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West Nile Virus Confirmed in Horse in Dunn County

DHS urges Wisconsinites to protect themselves against mosquito bites

The Wisconsin Department of Health Services (DHS) has confirmed that a horse in Dunn County, Wisconsin, has tested positive for West Nile virus. The positive test is a sign that mosquitoes infected with West Nile virus are present in Wisconsin and can transmit the virus to people and other animals.

The horse is the first reported West Nile virus infection in the state this year. Currently, no human cases of West Nile virus have been reported in 2023. DHS has monitored the spread of West Nile virus since 2001. An average of 17 cases of West Nile virus are reported among Wisconsin residents each year. West Nile virus infections in humans have been reported from June through October; however, most people with West Nile virus report becoming ill in August and September.

“The positive test in an animal is an important reminder to take steps to protect yourself from mosquito bites and potential disease,” said State Health Officer Paula Tran. “I urge Wisconsinites to continue to “fight the bite” and follow our tips to avoid illnesses spread by mosquitoes. This should include applying bug spray before they head outside and removing standing water in bird baths and other places around their homes to eliminate mosquito breeding sites.”

West Nile virus is spread to humans, horses, birds, and other animals through the bite of an infected mosquito. Mosquitoes acquire West Nile virus by feeding on infected birds. The virus is not spread directly from person to person, animal to animal, or animal to person.

Most people (80%) who are infected with West Nile virus do not get sick. Those who do become ill usually experience mild symptoms such as fever, headache, muscle ache, rash, and fatigue. However, some people (less than 1%) who become infected with the virus get seriously ill with symptoms that include high fever, muscle weakness, stiff neck, disorientation, mental confusion, tremors, confusion, paralysis, and coma. Older adults and those with compromised immune systems are at greater risk of developing severe illness that can be fatal. It is important that people contact a health care provider if they suspect they have West Nile virus illness.

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 West Nile virus 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).

DHS offers these tips to protect yourself and your family against mosquito bites:

Avoid mosquito bites by:

  • Appling an insect repellent with DEET, picaridin, oil of lemon eucalyptus, or IR3535 to exposed skin and clothing.

  • Treating clothing with permethrin before heading outdoors. You should not apply permethrin directly to your skin.

  • Considering rescheduling outdoor activities that occur during evening or early morning hours, when mosquitoes that spread West Nile virus are most active.

  • Wearing long-sleeves, long pants, and socks when outdoors to help keep mosquitoes away from your skin.

Mosquito-proof your home by:

  • Preventing mosquitoes from breeding around your home by removing stagnant water from items around your property.

  • Emptying standing water that has collected in tin cans, plastic containers, flowerpots, discarded tires, roof gutters, and downspouts.

  • Turning over wheelbarrows, kiddie pools, buckets, and small boats such as canoes and kayaks when not in use.

  • Changing the water in bird baths and pet dishes at least every three days.

  • Cleaning and chlorinating swimming pools, outdoor saunas, and hot tubs; drain water from pool covers.

  • Making sure window and door screens are intact and tightly fitted to prevent mosquitoes from getting into your home.

  • Trimming or mowing tall grass, weeds, and vines since mosquitoes use these areas to rest during hot daylight hours.

Media release from the Wisconsin Department of Health and Human Services.


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