Abstract
BackgroundClimatic and environmental variables were used successfully by using models to predict Rift Valley fever (RVF) virus outbreaks in East Africa. However, these models are not replicable in the West African context due to a likely difference of the dynamic of the virus emergence. For these reasons specific models mainly oriented to the risk mapping have been developed. Hence, the areas of high vector pressure or virus activity are commonly predicted. However, the factors impacting their occurrence are poorly investigated and still unknown. In this study, we examine the impact of climate and environmental factors on the likelihood of occurrence of the two main vectors of RVF in West Africa (Aedes vexans and Culex poicilipes) hotspots.MethodsWe used generalized linear mixed models taking into account spatial autocorrelation, in order to overcome the default threshold for areas with high mosquito abundance identified by these models. Getis’ Gi*(d) index was used to define local adult mosquito abundance clusters (hotspot).ResultsFor Culex poicilipes, a decrease of the minimum temperature promotes the occurrence of hotspots, whereas, for Aedes vexans, the likelihood of hotspot occurrence is negatively correlated with relative humidity, maximum and minimum temperatures. However, for the two vectors, proximity to ponds would increase the risk of being in an hotspot area.ConclusionsThese results may be useful in the improvement of RVF monitoring and vector control management in the Barkedji area.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1399-3) contains supplementary material, which is available to authorized users.
Highlights
Climatic and environmental variables were used successfully by using models to predict Rift Valley fever (RVF) virus outbreaks in East Africa
For Aedes vexans, in 2005, the first half of August had the highest hotspots numbers (11) whereas in 2006 it was during the second half of September (11)
Our study focused on Cx. poicilipes and Ae. vexans because they are the most abundant and are considered as the main vectors of RVF in the area
Summary
Climatic and environmental variables were used successfully by using models to predict Rift Valley fever (RVF) virus outbreaks in East Africa. These models are not replicable in the West African context due to a likely difference of the dynamic of the virus emergence. We examine the impact of climate and environmental factors on the likelihood of occurrence of the two main vectors of RVF in West Africa (Aedes vexans and Culex poicilipes) hotspots. Talla et al Parasites & Vectors (2016) 9:111 were found associated to RVFV but the two dominant vectors are Culex poicilipes and Aedes vexans [12,13,14] All these vectors breed in temporary ponds that are flooded after the first rains usually in July. These temporary ponds represent the main source of water for people, livestock and wildlife in this area for at least 6 months per year [14, 15]
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