Cases of Eastern Equine Encephalitis in 2020 are Outpacing Those from 2019

Horse owners are urged to vaccinate their animals

For immediate release: September 9, 2020

Media contacts:
     MDARD: Jessy Sielski, 517-331-1151
     MDHHS: Lynn Sutfin, 517-241-2112

LANSING, Mich.— With the recent discovery of five additional cases of Eastern Equine Encephalitis (EEE) in equids over the holiday weekend, the number of confirmed cases for 2020 is more than double the number of cases found by this time last year. This rise in cases intensifies the need for horse owners to vaccinate their animals and for Michigan residents to take precautions.

EEE is one of the most dangerous mosquito-borne diseases in the U.S. that can affect both animals and humans. In 2019, Michigan experienced one of the worst outbreaks of EEE ever documented in the state, with 10 human cases — including 6 deaths — and 50 cases in animals from 20 counties.

While the first case of EEE in 2019 was reported about two weeks earlier than the first case for this year, only eight cases of the disease were confirmed in horses at this point of the year in 2019. Currently, for 2020, the Michigan Department of Agriculture and Rural Development (MDARD) has confirmed 18 cases in equids.

Additionally, in 2019, the cases were found across only three counties: Barry (2), Kalamazoo (3), and St. Joseph (3). This year, cases have been discovered in eight counties: Barry (1), Clare (5), Isabella (1), Kent (1), Mecosta (1), Montcalm (6), Newaygo (2), and Oakland (1). 

“We cannot state this strongly enough: horse owners and the general public need to take responsible, proactive steps to protect themselves and their animals from mosquito-borne diseases immediately,” said State Veterinarian Nora Wineland, DVM. “We don’t know if the dramatic increase in EEE equid cases is due to a lapse in vaccinations or a higher prevalence of EEE in Michigan’s mosquito population, but it doesn’t matter. If we ignore what’s happening, we run the risk of losing lives.”

Even though the state is experiencing some cooler temperatures, this should not cause horse owners or residents to ease up on the precautions that they are taking. The virus is typically seen in late summer to early fall each year in Michigan. Typically, mosquito-borne illnesses, like EEE, will continue to pose a risk to both animals and humans until about mid-October after there have been at least two hard frosts.

“We strongly urge Michiganders to take precautions against mosquito bites,” said Dr. Joneigh Khaldun, chief medical executive and chief deputy for health at the Michigan Department of Health and Human Services. “Mosquito-borne diseases can cause long-term health effects in people, even death. Signs of EEE include the sudden onset of fever, chills, body and joint aches. Severe encephalitis, resulting in headache, disorientation, tremors, seizures and paralysis and even death can also occur.”

To protect your horses and other domestic animals (such as dogs, sheep, and goats), measures could include the following:  

  • Talking to a veterinarian about vaccinating horses against EEE.
  • Placing livestock in a barn under fans (as mosquitos are not strong flyers) during peak mosquito activity from dusk to dawn.
  • Using an insect repellant on an animal that is approved for the species.
  • Eliminating 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.
  • Contacting a veterinarian if an animal shows signs of the illness: fever and stumbling, which can progress to being down and struggling to stand.

To protect yourself and your family, here’s what you should do now:

  • Apply insect repellents that contain the active ingredient DEET, or other U.S. Environmental Protection Agency-approved products, to exposed skin or clothing and always follow the manufacturer’s directions for use.
  • Wear 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 children’s pools, old tires, or similar sites where mosquitoes may lay eggs.
  • Use nets and/or fans over outdoor eating areas.

For more information about mosquito-borne diseases, visit