Mosquito Exposure and Malaria Morbidity: A Microlevel Analysis of Household Mosquito Populations and Malaria in a Population-Based Longitudinal Cohort in Western Kenya. (30th October 2019)

• Record Type: Journal Article
• Authors: O'Meara, Wendy Prudhomme; Simmons, Ryan; Bullins, Paige; Freedman, Betsy; Abel, Lucy; Mangeni, Judith; Taylor, Steve M; Obala, Andrew A
• Is Part Of: Journal of infectious diseases. Volume 221:Number 7(2020)
• Page Start: 1176
• Page End: 1184
• Publication Date: 2019-10-30
• Subjects: malaria -- Anopheles -- cohort -- insecticide-treated net; Communicable diseases -- Periodicals; Diseases -- Causes and theories of causation -- Periodicals; Medicine -- Periodicals; Communicable Diseases -- Periodicals; Electronic journals; 616.9
• DOI: 10.1093/infdis/jiz561
• Languages: English
• ISSNs: 0022-1899

Abstract

Abstract: Background: Malaria morbidity is highly overdispersed in the population. Fine-scale differences in mosquito exposure may partially explain this heterogeneity in individual malaria outcomes. Methods: In 38 households we explored the effect of household-level mosquito exposure and individual insecticide-treated net (ITN) use on relative risk (RR) of confirmed malaria. We conducted monthly active surveillance (n = 254; 2624 person-months) and weekly mosquito collection (2092 household-days of collection), and used molecular techniques to confirm human blood feeding and exposure to infectious mosquitoes. Results: Of 1494 female Anopheles (89.8% Anopheles gambiae sensu lato), 88.3% were fed, 51.9% had a human blood meal, and 9.2% were sporozoite infected. In total, 168 laboratory-confirmed malaria episodes were reported (incidence rate 0.064 episodes per person-month at risk; 95% confidence interval [CI], .055–.074). Malaria risk was directly associated with exposure to sporozoite-infected mosquitoes (RR, 1.24; 95% CI, 1.11–1.38). No direct effect was measured between ITN use and malaria morbidity; however, ITN use did moderate the effect of mosquito exposure on morbidity. Conclusions: Malaria risk increases linearly with vector density and feeding success for persons with low ITN use. In contrast, malaria risk among high ITN users is consistently low and insensitive to variation in mosquito exposure. Abstract : In this study, we measure the relationship between fine-scale spatiotemporal heterogeneity in exposure to infected and successfully fed malaria vectors, the incidence of malaria, and their interaction with insecticide-treated net use in a population-based cohort.