Investigation of West Nile Virus Infection Rates in Cx. tarsalis at Medicine Lake Wildlife Refuge and Ninepipe Wildlife Refuge 2011

Abstract

This study focused on the infection rate of West Nile virus in two Culex tarsalis mosquito populations in Montana. Medicine Lake Wildlife Refuge (MLWR) and Ninepipe Wildlife Refuge (NWR) Cx. tarsalis populations were chosen due to the variance in past viral incidence. Viral incidence at MLWR was thought to be higher due to higher infection rate in the Cx. tarsalis population possibly from favorable environmental factors. This study suggests, however, that high viral incidence may be a result of high Cx. tarsalis population as a proportion of the total mosquito population. Samples were homogenized and purified for RNA using a series of centrifugations through a specialized filter. A RT-PCR and Taqman assay then determined viral presence. No positive samples were collected from either collection site; a pooled infection rate program utilizing a 95% confidence interval determined there was no statistical difference in infection rates. Future studies can build upon this research by increasing sample number, recording differing temperatures and precipitation levels at both sites, and incorporating a temporal study in addition to the spatial analysis.