Benin, against wild free entered resistant Anopheles gambiae s.l. population to pyrethroids., Results: Fenitrothion and pirimiphos methyl yielded the highest rate of deterrence. Their mean rates were respectively 46.6% and 35.4%. Regarding blood feeding inhibition, only fenitrothion has induced a significant inhibition rate (25.4% as mean rate). As regards the exophily rates, only lambdacyhalothrin has induced the highest rate (39.7%). Pirimiphos methyl showed the highest mortality rate and also induced a mortality rate of at least 80% in blood fed An. gambiae population after 24 h observation time. Furthermore, the huts treated with pirimiphos methyl showed the highest residual effect, followed by lambdacyhalothrin., Conclusion: Benin NMCP has selected pirimiphos methyl as insecticide B to alternate or combine to bendiocarb (carbamate) because of the adverse effects of fenitrothion on the sleepers and its short residual effect on walls.
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- 2014
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25. Impact of land-use on malaria transmission in the Plateau region, southeastern Benin.
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Sovi A, Govoétchan R, Tokponnon F, Hounkonnou H, Aïkpon R, Agossa F, Gnanguenon V, Salako AS, Agossou C, Ossè R, Okè M, Gbénou D, Massougbodji A, and Akogbéto M
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- Animals, Anopheles drug effects, Benin epidemiology, Female, Human Activities, Humans, Insecticide Resistance, Insecticides pharmacology, Larva drug effects, Larva physiology, Malaria epidemiology, Nitriles pharmacology, Permethrin pharmacology, Pyrethrins pharmacology, Rural Population, Anopheles physiology, Malaria transmission
- Abstract
Background: The goal of the study is to investigate if local agricultural practices have an impact on malaria transmission in four villages located in the same geographical area within a radius of 15 kilometers. Among the villages, one (Itassoumba) is characterized by the presence of a large market garden and fishpond basins, the three others (Itakpako, Djohounkollé and Ko-koumolou) are characterized by traditional food-producing agriculture., Methods: Malaria transmission was evaluated using human-landing catches, both indoors and outdoors, two nights per month for 12 months. Field collected females An. gambiae s.l. were exposed for 1 hour to 0.75% permethrin and 0.05% deltamethrin using WHO insecticide susceptibility test kits and procedures. The presence of the kdr mutation was analyzed by PCR., Results: Anopheles gambiae s.s form M (93.65%), was identified as the main malaria vector. Its susceptibility level to pyrethroids was the same (p > 0.05) in all villages. kdr mutation frequencies are 81.08 in Itakpako, 85 in Itassoumba, 79.73 in Djohounkollé and 86.84 in Ko-Koumolou (p = 0.63). The entomological inoculation rate ranged from 9.62 to 21.65 infected bites of An. gambiae per human per year in Djohounkollé, Itakpako and Ko-Koumolou against 1159.62 in Itassoumba (p < 0.0001)., Conclusion: The level of resistance of An. gambiae to pyrethroids was the same in the four villages. The heterogeneous character of malaria epidemiology was confirmed. The creation of fishponds basins and the development of market-gardening activities increased drastically the malaria transmission in Itassoumba.
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- 2013
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26. Status of organophosphate and carbamate resistance in Anopheles gambiae sensu lato from the south and north Benin, West Africa.
