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MDARD Confirms Eastern Equine Encephalitis in St. Joseph County Horse

  Take precautions to protect your animals, yourself, and your family

LANSING, Mich.—Today, the Michigan Department of Agriculture and Rural Development is reporting Michigan’s first case of Eastern Equine Encephalitis (EEE) for 2022 in a three-year-old Standardbred filly from St. Joseph County. This discovery underscores the need for both horse owners and Michigan residents to take precautions.

EEE is a zoonotic, viral disease transmitted by mosquitoes to both animals and people; it is typically seen in late summer to early fall each year in Michigan. EEE is one of the most dangerous mosquito-borne diseases in the U.S. with a 90 percent fatality rate among horses that become ill and a 33 percent fatality rate among humans who become ill. Last year, Michigan experienced 9 cases of EEE in horses and one human case.

“The St. Joseph County horse was never vaccinated against EEE, and it developed signs of illness—including fever and ataxia—which progressed to the animal exhibiting neurologic signs and being down on the ground with an inability to get up. The horse later succumbed to the disease,” said State Veterinarian Nora Wineland, DVM. “It is critically important for horse owners to reach out to their veterinarian to discuss how to best protect their animals from EEE and other mosquito-borne diseases.”

To protect horses and other animals, owners are encouraged to take the following precautions: 

Talk to a veterinarian about vaccinating horses against EEE and other mosquito-borne diseases.
Place livestock in a barn under fans (as mosquitoes are not strong flyers) during peak mosquito activity from dusk to dawn.
Use an insect repellant on animals that is approved for the species.
Eliminate standing water on the property—i.e., fill in puddles, repair eaves, and change the water in buckets and bowls at least once a day.
Contact a veterinarian if a horse shows signs of the illness: mild fever and stumbling, which can progress to being down and struggling to stand.

People can also be infected with EEE from the bite of a mosquito carrying the virus. The disease is not spread by horse-to-horse or horse-to-human contact. In humans, signs of EEE include the sudden onset of fever, chills, and body and joint aches. The virus can also cause severe encephalitis, resulting in headaches, disorientation, tremors, seizures, and paralysis. Permanent brain damage, coma, and death may occur in some cases.

"This equine case indicates the EEE virus is here in Michigan and provides a warning that residents could also become infected by a mosquito," said Dr. Natasha Bagdasarian, Michigan Department of Health and Human Services chief medical executive. "Michigan residents are urged to take precautions and protect themselves from mosquito bites."

Michiganders can stay healthy by following steps to avoid mosquito bites:

Using EPA registered insect repellents with one of the following active ingredients: DEET, picaridin, IR3535, oil of lemon eucalyptus or para-menthane-diol, and 2-undecanone; follow the product label instructions and reapply as directed.
o Don’t use repellent on children under 2 months of age. Instead, dress your child in clothing that covers arms and legs and cover crib, stroller and baby carrier with mosquito netting.
Wearing shoes and socks, light-colored long pants and long-sleeved shirts when outdoors.
Making sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or other openings.
Using bed nets when sleeping outdoors or in conditions with no window screens.
Eliminating all sources of standing water that can support mosquito breeding around your home, including water in bird baths, abandoned swimming pools, wading pools, old tires and any other object holding water once a week.
Overall, EEE and other mosquito-borne illnesses will continue to pose a risk to both animals and humans until temperatures consistently fall below freezing.

For more information about EEE, please visit