Mosquitoes trapped in Hamilton County tested positive for West Nile virus, the first detection of the season, but no human infections have been confirmed.
Hamilton County Public Health announced Aug. 26 that mosquitoes collected in Green Township on July 30 carried the virus. The Ohio Department of Health confirmed the results after routine testing.
Sharonville, Evendale and Woodlawn residents fall under HCPH's jurisdiction, meaning the agency's response and guidance cover those communities. HCPH serves all of Hamilton County except Cincinnati, Springdale and Norwood. Springdale residents fall under the City of Springdale Health Department, which has not issued a separate West Nile announcement.
No one in Hamilton County has tested positive for West Nile virus in 2026, according to the agency. The virus was found only in trapped mosquitoes.
What HCPH is doing
After the detection, HCPH environmental health specialists began surveilling the area and treating standing water with larvicide to prevent further mosquito breeding. Staff also distributed educational materials to nearby residents.
How residents can protect themselves
HCPH promotes a three-step approach it calls "drain, dunk, protect":
- Drain standing water from pools, birdbaths, toys, open containers, wheelbarrows, old tires and gutters.
- Dunk larvicide tablets into water that cannot be drained to kill mosquito larvae.
- Protect yourself by avoiding the outdoors at dusk and dawn, wearing light-colored loose-fitting clothing and applying EPA-registered mosquito repellent.
Peak biting times are dusk and dawn, particularly in humid or wooded areas.
Symptoms to watch for
West Nile virus affects the central nervous system and spreads through infected mosquito bites. Mild cases produce fever, headaches, body aches, joint pain, vomiting, diarrhea or rash. Most people recover fully, though fatigue can linger for weeks or months.
Severe illness can include meningitis, encephalitis and acute flaccid myelitis. Anyone experiencing severe symptoms should see a doctor immediately.
Reporting mosquito problems
Residents who notice heavy mosquito activity or standing water on abandoned properties or in neglected pools can file a complaint online at hamiltoncountyhealth.org, and HCPH's environmental health team will investigate.
