Wisconsin health officials are again warning of the dangers of mosquito-borne diseases after detecting the first West Nile virus activity in the state for 2025, on the eve of its normal peak season.

A human case of WNV illness has been reported in a Barron County resident in northwestern Wisconsin, and mosquitos collected from Milwaukee and Lafayette counties — both well downstate — have tested positive for WNV.

“The first detections of West Nile virus this year are a reminder to take steps to prevent mosquito bites and possible disease. West Nile virus poses a risk to all Wisconsinites, but people who have weakened immune systems are at higher risk for serious illness,” Paula Tran, state health officer and administrator of the DHS Division of Public Health, said in a news release.

WNV is spread to humans, birds and other animals through the bite of an infected mosquito. Mosquitoes get 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 who are infected with WNV do not have symptoms. Those who become ill with WNV may experience fever, chills, headache, muscle aches, rash and fatigue. Some people will develop severe illness, with symptoms that include high fever, muscle weakness, stiff neck, disorientation, mental confusion, tremors, paralysis, seizure and coma. Older adults and people who have 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, the DHS advises.

DHS has monitored WNV since 2001, tracking confirmed cases in mosquitoes, animals, and humans across the state in order to alert health care providers and residents about risk. An average of 18 cases of WNV illness are reported in Wisconsin each year. WNV cases in humans have been reported from June through November; 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 them 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.

The Department of Health Services offers these tips to protect against mosquito bites —

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

— Before heading outdoors, treat clothing with permethrin but 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 skin.

Mosquito-proof your home —

— Prevent mosquitoes from breeding around the home by removing stagnant water around the 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 the home’s window and door screens are intact and tightly fitted to prevent mosquitoes from getting inside.

— Trim or mow tall grass, weeds and vines, since mosquitoes use these areas to rest during hot daylight hours.

For more information, go to the DHS websites, https://www.dhs.wisconsin.gov/mosquito/wnv.htm and https://www.dhs.wisconsin.gov/fight-bite/index.htm.