The first human case of West Nile virus in Illinois was confirmed in July 2012.
A woman in her sixties was diagnosed with the virus in Cook County.
Illinois Department of Public Health Director Dr. LaMar Hasbrouck said officials are seeing a significant increase in West Nile virus activity.
House mosquitoes, which typically carry West Nile virus, are not as noticeable as floodwater mosquitoes that swarm during rainy weather.
Dr. Hasbrouck said using insect repellent is important.
“Even if it does not look like there are a lot of mosquitoes out, house mosquitoes are stealthy biters and their virus infection rate is increasing rapidly, so make sure to use insect repellant,” said Dr. Hasbrouck.
A bird and mosquitoes in Cook County in May 2012 tested positive for West Nile virus, as did mosquito batches in DuPage County. West Nile has been found in birds and mosquitoes in 27 Illinois counties including Lee, Warren and LaSalle counties.
By this time last year, West Nile had been found in only seven Illinois counties.
The announcement of the first human case in the state came more than a month earlier than usual. Typically, the first human case of West Nile virus is announced in August each year.
Avoid being outdoors during nighttime hours when mosquitoes are most active. Keep doors and windows shut, especially at night.
Eliminate sources of standing water including ponds, bird baths, wading pools and other receptacles.
Wear insect repellent that contains DEET, picaridin, oil of lemon eucalyptus or IR 3535.
State officials update West Nile case numbers every Wednesday at this link: http://www.idph.state.il.us/envhealth/wnvsurveillance12.htm.