Shifts in malaria vector species composition and transmission dynamics along the Kenyan coast over the past 20 years

Malaria Journal

Research

John C Beier¹  Joseph Keating²  Ephantus J Muturi³  John Githure⁴  Benedict O Orindi⁵  Hellen Gatakaa⁵  Christian Borgemeister⁵  Joseph Nzovu⁶  Janet T Midega⁶  Charles M Mbogo⁷  Joseph M Mwangangi⁷ 

[1] Department of Epidemiology and Public Health, University of Miami Miller School of Medicine, Miami, Florida, USA;Department of Global Health Systems and Development, Tulane University School of Public Health and Tropical Medicine, New Orleans, USA;Illinois Natural History Survey, University of Illinois, Urban-Champaign, Illinois, USA;Integrated Vector Management Coordinator at the Research Triangle Institute (RTI), Kigali, Rwanda;Integrated Vector and Disease Management Cluster, International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya;Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine Research, Kilifi, Coast, Kenya;Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine Research, Kilifi, Coast, Kenya;Integrated Vector and Disease Management Cluster, International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya;

关键词: Malaria;    Malaria Transmission;    Malaria Vector;    Malaria Prevalence;    Anopheles Funestus;   

DOI  :  10.1186/1475-2875-12-13

 received in 2012-11-02, accepted in 2013-01-06,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundOver the past 20 years, numerous studies have investigated the ecology and behaviour of malaria vectors and Plasmodium falciparum malaria transmission on the coast of Kenya. Substantial progress has been made to control vector populations and reduce high malaria prevalence and severe disease. The goal of this paper was to examine trends over the past 20 years in Anopheles species composition, density, blood-feeding behaviour, and P. falciparum sporozoite transmission along the coast of Kenya.MethodsUsing data collected from 1990 to 2010, vector density, species composition, blood-feeding patterns, and malaria transmission intensity was examined along the Kenyan coast. Mosquitoes were identified to species, based on morphological characteristics and DNA extracted from Anopheles gambiae for amplification. Using negative binomial generalized estimating equations, mosquito abundance over the period were modelled while adjusting for season. A multiple logistic regression model was used to analyse the sporozoite rates.ResultsResults show that in some areas along the Kenyan coast, Anopheles arabiensis and Anopheles merus have replaced An. gambiae sensu stricto (s.s.) and Anopheles funestus as the major mosquito species. Further, there has been a shift from human to animal feeding for both An. gambiae sensu lato (s.l.) (99% to 16%) and An. funestus (100% to 3%), and P. falciparum sporozoite rates have significantly declined over the last 20 years, with the lowest sporozoite rates being observed in 2007 (0.19%) and 2008 (0.34%). There has been, on average, a significant reduction in the abundance of An. gambiae s.l. over the years (IRR = 0.94, 95% CI 0.90–0.98), with the density standing at low levels of an average 0.006 mosquitoes/house in the year 2010.ConclusionReductions in the densities of the major malaria vectors and a shift from human to animal feeding have contributed to the decreased burden of malaria along the Kenyan coast. Vector species composition remains heterogeneous but in many areas An. arabiensis has replaced An. gambiae as the major malaria vector. This has important implications for malaria epidemiology and control given that this vector predominately rests and feeds on humans outdoors. Strategies for vector control need to continue focusing on tools for protecting residents inside houses but additionally employ outdoor control tools because these are essential for further reducing the levels of malaria transmission.

【 授权许可】

CC BY   
© Mwangangi et al.; licensee BioMed Central Ltd. 2013