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CHICAGO — Illinois health officials confirmed the first human case of West Nile virus in Illinois in 2021 as a Cook County resident in his 80s tested positive for the virus after becoming ill in mid-June.

“West Nile virus is something we see every year in Illinois and it is important that people take steps to prevent mosquito bites and the viruses they carry by wearing insect repellent and getting rid of standing water around their homes,” IDPH Director Dr. Ngozi Ezike said.

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In 2020, 42 human cases of West Nile were confirmed in Illinois (although human cases are often underreported), with four people dying from the virus.

West Nile is transmitted through the bite of a Culex pipiens mosquito, commonly called a house mosquito. The mosquitos contract 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, 80 percent of people infected with the virus will not show any symptoms. In rare cases, severe illness including meningitis or even death, can occur.

People older than 60 and people with weakened immune systems are at higher risk for severe illness from West Nile virus.