Vector control remains at the forefront of the fight against malaria. The unprecedented expansion of long-lasting insecticide treated mosquito nets and indoor residual spraying programmes has reduced the burden of disease across the world. However, there is a growing realisation that the effectiveness of these tools is under threat.
Insecticide resistance is a key concern for all malaria control programmes though it is still unclear what public health impact it will have. Working with the World Health Organisation and the Innovative Vector Control Consortium we are using mathematical models to predict the public health impact of different types of insecticide resistance from entomological data. In collaboration with the Liverpool School of Tropical Medicine and Le Centre National de Recherche et de Formation sur le Paludisme, Burkina Faso, we are directly assessing whether pyrethroid resistance can explain why clinical incidence in field sites in Burkina Faso has remained high despite widespread use of long-lasting insecticide treated bednets. Given the clear need novel insecticides that are safe for people to sleep under, semi-field studies, such as experimental hut trials, are an extremely useful way to assess new products relatively quickly. Novel methods are also being developed to test alternative technologies. We are using statistical methods to examine how robust these assays are, to ensure that these studies are sufficiently powered.
We have developed a series of Africa-wide maps depicting the geographic spread of resistance to pyrethroid and DDT insecticides in mosquito vectors of malaria from the Anopheles gambiae complex. These maps demonstrate the dramatic spread of resistance in a recent 10-15 year period. Working with the Liverpool School of Tropical Medicine we are developing spatial modelling approaches to link phenotypic resistance to underlying genetic mechanisms that drive resistance in mosquito species.
Publications
Green N, Agossa F, Yovogan B, Oxborough R, Kitau J, Müller P, Constant E, Rowland M, Tchacaya EFS, Benjamin KG, Churcher TS, Betancourt M, Sherrard-Smith Eet al., 2022, An evidence synthesis approach for combining different data sources illustrated using entomological efficacy of insecticides for indoor residual spraying, PLoS One, Vol: 17, Pages: e0263446-e0263446, ISSN: 1932-6203
Sherrard-Smith E, Winskill P, Hamlet A, Ngufor C, N'Guessan R, Guelbeogo MW, Sanou A, Nash RK, Hill A, Russell EL, Woodbridge M, Tungu P, Kont MD, McLean T, Fornadel C, Richardson JH, Donnelly MJ, Staedke SG, Gonahasa S, Protopopoff N, Rowland M, Churcher TSet al., 2022, Optimising the deployment of vector control tools against malaria: a data-informed modelling study, The Lancet Planetary Health, Vol: 6, Pages: e100-e109, ISSN: 2542-5196
Martin JL, Messenger LA, Mosha FW, Lukole E, Mosha JF, Kulkarni M, Churcher TS, Sherrard-Smith E, Manjurano A, Protopopoff N, Rowland Met al., 2022, Durability of three types of dual active ingredient long-lasting insecticidal net compared to a pyrethroid-only LLIN in Tanzania: methodology for a prospective cohort study nested in a cluster randomized controlled trial., Malaria Journal, Vol: 21, Pages: 96-96, ISSN: 1475-2875
Nash et al 2021 Systematic review of the entomological impact of insecticide-treated nets evaluated using experimental hut trials in Africa. Current Research in Parasitology & Vector-Borne Diseases.1. 100047.
Hancock, P.A., Lynd, A., Wiebe, A., Devine, M., Essandoh, J., Wat’senga, F., Manzambi, E.Z., Agossa, F., Donnelly, M.J., Weetman, D., and Moyes, C.L. Modelling spatiotemporal trends in the frequency of genetic mutations conferring insecticide target-site resistance in African mosquito malaria vector species. BMC Biol 20, 46 (2022).
Moyes, C. L., Athinya, D. K., Seethaler, T., Battle, K. E., Sinka, M., Hadi, M. P., Hemingway, J., Coleman, M. & Hancock, P. A. 2020. Evaluating insecticide resistance across African districts to aid malaria control decisions. PNAS 117, 22042-22050.
Hancock, P.A., Lynd, A., Wiebe, A., Devine, M., Essandoh, J., Wat’senga, F., Manzambi, E.Z., Agossa, F., Donnelly, M.J., Weetman, D., and Moyes, C.L. Modelling spatiotemporal trends in the frequency of genetic mutations conferring insecticide target-site resistance in African mosquito malaria vector species. BMC Biol 20, 46 (2022).
Hancock, P. A., Wiebe, A., Gleave, K. A., Bhatt, S., Cameron, E., Trett, A., Weetman, D., Smith, D. L., Hemingway, J., Coleman, M., Gething, P.W. and Moyes, C.L. 2018. Associated patterns of insecticide resistance in field populations of malaria vectors across Africa. PNAS 115, 5938-5943.
Sherrard-Smith E, Griffin J, Winskill P, Corbel V, Pennetier C, Djénontin A, Moore S, Richardson J, Müller P, Edi C, Protopopoff N, Oxborough R, Agossa F, N'Guessan R, Rowland M, Churcher Tet al., 2018, Systematic review of indoor residual spray efficacy and effectiveness against Plasmodium falciparum in Africa, Nature Communications, Vol: 9, ISSN: 2041-1723
Churcher TS, Lissenden N, Griffin JT, Worrall E, Ranson Het al., 2016, The impact of pyrethroid resistance on the efficacy and effectiveness of bednets for malaria control in Africa, eLife, Vol: 5, ISSN: 2050-084X