Heterogeneous impacts for malaria control from larviciding across villages and considerations for monitoring and evaluation
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
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 mosquito vector densities through LSM. The model simulates results of epidemiological trials 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 heterogeneity between villages within the same study indicate that the relative or absolute reductions in mosquito adult density observed in these trials cannot be simply extrapolated 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.
Editor(s)
Vernick, Kenneth
Date Issued
2025-07-28
Date Acceptance
2025-06-09
Citation
PLoS Pathogens, 2025, 21 (7)
ISSN
1553-7366
Publisher
Public Library of Science (PLoS)
Journal / Book Title
PLoS Pathogens
Volume
21
Issue
7
Copyright Statement
© 2025 Sherrard-Smith et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/40720548
PII: PPATHOGENS-D-25-00474
Subjects
Animals
Humans
Mosquito Control
Kenya
Anopheles
Cote d'Ivoire
Mosquito Vectors
Insecticides
Larva
Malaria, Falciparum
Malaria
Female
Adult
Publication Status
Published
Coverage Spatial
United States
Article Number
e1013287
Date Publish Online
2025-07-28