The Illinois Department of Public Health (IDPH) has confirmed the first human West Nile virus cases reported in Illinois for 2011. The Cook County Health Department reported a man in his 80s became ill earlier this month and the Franklin-Williamson Bi-County Health Department reported a man in his 30s became ill in July.

“West Nile virus activity in mosquitoes and birds continues to increase across Illinois, which means a higher risk of people contracting the virus,” said Illinois Department of Public Health Director Dr. Damon T. Arnold. “People should protect themselves against mosquitoes by wearing insect repellent and getting rid of any standing water around their homes.”

So far this year, 13 counties have reported mosquito batches, birds or a person testing positive for West Nile virus; Champaign, Cook, DuPage, Franklin, Gallatin, Jackson, Kane, Kendall, LaSalle, Macon, St. Clair, Tazewell and Will counties. The first West Nile virus positive results this year were collected on June 8 and included two birds from LaSalle County.

In 2010, the first positive mosquito samples were collected on June 3 in Gallatin County. Last year, 30 of the state’s 102 counties were found to have a West Nile positive bird, mosquito, horse or human case. A total of 61 human cases of West Nile disease were reported in Illinois last year, the first reported on August 31.

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.

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.