Two Animals Test Positive for West Nile Virus in Wisconsin

The Wisconsin Department of Health Services (DHS) is reminding people to protect themselves from mosquito bites now that two animals in the state have tested positive for West Nile virus (WNV). A bird from Milwaukee County and a horse from Trempealeau County are the first reported WNV infections in the state this year. No human cases of WNV have been reported yet in 2022. The presence of animals with WNV confirms that there are mosquitoes infected with WNV in the state that can transmit the virus to people and other animals.

"These cases are a reminder of the importance of taking precautions to protect ourselves from mosquitoes and the viruses they carry, which poses a risk to all Wisconsinites, especially to those who have weakened immune systems," said State Health Officer Paula Tran. “By wearing insect repellent and eliminating standing water around our homes where mosquitos breed, we can help protect ourselves and our neighbors.” 

WNV is spread to humans, horses, birds, and other animals through the bite of an infected mosquito. Mosquitoes acquire WNV 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 WNV 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 WNV illness. For those without a provider, help is available by dialing 211 or 877-947-2211, or texting your ZIP code to 898-211 for free, confidential support.

DHS has monitored the spread of WNV since 2001. An average of 20 cases of WNV were reported among Wisconsin residents each year during the period from 2017 – 2021. WNV infections in humans have been reported from June through October; however, most people with WNV reported 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 for at least four consecutive hours). 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

• 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.

To learn more about WNV and other diseases that can be spread by mosquitoes and how to protect yourself, visit the DHS website.