West Nile virus detected in Genoa mosquitoes

Mosquitoes collected in Genoa city limits have tested positive for West Nile virus, according to the DeKalb County Health Department.

West Nile virus also was identified in mosquitoes in DeKalb over the past week, while in July, traps in Sycamore showed West Nile present in mosquitoes, according to the release.

As of Tuesday, four mosquito traps in DeKalb County have collected mosquitoes that tested positive for West Nile virus this year, according to the release. No known human cases have been reported in the county in 2025, however.

West Nile virus, which usually results in mild symptoms but also can cause serious illness, is transmitted through bites from infected mosquitoes, according to the DeKalb County Health Department. About 20% of people who become infected with the virus develop a fever and other symptoms, while about 1 out of 150 infected people develop a serious, sometimes fatal illness, according to the U.S. Centers for Disease Control and Prevention.

While DeKalb County health officials report that most people infected with West Nile virus have no clinical symptoms, those who do will become ill between three and 14 days after being bitten by an infected mosquito.

Mild cases of West Nile virus can include fever, headache and body aches. More serious cases can cause encephalitis and meningitis to develop, health officials said.

There are no West Nile virus vaccines that are licensed for use in humans, according to the CDC. Although local officials said most mosquitoes don’t carry West Nile virus, they also said the most effective way to prevent a viral infection is to reduce the chances of being bitten by mosquitoes.

Tips to stay healthy and safe

• Avoid being outdoors when mosquitoes are most active, especially between dusk and dawn.
• When outdoors, wear shoes and socks, long pants and a long-sleeved shirt, and apply insect repellent that includes DEET, picaridin or oil of lemon eucalyptus according to label instructions. Consult a physician before using repellents on infants.
• Make sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or other openings. Try to keep doors and windows shut, especially at night.
• Change water in birdbaths weekly. Properly maintain wading pools and stock ornamental ponds with fish. Turn over any buckets, garbage cans or other containers that collect water.

For more information, visit the DeKalb County Health Department website at health.dekalbcounty.org