Mosquitoes Test Positive for
West Nile Virus in Defiance County

August 24, 2023

The Defiance County Health Department has been notified by the Ohio Department of Health that one mosquito sample pool collected in the county has tested positive for West Nile Virus.  The sample was collected on August 10, 2023.  Mosquitos that carry the West Nile Virus are common in Ohio in the summer and fall months. This is the first positive sample identified in Defiance County during the 2023 mosquito collection season. 

West Nile Virus is the leading cause of mosquito-borne disease in the United States and is spread to people by the bite of an infected northern house mosquito, Culex pipens.  About 20% of people who become infected with West Nile Virus will experience symptoms, which may include:

  • Fever
  • Headache
  • Body aches
  • Nausea
  • Vomiting
  • Swollen lymph glands
  • Rash on the chest, stomach, or back. 

Symptoms usually appear 2 to 14 days after a person is bitten by an infected mosquito and symptoms can last for a few days to as long as several weeks.  Less than 1% of infected people will develop severe illness.

The best way to avoid West Nile Virus is to prevent mosquito bites.  Mosquito bites can be prevented by avoiding areas where mosquitos are present, but if you need to be in these areas wear an EPA-approved mosquito repellent and wear loose long sleeve shirts and pants. 

The number of mosquitos can be reduced by removing sources of standing water where they breed. Common sources of household standing water include: old tires, plastic containers, pools, planters and pots, gutters & wheelbarrows.  Even very small amounts of water can be a breeding site for mosquitoes. 

For more information regarding West Nile Virus testing visit Ohio Department of Health’s website at for weekly updates.



Brian Heil, REHS
Health Promotion Coordinator

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