West Nile detected in St. Clair County mosquito test

The Illinois Department of Public Health says the first positive test for West Nile virus this year has been reported in a batch of mosquitoes collected in St. Clair County.

St. Clair County Health Department employees collected a positive mosquito batch on Tuesday in O’Fallon.

“West Nile virus activity is largely dependent on the weather and with the increased temperatures we’ve been seeing in Southern Illinois, mosquitoes carrying West Nile virus are becoming active,” said IDPH Director Nirav D. Shah. “We want to remind people not to be complacent. Take precautions to protect yourself by wearing insect repellent and getting rid of standing water around your home.”

Surveillance for West Nile virus in Illinois includes laboratory tests on mosquito batches, dead crows, blue jays, robins and other perching birds, as well as testing sick horses and humans with West Nile virus-like symptoms. People 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 will 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.

Common symptoms include fever, nausea, headache and muscle aches. Symptoms may last from a few days to a few weeks. However, four out of five people infected with West Nile virus will not show any symptoms. In rare cases, severe illness including meningitis or encephalitis, or even death, can occur.

People older than 50 and people with compromised immune systems are at higher risk for severe illness from West Nile Virus.

Last year, 50 counties in Illinois reported a West Nile virus-positive mosquito batch, bird or human case. For the 2014 season, IDPH reported 44 human cases (although human cases are underreported), including four deaths. No human cases of West Nile virus have been reported so far this year.

This story was originally published May 29, 2015 at 3:12 PM with the headline "West Nile detected in St. Clair County mosquito test."