Blood Meal Analysis and Arbovirus Detection in A Sylvatic Aedes Chaussieri at Oloolua Forest, Kenya

Arboviral pathogens are a growing public health problem especially in Africa. Bridge vectors facilitate virus transmission to humans from forest or sylvatic environments although the species involved are not fully understood. In this study, we investigated the role of Aedes chaussieri in sylvatic arboviral transmission cycle. Archived samples collected from the Oloolua Forest in the outskirts of Nairobi, Kenya, were analyzed in pools for viruses by cell culture in Vero Cells followed by RT-PCR and sequencing. Blood-fed specimens were processed for host meal sources by PCR and sequencing of a portion of the mitochondrial 12S ribosomal RNA gene. Viral screening revealed West Nile virus (WNV) infection in two pools after cell culture and subsequent molecular identification using primers targeting polyprotein gene specific to Flaviviridae family.Sequences of the isolates (259-268 bp) were 99% identical to each other and closely related to a lineage 1 WNV strain isolated from the mosquito Culex poicilipes in Senegal (98% identity).Blood meal patterns revealed overwhelming feeding on tree hyrax (70.9%, 197/328), followed by antelope (16.2%, 45/328), human (8.6%, 24/328) and minor representation of other avian and mammalian wildlife species. The results unravel novel association of WNV with Ae. chaussieri that not only feeds largely on wildlife species but also humans, thus, can serve as potential bridge vector of the virus. Further studies are recommended to understand the vectorial capacity of this mosquito species.