The Winnebago County Health Dpartment reports two mosquito batches have been tested positive for West Nile virus.
The health department says the areas were in the 61073 and 61108 zip codes. No human cases in Winnebago County have been reported.
Statewide, there have been six human cases so far this year.
Most people bitten have no symptoms but some may become ill for three to 15 days after the bite of an infected mosquito.