West Nile virus found in McHenry County mosquito

West Nile virus has been detected in mosquitoes in McHenry County, according to health officials.

The mosquitoes were collected from Lake in the Hills on June 2 and mark the first positive test for the virus in mosquitoes in the 2025 season in McHenry County. No cases have been reported yet in humans in McHenry County this year.

Mosquito season runs from May to October annually, and the risk of transmission of the virus lasts until “the first hard frost,” according to a press release from the McHenry County Department of Health.

Individuals can protect themselves while outdoors by wearing protective clothing like light-colored, long-sleeved shirts, socks and pants. Health officials also encourage the emptying of standing water in containers like rimless tires, abandoned swimming pools, buckets, bird baths and clogged gutters, and ensuring doors and windows have tight-fitting screens.

Officials also recommend using EPA-registered insect repellents with one of the following active ingredients:

Most people exposed to the virus do not develop symptoms, but those who do typically experience illness between 2-14 days following the bite of an infected Culex mosquito.

Symptoms can include fever, headaches, body aches, joint pains, vomiting or a rash. Some more severe, and rarer, symptoms include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. Individuals over 50 years old or with serious underlying health conditions are at increased risk for developing severe symptoms.