Browsing by Author "Koudou, Benjamin"

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Heterogeneous impacts for malaria control from larviciding across villages and considerations for monitoring and evaluation
(PLOS Pathogens, 2025-07-28) Smith, Ellie; Fillinger, Ulrike; Jean, Philippe; Winskill, Peter; Koudou, Benjamin; Tchicaya, Emile; Sanou, Antoine; Okumu, Fredros; Opiyo, Mercy; Majambere, Silas; Hamlet, Arran; Giovanni, Charles; Lambert, Ben; Churcher, Thomas
Malaria vector control tools currently focus on insecticide treated nets (ITNs) and indoor residual spraying in malaria-endemic locations, but additional preventative strategies are needed to address protection gaps. Larval source management (LSM) includes larvicide application to aquatic habitat and an array of alternative forms of environmental efforts. An individual-based transmission model for falciparum malaria is used to demonstrate the theoretical benefit of suppressing malaria adult mos- quito vector densities through LSM. The model simulates results of epidemiologicaltrials from Western Kenya (a hilly area with papyrus swamps adjacent to human settlements and moderate to high perennial malaria transmission) and Côte d’Ivoire (an area with Sudanese climate, reducing vegetation cover and high transmission) that applied larvicide alongside ITNs, and investigates whether estimated changes in adult density can be used to project changes in human malaria. In the Western Kenya setting generalised linear models estimate 82% (90% credible intervals: 64% – 92%) and 88% (79% – 94%) reductions in the proportion of adult Anopheles funestus and Anopheles gambiae complex mosquitoes respectively as measured by CDC light traps. In Côte d’Ivoire, an 82% (56% – 93%) reduction of the dominant An. gambiae vector was estimated using standard window trap and pyrethrum spray catch. Both studies had variable village-level impacts. The transmission dynamics model predicted that these entomological impacts would result in a reduction in malaria prevalence in children of 6-months to 10-years of age of 48 – 72% in Kenya, and a 11 – 78% reduction in all-age clinical incidence across villages in Côte d’Ivoire, which are broadly consistent with the empirically observed outcomes. High hetero- geneity between villages within the same study indicate that the relative or absolute reductions in mosquito adult density observed in these trials cannot be simply extrap-olated to other regions. The LSM strategy adopted, unit area covered, and multiple environmental covariates all contribute to differences in indicators that could be used to assess entomological impacts and the corresponding epidemiological outcomes. This important malaria control tool was impactful across all sites examined, though further work is needed to understand how best to use this tool in the fight against malaria.
Meta-analysis on the entomological effects of differentially treated ITNs in a multi-site experimental hut study in sub-Saharan Africa
(BMC, 2025-02-04) Lissenden, Natalie; Bradley, John; Menze, Benjamin; Wondji, Charles; Edi, Constant; Koudou, Benjamin; N’Guessan, Raphael; Bayili, Koama; Diabaté, Abdoulaye; Mbewe, Njelembo; Emidi, Basiliana; Mosha, Jacklin; Manjurano, Alphaxard; Small, Graham; Oumbouke, Welbeck; Moore, Sarah; Nimmo, Derric; Snetselaar, Janneke
Background Restricting the placement of active ingredients (AIs) to specific panels on insecticide-treated nets (ITNs) has the potential to reduce the amount of AI required to treat a net. If the restricted placement of the AIs can exploit mosquito behaviour, particularly where they interact with the bed net interface, and not impact the net’s effectiveness, then the reduction in AI could result in cost reductions. Methods Nine individual experimental hut trials were conducted to compare the efficacy of three different partially-treated net relative to fully treated nets; roof-only treated nets, side-only treated nets, and nets with treated roof and pyrethroid-only side panels. These trials were conducted on a range of net products with different AIs, across a range of geographies in Africa (East and West), vector species (Anopheles gambiae, Anopheles coluzzii, Anopheles arabiensis, and Anopheles funestus), hut designs (East and West African style) and hosts (cows and humans). The combined data from these trials were analysed in a meta-analysis, and odds ratios for the effect of the different net designs on mortality and blood-feeding were estimated using mixed effects logistic regression. Results The results of this meta-analysis demonstrated that fully treated nets provide greater mosquito killing and reduction in blood-feeding effects than any configuration of insecticide treatment restricted to specific panels. Conclusions This meta-analysis showed that partially-treated net that restrict the insecticide treatment to specific panels of an ITN do not give equivalency or superiority in either mortality or blood-feeding inhibition to fully treated nets. The implications of these findings are discussed.