First Confirmed West Nile Virus Infection in Dunn County

Dunn County Health Department urges everyone to protect themselves against mosquito bites

Menomonie, WI, September 18, 2025 – The Dunn County Health Department reminds residents to protect themselves from mosquito bites and potential disease. The first human West Nile virus (WNV) infection has been confirmed in a healthy blood donor from Dunn County whose blood screened positive for WNV. The presence of a blood donor with WNV confirms that there are mosquitoes infected with WNV in the area that can spread the virus to other people and reported from June through October; however, most people with WNV report becoming ill in August and September.

The best way to avoid illnesses spread by mosquitoes is to reduce exposure to mosquitoes and eliminate mosquito breeding sites. Mosquito activity and the risk of WNV will continue through the rest of the summer until there is a hard frost (temperatures below 28 degrees Fahrenheit for at least four straight hours). Wisconsin Department of Health Services (DHS) offers these tips to protect yourself and your family against mosquito bites:

Avoid Mosquito Bites

• Apply an insect repellent with DEET, picaridin, oil of lemon eucalyptus, or IR3535 to exposed skin and clothing.
• Prior to heading outdoors, treat clothing with permethrin; do not apply permethrin directly to skin.
• Consider rescheduling outdoor activities that occur during evening or early morning hours, when mosquitoes that spread WNV are most active.
• Wear long-sleeves, long pants, and socks when outdoors to help keep mosquitoes away from your skin.

Mosquito-Proof Your Home

• Prevent mosquitoes from breeding around your home by removing stagnant water from items around your property.
  • Empty standing water that has collected in tin cans, plastic containers, flower pots, discarded tires, roof gutters, and downspouts.
  • Turn over wheelbarrows, kiddie pools, buckets, and small boats such as canoes and kayaks when not in use.
  • Change the water in bird baths and pet dishes at least every three days.
  • Clean and chlorinate swimming pools, outdoor saunas, and hot tubs; drain water from pool covers.
• Make sure window and door screens are intact and tightly-fitted to prevent mosquitoes from getting into your home.
• Trim or mow tall grass, weeds, and vines since mosquitoes use these areas to rest during hot daylight hours.

If you have questions about West Nile Virus, call the DCHD at 715-232-2388 or visit the Wisconsin DHS webpages on WNV at https://www.dhs.wisconsin.gov/mosquito/wnv.htm, https://www.dhs.wisconsin.gov/mosquito/wnv-data.htm and https://www.dhs.wisconsin.gov/mosquito/bite-prevention.htm