Arbovirus Prevalence in Mosquitoes, Kenya

A. Desiree LaBeaud,Eric M. Muchiri,Charles H. King,Amy G. Hise,Laura J. Sutherland,Peter A. Zimmerman,Samuel Muiruri,Laurie R. Gray

doi:10.3201/eid1702.091666

Abstract

Few studies have investigated the many mosquito species that harbor arboviruses in Kenya. During the 2006–2007 Rift Valley fever outbreak in North Eastern Province, Kenya, exophilic mosquitoes were collected from homesteads within 2 affected areas: Gumarey (rural) and Sogan-Godud (urban). Mosquitoes (n = 920) were pooled by trap location and tested for Rift Valley fever virus and West Nile virus. The most common mosquitoes trapped belonged to the genus Culex (75%). Of 105 mosquito pools tested, 22% were positive for Rift Valley fever virus, 18% were positive for West Nile virus, and 3% were positive for both. Estimated mosquito minimum infection rates did not differ between locations. Our data demonstrate the local abundance of mosquitoes that could propagate arboviral infections in Kenya and the high prevalence of vector arbovirus positivity during a Rift Valley fever outbreak.

Highlights

Few studies have investigated the many mosquito species that harbor arboviruses in Kenya
We investigated the local abundance of mosquitoes in Kenya that are infected with Rift Valley fever (RVF) virus (RVFV) and West Nile virus (WNV); mosquitoes were collected near human habitation during a period of prolonged heavy rainfall
Domestic ungulates are a principal source of transmissible RVFV, and human infection has been associated with direct animal contact, with cattle, sheep, and goats [2,9,12]

Summary

Introduction

Few studies have investigated the many mosquito species that harbor arboviruses in Kenya. Mosquitoes (n = 920) were pooled by trap location and tested for Rift Valley fever virus and West Nile virus. Our data demonstrate the local abundance of mosquitoes that could propagate arboviral infections in Kenya and the high prevalence of vector arbovirus positivity during a Rift Valley fever outbreak. Domestic ungulates are a principal source of transmissible RVFV, and human infection has been associated with direct animal contact, with cattle, sheep, and goats [2,9,12] It is unclear which, if any, animal species maintain RVFV during interepidemic periods, and it is possible that RVFV is maintained solely within arthropod vectors during these periods [13].

Methods

Results

Conclusion