Press Release

May 23, 2008


First mosquitoes test positive for
West Nile virus in Illinois

SPRINGFIELD, Ill. – Dr. Damon T. Arnold, state public health director, today announced mosquito samples collected in Tazewell County and DuPage County have been confirmed as the first positive test results in Illinois this year for West Nile virus.

The Illinois Department of Public Health (IDPH) was notified by Tazewell and DuPage County Health Departments of the findings as part of its routine surveillance for West Nile virus. A positive mosquito sample was collected on May 16 in Creve Coeur and on May 19 in Bartlett.

“It’s not unexpected to receive a report of the first positive West Nile virus mosquitoes this time of May in Illinois.” said Dr. Arnold. “ West Nile virus activity has been present in the state since August 2001 and we expected to see activity again this year. This positive report should serve as a reminder to people to take precautions to protect themselves against mosquitoes.”

In 2007, the first positive mosquito sample was reported May 7 in DuPage County. Last year 46 of the state’s 102 counties were found to have a West Nile positive bird, mosquito, horse or human case. A total of 101 human cases of West Nile disease, including 4 deaths, were reported last year in Illinois.

Surveillance for West Nile virus in Illinois began on May 1 and includes laboratory tests on mosquitoes, dead crows, blue jays, robins and other perching birds as well as the testing of sick horses and humans with West Nile-like disease symptoms. Citizens who observe a sick or dying crow, blue jay, robin or other perching bird should contact their local health department, which will determine if the bird is to be picked up for testing.

West Nile virus is transmitted through the bite of a mosquito that has picked up the virus by feeding on an infected bird. Most people with the virus have no clinical symptoms of illness, but some may become ill three to 15 days after the bite of an infected mosquito. The first human case in Illinois is not usually reported until July or later.

Only about two people in 10 who are bitten by an infected mosquito will experience any illness. Illness from West Nile is usually mild and includes fever, headache and body aches, but serious illness, such as encephalitis and meningitis, and death are possible.

Persons older than 50 years of age have the highest risk of severe disease.

The best way to prevent West Nile disease or any other mosquito-borne illness is to reduce the number of mosquitoes around your home and to take personal precautions to avoid mosquito bites. Precautions include:

Avoid being outdoors when mosquitoes are most active, especially between dusk and dawn. Use prevention methods whenever mosquitoes are present.

  • When outdoors, wear shoes and socks, long pants and a long-sleeved shirt, and apply insect repellent that includes DEET, picaridin, oil of lemon eucalyptus or IR 3535 according to label instructions. Consult a physician before using repellents on infants.

  • Make sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or other openings. Try to keep doors and windows shut, especially at night.

  • Eliminate all sources of standing water that can support mosquito breeding, including water in bird baths, ponds, flowerpots, wading pools, old tires and any other receptacles. In communities where there are organized mosquito control programs, contact your municipal government to report areas of stagnant water in roadside ditches, flooded yards and similar locations that may produce mosquitoes.

Public health officials believe that a hot summer could increase mosquito activity and the risk of disease from West Nile virus.

Additional information about West Nile virus can be found on the Department’s Web site at

idph online home
idph online home

Illinois Department of Public Health
535 West Jefferson Street
Springfield, Illinois 62761
Phone 217-782-4977
Fax 217-782-3987
TTY 800-547-0466
Questions or Comments