Cook County Department of Public Health

An infection carried by mosquitoes. People get WNV from the bite of a mosquito that is infected with WNV. Mosquitoes become infected when they feed on a bird that has the virus in its blood. Once infected the mosquito can spread the virus to humans and other animals.

Anybody can become infected with WNV so it's important to protect yourself from mosquito bites. People over the age of 50 and those with chronic diseases such as heart disease or cancer may be more at-risk for serious illness. Most human cases occur in the late summer and early fall.

Most people infected with WNV have no symptoms of illness and never become ill. Some people may become ill 3-15 days after being bitten by an infected mosquito. Symptoms may include fever, headache and body aches. More severe symptoms may be a high fever, stiff neck, confusion, and muscle weakness.

Contact your primary healthcare provider if you are experiencing West Nile Virus symptoms.

During the summer, mosquitoes can develop in any standing water that lasts more than seven to 10 days. Protect yourself and your family:

• When outdoors between dusk and dawn, cover skin with lightly colored lose fitting clothing and use mosquito repellent with DEET, picaridin or oil of lemon eucalyptus. Always follow the directions on the label.
• Get rid of standing water around your home in pet bowls, flower pots, old tires, baby pools and toys.
• Make sure your doors and windows have tightly fitting screens and repair any tears or other openings.
• Keep weeds and grass cut short and keep gutters clean and free of debris.