Last data update: Jan 27, 2025. (Total: 48650 publications since 2009)
Records 1-3 (of 3 Records) |
Query Trace: Yepassis-Zembrou P[original query] |
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Level of involvement of four selected cytochrome P450s (CYPs) in pyrethroid-resistant Anopheles gambiae (s.s.) and Anopheles coluzzii across Côte d'Ivoire
Chabi J , Edi CVA , Kouassi BL , Gbalegba CNG , Kouassi AE , Kouame JKI , Kadio YKA , Yokoly FN , Golou LB , Gouaméné J , Assamoi JB , Tia E , Yapo RM , Konan LY , N'Tamon RN , Koffi AA , Tanoh AM , Ging-Cissé N , Zinzindohoué P , Kouadio B , Yepassis-Zembrou PL , Irish SR , Flatley C , Kirby M . Curr Res Parasitol Vector-Borne Dis 2024 6 In Côte d'Ivoire, there is a high intensity of pyrethroid resistance in malaria vectors which may threaten successful vector control. Molecular studies of the target site mutation in the voltage-gated sodium channel (VGSC) 1014F show that the gene frequencies of these mutations are high, widely spread across Côte d'Ivoire, and even fixed in some areas. To further characterize insecticide resistance in Côte d'Ivoire beyond target site mutations, the metabolic resistance mechanism was explored. Overexpression of the metabolic enzyme cytochrome CYP6M2, CYP6P3, CYP6P4, and CYP6P5 was investigated in Anopheles gambiae (s.s.) and An. coluzzii collected from 30 insecticide resistance monitoring sites across the country in 2021 and 2022. Quantitative real-time polymerase chain reaction (qRT-PCR) assay was carried out using RNA-later preserved 60 surviving mosquitoes from each site after phenotypic susceptibility tests. Additionally, a subsample of about 100 mosquitoes from each site was identified to species by PCR, and the frequency of the VGSC 1014F and 1014S was determined. All four CYPs were found to be overexpressed in Côte d'Ivoire with at least one CYP statistically significantly overexpressed in 27 of the 30 sites investigated compared to the susceptible An. gambiae (s.s.) Kisumu (P < 0.005). CYP6M2 was overexpressed in 89% of sites and was the sole overexpressed gene in 10 sites, while the overexpression of CYP6P3 was found in only 10 sites. CYP6P4 and CYP6P5 were overexpressed in 16 and 13 sites, respectively. Furthermore, seven sites (Adzopé, Bongouanou, Daloa, Gagnoa, Guiglo Jacqueville, and Sassandra) had overexpression of all four CYPs. Overall, An. coluzzii showed higher overexpression of CYPs than An. gambiae (s.s.). This study highlights the involvement of selected CYPs in insecticide resistance where target site mutation genes are already present, suggesting that insecticide resistance is complex and multifaceted at a molecular level. Where feasible, it may be helpful to include metabolic resistance surveillance to further characterize insecticide resistance. © 2024 The Authors |
Reduction of malaria case incidence following the introduction of clothianidin-based indoor residual spraying in previously unsprayed districts: an observational analysis using health facility register data from Côte d'Ivoire, 2018-2022
Hilton ER , Gning-Cisse N , Assi A , Eyakou M , Koffi J , Gnakou B , Kouassi B , Flatley C , Chabi J , Gbalegba C , Alex Aimain S , Yah Kokrasset C , Antoine Tanoh M , N'Gotta S , Yao O , Egou Assi H , Konan P , Davis K , Constant E , Belemvire A , Yepassis-Zembrou P , Zinzindohoue P , Kouadio B , Burnett S . BMJ Glob Health 2024 9 (3) BACKGROUND: Indoor residual spraying (IRS) using neonicotinoid-based insecticides (clothianidin and combined clothianidin with deltamethrin) was deployed in two previously unsprayed districts of Côte d'Ivoire in 2020 and 2021 to complement standard pyrethroid insecticide-treated nets. This retrospective observational study uses health facility register data to assess the impact of IRS on clinically reported malaria case incidence. METHODS: Health facility data were abstracted from consultation registers for the period September 2018 to April 2022 in two IRS districts and two control districts that did not receive IRS. Malaria cases reported by community health workers (CHWs) were obtained from district reports and District Health Information Systems 2. Facilities missing complete data were excluded. Controlled interrupted time series models were used to estimate the effect of IRS on monthly all-ages population-adjusted confirmed