First Human Case of West Nile Virus Confirmed in Wisconsin 

The Wisconsin Department of Health Services (DHS) and Public Health Madison & Dane County have confirmed the first human case of West Nile virus in a Wisconsin resident this year. The individual is a resident of Dane County. Cases of West Nile virus have also been reported in three horses in Wisconsin and several mosquito pools. The horse cases were located in Dunn and Clark counties, and the positive mosquitoes were from Milwaukee and Lafayette counties.

“This confirmed case in a Wisconsin resident is a reminder that even as summer winds down, we still need to take precautions to prevent mosquito bites. While West Nile virus and other viruses spread by mosquitoes pose a risk to all Wisconsinites, people who have weakened immune systems are at the greatest risk for serious illness,” said State Health Officer Paula Tran.

Since West Nile virus was first detected in Wisconsin in 2002, infections in humans have been reported from June through October. 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 risk of West Nile virus infection continues until the first hard frost.

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. 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 West Nile virus are most active.
  • Wear long-sleeves, long pants, and socks when outdoors to help keep mosquitoes away from your skin.

Mosquito-Proof Your Home

  • Make sure window and door screens are intact and tightly-fitted to prevent mosquitoes from getting into your home.
  • Prevent mosquitoes from breeding around your home by removing stagnant water from items around your property, such as 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.
  • Trim or mow tall grass, weeds, and vines since mosquitoes use these areas to rest during hot daylight hours.