Image description: A close-up of a mosquito biting a human.
Hamilton County Public Health (HCPH) has confirmed the jurisdiction’s first human case of West Nile virus of 2026 in the Symmes Township area. Officials say a mosquito carrying the virus likely bit the individual. Download our fact sheet to learn how to protect yourself from mosquito bites and reduce your risk of West Nile virus.
How did HCPH confirm a case of West Nile virus in Hamilton County?
HCPH was notified of the suspected case on Sept. 17 and received confirmation later that day. Since then, HCPH has since been consulting with the medical providers and health agencies involved in the case. HCPH also has reviewed the patient’s medical records and recent activities to assess whether the infection was locally acquired or associated with travel.
Earlier this summer, HCPH had shared information with the public and the media about mosquitoes that were confirmed as positive for carrying West Nile virus within our jurisdiction (all of Hamilton County except for Cincinnati, Norwood and Springdale). That mosquito pool was collected through HCPH’s trapping program on July 30 in Green Township and confirmed by ODH on Aug. 26. At that time, there were no human cases of West Nile virus within HCPH’s jurisdiction.
What is West Nile virus?
West Nile virus is a disease that affects the central nervous system and commonly is spread to humans through the bite of an infected mosquito, particularly during mosquito season. The virus is not contagious.
People with mild cases of West Nile virus infection typically experience flu-like symptoms such as fever, headaches, body aches, joint pain, vomiting, diarrhea or rash. Most people with mild illness recover completely, but fatigue and weakness can last for weeks or months.
Most people who are bitten by an infected mosquito will not become sick. However, people with additional health issues – such as a weakened immune system, chronic medical conditions or advanced age – are at risk for severe illness or even death. People who experience severe symptoms should see a doctor as soon as possible. There is no treatment for West Nile virus.
How can you reduce your risk of getting West Nile virus?
Mosquito season in Ohio typically runs through October, and the insects typically remain active until temperatures drop below 50°F or after the first frost in Hamilton County. But both at home and during travel, Hamilton County residents can help reduce the risk of West Nile virus and other mosquito-borne diseases for themselves and for others:
Drain, dunk, protect: his phrase can help property owners reduce the number of mosquitoes hanging around.
- Drain: Eliminate standing water that collects in pools, birdbaths, toys and playsets, open containers, wheelbarrows, old tires, gutters and other vessels.
- Dunk: Use larvicide or “dunks” to kill mosquito larvae in standing water that cannot be drained.
- Protect: Avoid being outdoors during peak mosquito times (dusk and dawn), especially in humid or wooded spaces. Wear light-colored, loose-fitting clothing, and apply mosquito repellants to your skin according to product instructions.
Review international travel warnings: CDC’s Travelers’ Health webpage features important health notices and provides geographically relevant information on mosquito-borne diseases and other health concerns.
Speak with your healthcare provider: Ask about recommended or required vaccines for international travel.
Be prepared: When heading to an area with an elevated risk for mosquito-borne diseases, bring EPA-registered mosquito repellents, protective clothing and mosquito netting.
Get the facts: Download HCPH’s fact sheets for more tips.
Published on 10/5/2026