Michigan confirms second horse with Eastern equine encephalitis in 2026

Michigan's second case of Eastern equine encephalitis (EEE) in a domestic animal in 2026 has been detected in a horse in Roscommon County.   

State health officials said the mosquito-borne illness was found in an 18-month-old quarter horse filly. 

The filly was humanely euthanized, according to officials. 

The human case of EEE was also found in a Roscommon County resident earlier this summer. It's the first human case in Michigan since 2021. 

"EEE and other mosquito-borne diseases are preventable. By working with your veterinarian to be sure your animals are fully vaccinated, you can protect them from these viruses. This is Michigan's second case this summer and underscores the importance of vaccinations and mosquito control," said State Veterinarian Dr. Nora Wineland, DVM, MS, DACVPM. "These detections show that EEE, along with other mosquito-borne viruses, is present in the state's mosquito population. Taking steps to avoid mosquito bites is essential to reducing the risk of these diseases for both animals and people."

The state's first case of EEE detected in a domestic animal this year was found in an under-vaccinated quarter horse colt in Clare County in late August. 

Like other mosquito-borne illnesses, Michigan health officials say EEE cannot be passed by horse-to-horse or horse-to-human contact. Cases are typically seen in the state's late summer and early fall. 

How you can protect animals from mosquito-borne illnesses

• Talk to a veterinarian about vaccinating horses against EEE, WNV, and other mosquito-borne diseases.
• Eliminate standing water—i.e., fill in puddles, repair eaves, and change the water in buckets and bowls at least once a day.
• Place livestock in a barn under fans (as mosquitoes are not strong flyers) and pets inside the home during peak mosquito activity from dusk to dawn.
• Use an insect repellent on animals that is approved for the species.
• Contact a veterinarian if an animal shows signs of illness. If a Michigan animal is suspected of having EEE or WNV, funding is available under an arbovirus grant to cover these testing costs. 

How you can protect yourself against mosquito-borne diseases

MDARD recommends the following tips to protect you and your family from mosquito-borne illnesses like EEE.

• Apply insect repellents that contain the active ingredient DEET or other EPA-approved products to exposed skin or clothing. Always follow the manufacturer's directions for use.
• Wear light-colored, long-sleeved shirts and long pants when outdoors. Apply insect repellent to clothing to help prevent bites.
• Maintain window and door screening to help keep mosquitoes outside.
• Empty water from mosquito breeding sites around the home, such as buckets, unused kiddie pools, old tires, and other water-holding containers where mosquitoes can lay eggs.