The Lake County Health Department announced Wednesday that they have identified the first human case of West Nile virus in Lake County in 2025.
Lake County Health Department Public Information Officer Emily Young said the case was found in a Lake County resident, who is in their 70s.
The resident became ill in early July, Young said.
The Illinois Department of Public Health reported on June 24 that the first human case of West Nile virus in Illinois for the year was a Wayne County resident in southern Illinois who required hospitalization.
“Our time spent outdoors typically increases during the summer months, which also increases our exposure to mosquitoes,” Lake County Health Department Executive Director Chris Hoff said.
“Remember to take steps to protect yourself and your family from mosquitoes to reduce your risk of getting West Nile virus,” Hoff said.
Nine pools or batches of mosquitoes out of 214 have tested positive for West Nile virus this year in Lake County.
West Nile virus typically peaks during the late summer, usually from July through September, when the mosquito population is at its peak.
In August, a Lake County resident in their 80s died from West Nile virus. No deaths from the virus have been reported in Illinois in 2025.
The health department recommends residents follow the “4 Ds of Defense” to protect themselves from mosquitoes.
“Drain” standing water from items around your home, yard, and business.
“Defend” by using an insect repellent containing DEET, picaridin, oil of lemon eucalyptus, 2-undecanone, or IR3535 and reapply according to label directions.
“Dawn to Dusk” protect yourself all day and night and wear repellent outdoors during prime times for mosquito activity.
“Dress” in long sleeves, pants, and closed-toe shoes when outdoors to cover your skin.
Most people infected with West Nile virus have no symptoms of illness. However, some may become ill typically 3-15 days after the bite of an infected mosquito.
Common symptoms include fever, nausea, headache and muscle aches. In some individuals, severe illness including meningitis or encephalitis, or even death, can occur.
People older than 60 years and individuals with weakened immune systems are at higher risk for severe illness from West Nile virus, health officials said.
Residents can call the Lake County Health Department’s West Nile hotline to report areas of stagnant water, locations of dead birds and to obtain more information on the signs and symptoms of West Nile virus.
The West Nile hotline number is 847-377-8300.