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Predicting the impact of outdoor vector control interventions on malaria transmission intensity from semi-field studies

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dc.contributor.author Adrian, Denz
dc.contributor.author Margaret M, Njoroge
dc.contributor.author Mgeni M, Tambwe
dc.contributor.author Clara, Champagne
dc.contributor.author Fredros, Okumu
dc.contributor.author JoopJ.A, van Loon
dc.contributor.author Alexandra, Hiscox
dc.contributor.author Adam, Saddler
dc.contributor.author Ulrike, Fillinger
dc.contributor.author Sarah J, Moore
dc.contributor.author Nakul, Chitnis
dc.date.accessioned 2021-07-13T12:32:48Z
dc.date.available 2021-07-13T12:32:48Z
dc.date.issued 2021
dc.identifier.uri http://hdl.handle.net/123456789/1487
dc.description.abstract Background:Semi-field experiments with human landing catch (HLC) measure as the outcome are an important step in the development of novel vector control interventions against outdoor transmission of malaria since they provide good estimates of personal protection. However, it is often infeasible to determine whether the reduction in HLC counts is due to mosquito mortality or repellency, especially considering that spatial repellents based on volatile pyrethroids might induce both. Due to the vastly different impact of repellency and mortality on transmission, the community-level impact of spatial repellents can not be estimated from such semi-field experiments.Methods:We present a new stochastic model that is able to estimate for any product inhibiting outdoor biting, its repelling effect versus its killing and disarming (preventing host-seeking until the next night) effects, based only on time-stratified HLC data from controlled semi-field experiments. For parameter inference, a Bayesian hierarchical model is used to account for nightly variation of semi-field experimental conditions. We estimate the impact of the products on the vectorial capacity of the given Anopheles species using an existing mathematical model. With this methodology, we analysed data from recent semi-field studies in Kenya and Tanzania on the impact of transfluthrin-treated eave ribbons, the odour-baited Suna trap and their combination (push–pull system) on HLC of Anopheles arabiensis in the peridomestic area.Results:Complementing previous analyses of personal protection, we found that the transfluthrin-treated eave ribbons act mainly by killing or disarming mosquitoes. Depending on the actual ratio of disarming versus killing, the vectorial capacity of An.arabiensis is reduced by 41 to 96% at 70% coverage with the transfluthrin-treated eave rib-bons and by 38 to 82% at the same coverage with the push–pull system, under the assumption of a similar impact on biting indoors compared to utdoors.Conclusions:The results of this analysis of semi-field data suggest that transfluthrin-treated eave ribbons are a promis-ing tool against malaria transmission by An.arabiensis in the peridomestic area, since they provide both personal and community protection. Our modelling framework can estimate the community-level impact of any tool intervening during the mosquito host-seeking state using data from only semi-field experiments with time-stratified HLC. en_US
dc.description.sponsorship Innovative Vector Control Consortium (IVCC) ICIPE UK Department for International Development (DFID) Swedish International Development Cooperation Agency (Sida) Swiss Agency for Development and Coopera-tion (SDC) Democratic Republic of Ethiopia Kenyan Government Swiss National Science Foundation en_US
dc.publisher BMC Parasite and Vector en_US
dc.rights Attribution-NonCommercial-ShareAlike 3.0 United States *
dc.rights.uri http://creativecommons.org/licenses/by-nc-sa/3.0/us/ *
dc.subject Malarial en_US
dc.subject Anopheles arabiensis en_US
dc.subject Vector control en_US
dc.subject Outdoor transmission en_US
dc.subject Spatial repellent en_US
dc.subject Volatile pyrethroids en_US
dc.subject Semi-field experiments en_US
dc.subject Community-level impact en_US
dc.subject Stochastic modelling en_US
dc.subject Hierarchical Bayesian mode en_US
dc.title Predicting the impact of outdoor vector control interventions on malaria transmission intensity from semi-field studies en_US
dc.type Article en_US


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