Lake County has reported its first human case of the year of neuroinvasive West Nile virus, with a resident in their 70s becoming ill earlier this month.
An update on the victim’s condition was not released. This is the second case of the virus in Illinois reported this year. Last year saw 69 cases across the state, including six in Lake County, according to data from the Illinois Department of Public Health.
Lake County Health Department and Community Health Center Executive Director Chris Hoff advised caution for residents spending more time outdoors during the summer, exposing themselves to mosquitoes, which can carry the virus.
“Remember to take steps to protect yourself and your family from mosquitoes to reduce your risk of getting West Nile virus,” Hoff said.
According to a county release, nine of 214 batches of mosquitoes have tested positive for West Nile virus in 2025. West Nile virus typically peaks during the late summer, usually from July through September when the mosquito population is at its peak, the release said.
The department gave “4 Ds of Defense” for protecting against mosquitoes — drain, defend, dawn to dusk and dress. These include draining any standing water, using EPA-approved insect repellents, using proper protection during prime mosquito activity hours and wearing clothes that cover exposed skin.
According to the release, most people infected with West Nile virus have no symptoms, but some become ill three to 15 days after being bitten by an infected mosquito. Symptoms include fever, nausea, headache and muscle aches.
In rare cases, the virus can affect the brain or spinal cord, leading to “serious neurological symptoms” such as stiff neck, confusion, sudden weakness or numbness on one side of the body, trouble walking or even death.
Those over 60 and individuals with weakened immune systems or multiple medical conditions are at higher risk for severe illness from West Nile virus.
