Surveillance of Mosquito Species and Trap Type as Determinants of West Nile Virus Public Health Risk in one county in Virginia

Abstract

West Nile Virus (WNV) is currently the leading cause of mosquito-borne disease and related deaths in the United States. More than 66 species of mosquitoes are vectors of WNV, with Cx. pipiensrestuans being the main one. Different mosquito traps (BGSentinel, CDC, and Gravid) target mosquitoes at specific points in their life cycles, potentially influencing trap effectiveness and species detection. Our objective was to examine WNV positivity by (1) mosquito species and (2) trap type. We used Google Sheets and Google Earth to analyze longitudinal mosquito surveillance data from 2012-2025 across 95 fixed trap locations in Prince William County, Virginia. We quantified species composition among trap types and calculated temporal trends in WNV percent positivity. We found Cx. pipiensrestuans made up 93.82% of positive pools and 99.84% of gravid trap-positive pools, while boasting the highest species positivity rate of 7.52%. Most of the samples tested were trapped by Gravid traps (66.47%) followed by BGSentinel and CDC traps, 22.67% and 10.86%, respectively. Two species trapped by Gravid traps tested positive, five species trapped by CDC light traps and four species trapped by BGSentinel traps tested positive. Therefore, using multiple trap types is important to ensure that surveillance programs test a wide range of mosquito species circulating. This provides a more complete picture of WNV public health risk.