Mosquitoes trapped in Green Township tested positive for West Nile virus, Hamilton County Public Health announced Aug. 28 marking the first detection of the virus in the county this year.
No human cases have been reported.
HCPH's jurisdiction covers Hamilton County outside Cincinnati, Springdale and Norwood. The virus does not respect municipal boundaries, and the agency's prevention guidance applies equally to east-side neighborhoods including Hyde Park, Oakley and Mount Lookout.
What happened
Hamilton County Public Health trapped the mosquitoes in a residential area of Green Township on July 30. The Ohio Department of Health (ODH) tested the samples and confirmed the positive result on Aug. 26, according to the agency's announcement.
Starting Friday, Aug. 28, HCPH environmental health specialists plan to monitor the Green Township area, treat standing water with larvicide and speak with residents about mosquito concerns, Spectrum News 1 reported.
Context from 2025
Last year, Hamilton County recorded one human case of West Nile virus confirmed by the U.S. Centers for Disease Control and Prevention (CDC). Evidence pointed to a locally acquired infection, meaning the person was likely bitten by a mosquito in the area, according to WCPO.
Three mosquito samples tested positive in 2025: in Wyoming on July 7, in Anderson Township on July 22 and in Green Township on July 31.
How to protect your property
HCPH recommends the "Drain, dunk, protect" method:
- Drain standing water from pools, birdbaths, toys, wheelbarrows, old tires, gutters and open containers.
- Dunk larvicide tablets into standing water that cannot be drained.
- Protect yourself by avoiding outdoor activity at dusk and dawn, wearing light-colored loose-fitting clothing and applying mosquito repellent according to product instructions.
Symptoms to watch for
West Nile virus affects the central nervous system. Mild cases produce flu-like symptoms: fever, headaches, body aches, joint pain, vomiting, diarrhea or rash. Most people recover completely, though fatigue can linger for weeks.
Severe cases can cause meningitis, encephalitis or acute flaccid myelitis. Anyone experiencing severe symptoms should see a doctor immediately.
Reporting standing water
Residents who notice high mosquito activity or standing water on an abandoned property or in a neglected pool can file a complaint online with HCPH's environmental health team for investigation.
