Chester County Health Department - West Nile Virus Surveillance Report

Published on August 24, 2026

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The Chester County Health Department conducts routine mosquito surveillance between May - October to monitor the risk of West Nile Virus, which includes the collection and testing of adult mosquitoes. The following data was compiled by the CCHD for Tredyffrin Township - click here(PDF, 255KB).

WNV-positive samples have been detected in Tredyffrin Township at Cedar Hollow Park, Wilson Farm Park, and Strafford Park, all on August 13, 2026. CCHD will continue to monitor mosquito populations in Tredyffrin throughout the remainder of the season and communicate our findings should additional positive samples be detected. The CCHD team will work to identify mosquito larval habitat at or nearby these sites where treatments can be performed with BTI-based larval control products. Visit the Chester County Health Department's website for more information on Mosquito-Bourne Diseases, Bite Prevention, and more.