Wood River, Ill. (KMOV.com) -- Madison County Health Department announced Friday that a mosquito batch in Madison County has tested positive for West Nile Virus.
The pool of mosquitoes was collected Thursday and found to be positive Friday.
Positive batches have also been found in Cook, DuPage and Gallatin counties. No humans have been affected but a bird tested positive in Cook County on May 16.
West Nile Virus is transmitted through a mosquito bite from a mosquito that has fed from an infected bird.