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Aïzoun N, Aïkpon R, Gnanguenon V, Oussou O, Agossa F, Padonou G, and Akogbéto M
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- Animals, Anopheles classification, Benin, Female, Anopheles drug effects, Fenitrothion pharmacology, Insecticide Resistance, Insecticides pharmacology, Phenylcarbamates pharmacology
- Abstract
Background: With the rapid spread of pyrethroid resistance in the main malaria vectors from Benin and the various resistance mechanisms involved (metabolic resistance and knock-down resistance (kdr), it is important to foresee effective resistance management strategies. Thus, the knowledge of the insensitive acetylcholinesterase (ace-1R) effects on phenotypes of An. gambiae will help us to strengthen basic and operational research on the development of strategies that will use organophosphates or carbamates as alternatives against pyrethroids-resistant malaria vectors in the field., Methods: Larvae and pupae of Anopheles gambiae s.l. mosquitoes were collected from the breeding sites in Ouemé , Atacora, and Alibori departments. CDC susceptibility tests were conducted on unfed female mosquitoes aged 2-5 days old. CDC bioassays were performed with stock solutions of fenitrothion (50 μg per bottle) and bendiocarb (12.5 μg per bottle). PCR techniques were used to detect species and Ace-1 mutations., Results: Anopheles gambiae Seme and Kandi populations were susceptible to fenitrothion whereas Anopheles gambiae Tanguieta and Malanville populations were resistant. An. gambiae populations from Seme, Kandi and Malanville were fully susceptible to bendiocarb whereas those from Tanguieta have developed a strong resistance to the same insecticide. A slight decrease in mortality rate was observed with 97.91% in populations of mosquitoes from Malanville. PCR revealed that all specimens tested were Anopheles gambiae s.s.., Conclusion: This study demonstrated the need to monitor organophosphate (OPs) and Carbamates resistance among populations of the An. gambiae s.l. in Benin, to determine its spread and anticipate vector control failure where these insecticides are used. However, further studies are needed to understand the current distribution of the Ace-1R mutation in other localities in the south-north transect Benin.
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- 2013
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27. Evidence of man-vector contact in torn long-lasting insecticide-treated nets.
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Gnanguenon V, Azondekon R, Oke-Agbo F, Sovi A, Ossè R, Padonou G, Aïkpon R, and Akogbeto MC
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- Animals, Case-Control Studies, Humans, Insecticide Resistance, Insecticides pharmacology, Anopheles classification, Anopheles drug effects, Insect Bites and Stings prevention & control, Insect Vectors drug effects, Insecticide-Treated Bednets standards
- 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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- 2013
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28. Mixed-function oxidases and esterases associated with permethrin, deltamethrin and bendiocarb resistance in Anopheles gambiae s.l. in the south-north transect Benin, West Africa.
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Aïzoun N, Aïkpon R, Padonou GG, Oussou O, Oké-Agbo F, Gnanguenon V, Ossè R, and Akogbéto M
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- Animals, Anopheles drug effects, Biological Assay, Drug Synergism, Female, Humans, Insect Proteins metabolism, Insecticide Resistance, Larva, Nitriles pharmacology, Permethrin pharmacology, Phenotype, Phenylcarbamates pharmacology, Pyrethrins pharmacology, Anopheles enzymology, Esterases metabolism, Insecticides pharmacology, Malaria prevention & control, Mixed Function Oxygenases metabolism, Mosquito Control
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Background: Insecticide resistance monitoring is essential to help national programmers to implement more effective and sustainable malaria control strategies in endemic countries. The current study aimed at an exploring the involvement of detoxifying enzymes in the insecticide phenotype resistance in Anopheles gambiae s.l.from Benin, in order to guide future malaria vector control interventions., Methods: Larvae and pupae of Anopheles gambiae s.l. mosquitoes were collected from the breeding sites in Oueme, Atacora and Alibori provinces. CDC susceptibility tests were conducted on unfed female mosquitoes aged 2-5 days old. CDC bioassays were performed with stock solutions of permethrin (21.5 μg per bottle), deltamethrin (12.5 μg per bottle) and bendiocarb (12.5 μg per bottle). CDC biochemical assays using synergists were also conducted to assess the metabolic resistance., Results: The susceptibility of Anopheles gambiae Agbalilame and Kandi populations to permethrin and deltamethrin respectively, increased significantly when synergized by PBO, suggesting an implication of mono-oxygenases in resistance of Anopheles gambiae s.l. to pyrethroid. Esterases may play a role in bendiocarb resistance in Anopheles gambiae Tanguieta., Conclusion: Synergists partially restored susceptibility to pyrethroid and carbamate insecticides and might help mitigate the impact of vector resistance in Anopheles gambiae Agbalilame, Kandi and Tanguieta populations. However, additional vector control tools are needed to further impact on malaria transmission in such settings.This will improve the implementation and management of future control programs against this important malaria vector in Benin and in Africa in general.