malaria cases and cases averted by IRS. Models controlled for transmission season, precipitation, vegetation, temperature, proportion of cases reported by CHWs, proportion of tested out of suspected cases and non-malaria outpatient visits. RESULTS: An estimated 10 988 (95% CI 5694 to 18 188) malaria cases were averted in IRS districts the year following the 2020 IRS campaign, representing a 15.9% reduction compared with if IRS had not been deployed. Case incidence in IRS districts dropped by 27.7% (incidence rate ratio (IRR) 0.723, 95% CI 0.592 to 0.885) the month after the campaign. In the 8 months after the 2021 campaign, 14 170 (95% CI 13 133 to 15 025) estimated cases were averted, a 24.7% reduction, and incidence in IRS districts dropped by 37.9% (IRR 0.621, 95% CI 0.462 to 0.835) immediately after IRS. Case incidence in control districts did not change following IRS either year (p>0.05) and the difference in incidence level change between IRS and control districts was significant both years (p<0.05). CONCLUSION: Deployment of clothianidin-based IRS was associated with a reduction in malaria case rates in two districts of Côte d'Ivoire following IRS deployment in 2020 and 2021. |
Entomological monitoring data driving decision-making for appropriate and sustainable malaria vector control in Cte d'Ivoire
Kouassi BL , Edi C , Ouattara AF , Ekra AK , Bellai LG , Gouaméné J , Kacou YAK , Kouamé JKI , Béké AO , Yokoli FN , Gbalegba CGN , Tia E , Yapo RM , Konan LY , N'Tamon RN , Akré MA , Koffi AA , Tanoh AM , Zinzindohoué P , Kouadio B , Yepassis-Zembrou PL , Belemvire A , Irish SR , Cissé NG , Flatley C , Chabi J . Malar J 2023 22 (1) 14 BACKGROUND: Entomological surveillance provides critical information on vectors for appropriate malaria vector control and strategic decision-making. The widely documented insecticide resistance of malaria vectors in Côte d'Ivoire requires that any vector control intervention deployment be driven by entomological data to optimize its effectiveness and appropriate resource allocations. To achieve this goal, this study documents the results of monthly vector surveillance and insecticide susceptibility tests conducted in 2019 and a review of all previous entomological monitoring data used to guide vector control decision making. Furthermore, susceptibility to pirimiphos-methyl and clothianidin was assessed in addition to chlorfenapyr and pyrethroids (intensity and piperonyl butoxide (PBO) synergism) tests previously reported. Vector bionomic data were conducted monthly in four sites (Sakassou, Béoumi, Dabakala and Nassian) that were selected based on their reported high malaria incidence. Adult mosquitoes were collected using human landing catches (HLCs), pyrethrum spray catches (PSCs), and human-baited CDC light traps to assess vector density, behaviour, species composition and sporozoite infectivity. RESULTS: Pirimiphos-methyl and clothianidin susceptibility was observed in 8 and 10 sites, respectively, while previous data reported chlorfenapyr (200 µg/bottle) susceptibility in 13 of the sites, high pyrethroid resistance intensity and increased mortality with PBO pre-exposure at all 17 tested sites. Anopheles gambiae sensu lato was the predominant malaria vector collected in all four bionomic sites. Vector density was relatively higher in Sakassou throughout the year with mean biting rates of 278.2 bites per person per night (b/p/n) compared to Béoumi, Dabakala and Nassian (mean of 48.5, 81.4 and 26.6 b/p/n, respectively). The mean entomological inoculation rate (EIR) was 4.44 infective bites per person per night (ib/p/n) in Sakassou, 0.34 ib/p/n in Beoumi, 1.17 ib/p/n in Dabakala and 1.02 ib/p/n in Nassian. The highest EIRs were recorded in October in Béoumi (1.71 ib/p/n) and Nassian (3.22 ib/p/n), in July in Dabakala (4.46 ib/p/n) and in May in Sakassou (15.6 ib/p/n). CONCLUSION: Based on all results and data review, the National Malaria Control Programme developed and implemented a stratified insecticide-treated net (ITN) mass distribution in 2021 considering new generation ITNs. These results also supported the selection of clothianidin-based products and an optimal spraying time for the first indoor residual spraying (IRS) campaign in Sakassou and Nassian in 2020. |
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