West Nile Virus Surveillance Report

The West Nile Virus Surveillance program is a grant funded program conducted by the Clinton County Health Department to monitor the presence of West Nile virus (WNV) in Clinton County by collecting and sampling mosquitoes and birds.  The Health Department began their 2017 WNV surveillance sampling season on May 23, collecting and sampling a total of 270 mosquito batches to date.  The first positive mosquito batch for WNV was on September 20th collected from Royal Lake Resort.  Additional sampling conducted by the Illinois Department of Public Health (IDPH) reported a positive mosquito sample on August 9th taken in Centralia.  This year the County Health Department collected and sent three bird specimens to the University of Illinois Veterinary Diagnostics Lab, all three tested negative for WNV.  In comparison, in 2016 two out of three submitted birds tested positive for WNV last Fall as the season was ending.  The Clinton County Health Department will be collecting bird specimens until October 12th and ask county residents to continue reporting dead birds.  Eligible birds must be recently deceased with no signs of decomposition or apparent cause of death other than disease.

Statewide IDPH statistics show WNV activity plateaued and declined to less than average activity for the month of August in 2017.   This is most evident with the decreased number of WNV human cases at 37 to date compared to 155 total cases in Illinois for 2016. The primary reason for this sudden activity can be related to the weather as August experienced record low temperatures.  In Illinois a total of 55 counties have reported WNV positive mosquito, bird and horse samples or human cases.  On September 20th IDPH reported the first death in Illinois due to WNV in Kankakee County.

Summer may be coming to an end, but the risk of contracting West Nile virus from a biting mosquito is not.  The mosquito season continues until the evening temperature consistently dips below 55°F, usually the middle of October, ending the WNV surveillance season.  Residents of Clinton County should continue protecting themselves from exposure to mosquito bites by practicing the three R’s.  REDUCE the number of mosquitoes and get rid of containers outside that hold water; REPEL mosquitoes by using insect repellent; and REPORT areas where water sits for more than a week.