SPRINGFIELD, IL – Dr. Eric Whitaker, state public health director, today announced laboratory tests have identified the state's first human case this year of a mosquito-borne disease.

Dr. Whitaker said a 45-year-old Evanston woman became ill June 12 and recently completed laboratory tests by the Illinois Department of Public Health and the U.S. Centers for Disease Control and Prevention (CDC) found she had Eastern equine encephalitis, an uncommon disease transmitted by the bite of an infected mosquito. Because this is a rare infection in humans, additional laboratory tests are being conducted by the CDC to confirm the diagnosis.

The woman, who complained of a severe headache and stiff neck, did not require hospitalization and has recovered without any complications. The only other human case of Eastern equine encephalitis in the United States this year was in Georgia.

"No humans in Illinois have ever been infected with Eastern equine encephalitis, but in past years wild birds have been found with the virus," Dr. Whitaker said. "While this is an unusual disease for our state, it is not totally unexpected and the prevention advice to the public is the same as that for West Nile virus."

While it is not known where the woman was bitten by an infected mosquito, she reported travel to the Evanston area and southeastern Wisconsin. Local and state public health officials have increased surveillance for Eastern equine encephalitis in Evanston and surrounding areas, as well as other locations in the state.

So far this year, nine birds and five mosquito pools in nine counties have been identified with West Nile virus, but no human cases have been identified. Last year, Illinois led the nation with 877 cases of West Nile virus, including 64 deaths.

Dr. Whitaker encouraged individuals to take common sense measures to protect themselves and their families from mosquito-borne disease:

• Stay indoors at dawn, dusk and early evening. If outdoors at these times, wear shoes and socks, long pants and a long-sleeved shirt. Loose-fitting, light-colored clothing is best.
• Use mosquito repellent containing 10 percent to 25 percent DEET when it is necessary to be outdoors, applied sparingly to exposed skin or clothing, as indicated on the repellent label. Consult a physician before using repellents on young children.
• Check for and repair tears in residential screens, including porches and patios.
• Eliminate stagnant water in birdbaths, ponds, flower pots, old tires and any other receptacles in which mosquitoes might breed.

Symptoms of Eastern equine encephalitis include high fever, nausea, muscle aches, stiff neck and intense headaches. Once bitten by an infected mosquito, symptoms may develop in approximately four to 10 days.

The Culiseta melanura mosquito is the primary carrier of Eastern equine encephalitis virus and tends to prefer swampy areas and feeds primarily on birds. Typically only isolated cases occur, although clusters of cases may be seen in horses and bird populations.

Since 1964, there have only been 153 confirmed cases of Eastern equine encephalitis in the United States, according to the CDC, mostly in northeastern states. Cases have been reported in previous years in Indiana, Michigan and Wisconsin.