Mosquitoes test positive for West Nile virus in Lake County

WAUKEGAN — A mosquito “pool” (batch of mosquitoes) sampled on June 24 at a Southlake Mosquito Abatement District trap in Highland Park has tested positive for West Nile virus.

This mosquito pool is the first confirmed indicator of West Nile virus presence in Lake County in 2025.

“Mosquitoes are an expected part of summer, but they also carry diseases that can lead to serious illness and even death,” Chris Hoff, executive director of the Lake County Health Department and Community Health Center, said in a news release. “We can take steps to ‘Fight the Bite’ to protect ourselves and our families while we enjoy all that summer has to offer.”

Practice the “4 Ds of Defense” to protect yourself and your family from mosquitoes:

Drain: Drain standing water from items around your home, yard and business.

Defend: When outdoors, use an insect repellent containing DEET, picaridin, oil of lemon eucalyptus, 2-undecanone, or IR3535 and reapply according to label directions.

Dawn and Dusk: Protect yourself all day and night, and wear repellent outdoors during these prime times for mosquito activity.

Dress: Wear long sleeves, pants, and closed toe shoes when outdoors to cover your skin.

Culex pipiens mosquitoes are the primary carriers of West Nile virus. Residents can help prevent these mosquitoes from breeding by eliminating areas of stagnant water from their properties. Items like buckets, gutters and plant containers, kiddie pools, and any other items holding water around homes and businesses can become breeding sites.

The Lake County Health Department’s Mosquito Surveillance Program coordinates mosquito trapping results throughout Lake County. Mosquitoes are tested weekly for West Nile virus. The program also monitors reports of dead birds (an early sign of the presence of the virus) and investigates areas of stagnant water for the presence of mosquito larvae, specifically from the Culex mosquito, which is the primary carrier of West Nile in Illinois.

“With the warmer weather, people spend more time outdoors and mosquitoes become active,” Alana Bartolai, ecological services program coordinator at the Health Department, said in the release. “From late spring to fall, we set traps around Lake County and monitor weekly for this public health threat.”

In 2024, 154 out of 723 mosquito pools tested positive for West Nile virus. There were six human cases of West Nile virus. Since 2002, there have been 86 confirmed human cases of West Nile virus in Lake County, as well as five confirmed deaths.

Most people infected with West Nile virus have no symptoms of illness. However, some may become ill usually three to 15 days after the bite of an infected mosquito. Common symptoms include fever, nausea, headache and muscle ache. In some individuals, severe illness including meningitis or encephalitis, or even death, can occur. People older than 50 and individuals with weakened immune systems are at higher risk for severe illness from West Nile virus.

Find more prevention tips and information on West Nile virus at www.FightTheBiteNow.com. Residents can also call the Health Department’s West Nile hotline to report areas of stagnant water, report locations of dead birds, and obtain more information on the signs and symptoms of West Nile virus. The West Nile hotline number is 847- 377-8300.