Explaining variation in adult Anopheles indoor resting abundance: the relative effects of larval habitat proximity and insecticide-treated bed net use

Malaria Journal

Research

M. Nabie Bayoh¹  Robert S. McCann²  David W. MacFarlane³  Joseph P. Messina⁴  Edward D. Walker⁵  John E. Gimnig⁶  Emanuele Giorgi⁷ 

[1] Centre for Global Health Research, Kenya Medical Research Institute/Centers for Disease Control and Prevention, Kisumu, Kenya;Department of Entomology, Michigan State University, East Lansing, MI, USA;Department of Forestry, Michigan State University, East Lansing, MI, USA;Department of Geography, Environment, and Spatial Sciences, Michigan State University, East Lansing, MI, USA;Department of Microbiology and Molecular Genetics, Michigan State University, 567 Wilson Road, 2215 Biomedical Physical Sciences Building, 48824-4320, East Lansing, MI, USA;Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, USA;Lancaster Medical School, Lancaster University, Lancaster, UK;

关键词: Spatial heterogeneity;    Larval habitats;    Malaria vectors;    Anopheles gambiae;    Anopheles arabiensis;    Anopheles funestus;    Generalized linear models;    Geostatistical models;   

DOI  :  10.1186/s12936-017-1938-1

 received in 2017-02-27, accepted in 2017-07-13,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundSpatial determinants of malaria risk within communities are associated with heterogeneity of exposure to vector mosquitoes. The abundance of adult malaria vectors inside people’s houses, where most transmission takes place, should be associated with several factors: proximity of houses to larval habitats, structural characteristics of houses, indoor use of vector control tools containing insecticides, and human behavioural and environmental factors in and near houses. While most previous studies have assessed the association of larval habitat proximity in landscapes with relatively low densities of larval habitats, in this study these relationships were analysed in a region of rural, lowland western Kenya with high larval habitat density.Methods525 houses were sampled for indoor-resting mosquitoes across an 8 by 8 km study area using the pyrethrum spray catch method. A predictive model of larval habitat location in this landscape, previously verified, provided derivations of indices of larval habitat proximity to houses. Using geostatistical regression models, the association of larval habitat proximity, long-lasting insecticidal nets (LLIN) use, house structural characteristics (wall type, roof type), and peridomestic variables (cooking in the house, cattle near the house, number of people sleeping in the house) with mosquito abundance in houses was quantified.ResultsVector abundance was low (mean, 1.1 adult Anopheles per house). Proximity of larval habitats was a strong predictor of Anopheles abundance. Houses without an LLIN had more female Anopheles gambiae s.s., Anopheles arabiensis and Anopheles funestus than houses where some people used an LLIN (rate ratios, 95% CI 0.87, 0.85–0.89; 0.84, 0.82–0.86; 0.38, 0.37–0.40) and houses where everyone used an LLIN (RR, 95% CI 0.49, 0.48–0.50; 0.39, 0.39–0.40; 0.60, 0.58–0.61). Cooking in the house also reduced Anopheles abundance across all species. The number of people sleeping in the house, presence of cattle near the house, and house structure modulated Anopheles abundance, but the effect varied with Anopheles species and sex.ConclusionsVariation in the abundance of indoor-resting Anopheles in rural houses of western Kenya varies with clearly identifiable factors. Results suggest that LLIN use continues to function in reducing vector abundance, and that larval source management in this region could lead to further reductions in malaria risk by reducing the amount of an obligatory resource for mosquitoes near people’s homes.

【 授权许可】

CC BY   
© The Author(s) 2017

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