Six horses in Northwestern Wisconsin have tested positive for eastern equine encephalitis (EEE), according to the Wisconsin Department of Health Services.

The health department is encouraging everyone to protect themselves from mosquito bites, as the virus can be spread to humans and other animals by infected mosquitoes.

EEE is very rare in Wisconsin, with only three human cases reported in the state since 1964. The most recent was in 2019, according to department spokesperson Jennifer Miller. Infection can be severe, however.

Many people infected with EEE virus do not get sick. Those who do become ill may develop encephalitis, an inflammation of the brain that typically begins with the sudden development of fever, headache, chills and vomiting. The illness may become severe resulting in disorientation, seizures, coma or death. There is no specific treatment for EEE illness, and death occurs in approximately 30% of people who develop encephalitis from the virus, according to the health department.

Mosquitoes acquire EEE virus by feeding on infected birds and can pass it on to humans and animals. It cannot be spread person to person or directly between humans and animals. No cases in humans have been reported this year. The fact that six horses have confirmed cases of EEE confirms there are mosquitoes in the area infected with the virus.

Newsletter signup for email alerts

The cases were reported in Chippewa, Dunn and Pepin counties, Miller said, but the department is raising the alarm statewide.

"We want everyone across the state to take precautions against mosquito bites to prevent not only encephalitis but West Nile Virus and the other things they can carry," Miller said.

To prevent mosquito bites, people are urged to limit the time they spend outside at dawn and dusk when mosquitoes are most active, apply insect repellent on exposed skin, ensure window and door screens are intact and prevent mosquitoes from breeding by removing stagnant water from items around their property.