245 - Ecologic factors contributing to West Nile virus hyperendemicity in South Carolina, USA

Abstract: West Nile virus (WNV) is an endemic arboviral infection in the USA that has evolved as a virus and ecologically since it’s introduction 25 years ago. Our work in South Carolina has unearthed novel vectors, contemporary Culex quinquefasciatus habitat patterns and human transmission spillover foci. Specifically, Richland County residents display a 5.5 times greater WNV seroprevalence than the national average and they presented with unusual epidemiologic risk factors such as self-reported repellent use and actively performing ‘tip-and-toss’ mosquito habitat mitigation strategies in their yards. Vector analysis in this hyperendemic county revealed that Cu. quinquefasciatus mosquitos clustered in affluent urban neighborhoods with greater tree canopy and abundant domestic waterbodies. Further, Cu. quinquefasciatus abundance was greatest when climate variance was nominal in the 72 hours proceeding mosquito collection. Collaborations with the county zoo revealed several Icosta americana collected off local raptors were WNV positive, suggesting this secondary vector may play an important role in WNV transmission. In closing, this collective vector-human-pathogen ecological study presents emerging transmission factors as WNV continues to persist in the USA.