Mosquitoes with West Nile virus were discovered in traps at two parks in Naperville.
The infected mosquitoes were found at Seager Park at 1163 Plank Road and Pioneer Park at 1212 South Washington Street, according to a Naperville Sun report.
City crews have sprayed the areas along with treating the surrounding catch basins so they can retest the traps starting Monday, the report said.
The first case of West Nile found in mosquitoes this year was confirmed in May, earlier than in 2011 when the first positive result came June 8.
There are no confirmed cases of the virus in humans so far this year.
There are several ways to prevent West Nile, according to the Center for Disease Control website. At the top of the list of preventions on the is using an insect repellent containing DEET, picaridin, oil of lemon eucalyptus, or IR 3535 while outdoors.