The Chester County Health Department (CCHD) conducts routine mosquito surveillance between May and October to monitor the risk of West Nile Virus (WNV). Surveillance includes the collection and testing of adult mosquitoes. Municipal surveillance reports keep municipalities informed of the present risk and engage in prevention activities. Municipalities are encouraged to take prevention measures to minimize standing water and encourage residents to practice prevention and protective measures of their own (see resources below). Municipalities that require additional measures to reduce risk will be contacted by CCHD.