Health officials said today they have found the first birds to be infected with West Nile virus this year in Illinois in LaSalle and Sandwich counties.

The birds were collected on June 8 and tested positive for the virus today, according to a statement from the Illinois Department of Public Health.

“With the temperature heating up, we could see more West Nile virus circulating. In hotter weather we typically see more West Nile virus activity,” Damon Arnold, the state public health director, said. “Although most cases of West Nile virus are mild, the virus can cause serious, life-altering and even fatal disease. That is why it is so important to protect yourself against mosquito bites by wearing insect repellent and getting rid of any standing water around your home.”

The agency said Tuesday that the first mosquitoes that tested positive for West Nile were found in Tazewell County on June 10.

The virus is transmitted by mosquitoes that have bitten an infected bird, according to the IDPH. “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 statement said. “Only about two people in 10 who are bitten by an infected mosquito will experience any illness.”

Symptoms include fever, headaches and body aches. In serious cases, the virus can cause meningitis, encephalitis and death.

For more information on West Nile virus, visit the IDPH Web site.

chicagobreaking@tribune.com