Landscape ecology of sylvatic chikungunya virus and mosquito vectors in southeastern Senegal.

Diawo Diallo,Ibrahima Dia,Douglas Watts,Cheikh T Diagne,Michaela Buenemann,Scott C Weaver,Mawlouth Diallo,Ousmane Faye,Yamar Ba,Rubing Chen,Amadou A Sall,Oumar Faye,Kathryn A Hanley

doi:10.1371/journal.pntd.0001649

Abstract

The risk of human infection with sylvatic chikungunya (CHIKV) virus was assessed in a focus of sylvatic arbovirus circulation in Senegal by investigating distribution and abundance of anthropophilic Aedes mosquitoes, as well as the abundance and distribution of CHIKV in these mosquitoes. A 1650 km2 area was classified into five land cover classes: forest, barren, savanna, agriculture and village. A total of 39,799 mosquitoes was sampled from all classes using human landing collections between June 2009 and January 2010. Mosquito diversity was extremely high, and overall vector abundance peaked at the start of the rainy season. CHIKV was detected in 42 mosquito pools. Our data suggest that Aedes furcifer, which occurred abundantly in all land cover classes and landed frequently on humans in villages outside of houses, is probably the major bridge vector responsible for the spillover of sylvatic CHIKV to humans.

Highlights

Chikungunya virus (CHIKV, genus Alphavirus, family Togaviridae) is maintained in a sylvatic cycle in West Africa, where it is transmitted by a suite of sylvatic Aedes mosquito species among a group of reservoir hosts, including African green monkeys (Chlorocebus sabaeus), patas monkeys (Erythrocebus patas) and Guinea baboons (Papio papio), and possibly reservoir hosts in other orders of mammals [1,2,3]
Chikungunya is a mosquito-borne virus that infects and sickens people in many tropical, urban regions of the world. This virus circulates in forest cycles of West Africa, where mosquitoes transmit it among non-human primates
Little is known about the environmental factors that influence the abundance and distribution of mosquito vectors that participate in the forest cycle of this virus or about specific mosquitoes that are likely to act as bridge vectors

Summary

Introduction

Chikungunya virus (CHIKV, genus Alphavirus, family Togaviridae) is maintained in a sylvatic cycle in West Africa, where it is transmitted by a suite of sylvatic Aedes mosquito species among a group of reservoir hosts, including African green monkeys (Chlorocebus sabaeus), patas monkeys (Erythrocebus patas) and Guinea baboons (Papio papio), and possibly reservoir hosts in other orders of mammals [1,2,3]. Aedes albopictus serves as a vector of CHIKV in the human cycle. This species, which originated from Asia, is a rapidly expanding exotic species in the Americas, Europe and Africa [3,4] and was responsible for explosive CHIKV outbreaks in the Indian Ocean, Asia, Europe and Central Africa [1,2,3,4,5,6]. Recent transmission following the arrival of infected travelers has been observed in Europe [3] and there is considerable concern that CHIKV will invade the Americas, where both of its major peridomestic vectors are abundant and infected travelers have arrived from Asia and the Indian Ocean [9]

Methods

Results

Conclusion