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- 2013
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29. Bendiocarb resistance in Anopheles gambiae s.l. populations from Atacora department in Benin, West Africa: a threat for malaria vector control.
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Aïkpon R, Agossa F, Ossè R, Oussou O, Aïzoun N, Oké-Agbo F, and Akogbéto M
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- Acetylcholinesterase genetics, Animals, Anopheles classification, Anopheles genetics, Benin, Biological Assay, Female, Genotype, Humans, Malaria prevention & control, Malaria transmission, Mosquito Control methods, Mutation, Polymerase Chain Reaction, Survival Analysis, Anopheles drug effects, Insect Vectors drug effects, Insecticide Resistance, Insecticides pharmacology, Phenylcarbamates pharmacology
- 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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- 2013
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30. A shift from indoor residual spraying (IRS) with bendiocarb to long-lasting insecticidal (mosquito) nets (LLINs) associated with changes in malaria transmission indicators in pyrethroid resistance areas in Benin.
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Ossè RA, Aïkpon R, Gbédjissi GL, Gnanguenon V, Sèzonlin M, Govoétchan R, Sovi A, Oussou O, Oké-Agbo F, and Akogbéto M
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- Animals, Benin, Female, Geography, Humans, Insecticide Resistance, Insecticide-Treated Bednets, Malaria transmission, Mosquito Control, Phenylcarbamates pharmacology, Pyrethrins pharmacology, Anopheles drug effects, Insect Bites and Stings prevention & control, Insect Vectors drug effects, Insecticides pharmacology, Malaria prevention & control, Plasmodium falciparum drug effects
- Abstract
Background: Indoor residual spraying (IRS) was implemented in the department of Ouémé-Plateau, southern Benin, in 2008 and withdrawn in 2011, when long lasting insecticidal nets (LLINs) were distributed to the communities that were previously targeted by IRS. Did the LLIN strategy provide a better level of protection against malaria transmission than IRS?, Methods: Entomological surveillance was carried out to assess indicators of transmission risk during the last year of IRS and the first year after the LLIN intervention was put in place (2010-2011). Mosquito biting density was sampled by human landing collection (HLC). Females of Anopheles gambiae s.l. were dissected to estimate the parity rates and the blood meal index. A subsample of the An. gambiae s.l. collection was tested for presence of Plasmodium falciparum sporozoites. In addition, window exit traps and pyrethrum spray catches were performed to assess exophagic behavior of Anopheles vectors., Results: There were significant increases in all the indicators following withdrawal of IRS. Vector biting density (p<0.001) and longevity (OR=3.81[3.01-4.82] 95% CI; p<0.001) of the An. gambiae s.l. increased significantly; so too did the blood meal index (OR=1.48 [1.1-1.99] 95% CI; p<0.001). Entomological inoculation rate, after IRS withdrawal at one surveillance site, Adjohoun, rose two fold (9.0 infected bites/person/9 months (Apr-Dec 2011) versus 3.66 infective bites/person during the 9 months preceding IRS (Apr-Dec 2010). A second site, Missérété, experienced a six-fold increase after IRS cessation (15.1 infective bites/person/9 months versus 2.41 during IRS). Exophily after IRS cessation decreased significantly in all areas (p<0.001) suggesting that mosquitoes were more likely to rest in houses with LLINs, than in houses subjected to IRS., Conclusion: LLINs did not impact on indicators of transmission to the same levels as did IRS after IRS withdrawal.
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- 2013
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