Sign up to receive Chesco Public Health updates here. This is the fastest way to receive information. Please encourage your municipality to post these releases on receipt on their own web site.
See spraying (“adulticide events”) in Chester County here. This site has unfortunately not been updated since 8/9/18.
See recent Chesco Health Department News (including about mosquito spraying) here. There no longer seems to be a single site for all mosquito-related releases.
See Chesco West Nile virus surveillance data here. This site has unfortunately not been updated since 7/30/18. When the site is functional, data are updated weekly and are cumulative except that the Vector Index is for the past 3 weeks. The Vector Index is a score based on the number of WNV-positive traps and the total number of traps. The Vector Index at which the County decides to spray a given location can vary.
See WNV “hot zones” in PA, for the preceding 3 weeks here. Also similar information for previous years. This site has unfortunately not been updated since 8/14/18.
See and sign up for a daily (on weekdays) report on WNV-carrying mosquitoes trapped in each county here. You can also see reports posted every few days showing the number of human, avian, and mosquito WNV positives for each county.
As mentioned above several of the state sites seem to have suffered a breakdown in the middle of the 2018 mosquito season, so we can’t really generalize till we get better data. The last site above shows that there were 2 human cases out of 134 in the state. We have not heard of any WNV deaths.
There were huge numbers of mosquito pools testing positive, so it is obvious that mosquitoes do not transmit WNV to humans effectively and/or humans resist WNV without diagnosis.
Statewide WNV data by county here. There were 156 Chester County positives out of 751 mosquito pools tested in 2017. Meanwhile, there were 20 known human cases in all PA, 4 of them in Chester County (however, “*This number may include positive cases for pathogens other than West Nile Virus”), and no WNV-caused deaths in the state (compare to well over 2,000 annual opioid-related deaths in PA).
There were 5 Chesco “spraying events” affecting 7 municipalities in 2017, in Thornbury/Birmingham. Downingtown/East Caln, Phoenixville, East Bradford, and Spring City. You can see the press releases by searching our site.
See statewide data on West Nile virus by county here. In 2014-15-16, Chester County had a total of 3 known human cases and no known WNV-related deaths.
In 2016, 4 Chesco releases concerned mosquitoes and WNV, including 2 about spraying. See here.