Eastern Equine Encephalitis (EEE) Virus

What is Eastern Equine Encephalitis (EEE)?

EEE virus is a rare cause of brain infections (encephalitis). Only a few cases are reported in the United States each year. Most occur in eastern or Gulf Coast states. Approximately 30% of people with EEE die and many survivors have ongoing neurologic problems. EEE virus is transmitted through the bite of an infected mosquito. Disease transmission does not occur directly from person to person.



Preventing mosquito bites is the best prevention against EEE. 

  • Use insect repellent containing DEET, picaridin, IR3535, or oil of lemon eucalyptus on exposed skin and/or clothing. The repellent/insecticide permethrin can be used on clothing to protect through several washes. Always follow the directions on the package.
  • Wear long sleeves and pants when weather permits.
  • Have secure, intact screens on windows and doors to keep mosquitoes out.
  • Eliminate mosquito breeding sites by emptying standing water from flowerpots, buckets, barrels, and other containers. Drill holes in tire swings so water drains out. Keep children’s wading pools empty and on their sides when they aren’t being used.


Information from the Michigan Department of Health and Human Services (MDHHS) regarding the
2019 EEE Outbreak in Michigan

EEE Information from the CDC

Frequently Asked Questions

How many total cases of EEE are there in Michigan?

As of October 9, 2019, there have been 10 human cases, 4 of which were fatal, and 39 animal cases. To see current updates on the number of human and animal cases of EEE and other arboviral diseases, visit www.Michigan.gov/EEE. Look for the infographic posted at the “Weekly Summary: Arbovirus activity, including Eastern Equine Encephalitis in Michigan” section.

Why are we seeing EEE cases in Michigan?

Michigan has had outbreaks of EEE about every decade since 1980 when the first human case was reported in the state. This year, the number of EEE cases is significantly higher than in previous years. In fact, Michigan has seen the same number of EEE cases in this one year as the last ten years combined. It is unknown exactly why some years are more severe than others, although weather, including temperature and rainfall, is thought to play a role.

How do people get infected with EEE?

EEE is transmitted through the bite of an infected mosquito. You can not get EEE directly from another person or from an animal such as a horse or deer.  

Who is at risk for infection with EEE?

Anyone in an area where the virus is circulating in mosquitoes can get infected with EEE. The risk is highest for people who live in or visit woodland habitats, and people who work outside or participate in outdoor recreational activities, because of greater exposure to potentially infected mosquitoes. Those who are over 50 years old and under 15 years old are at increased risk of infection.

How soon do people get sick after getting bitten by an infected mosquito?

It takes 4 to 10 days after the bite of an infected mosquito to develop symptoms of EEE.  What are the symptoms of EEE disease?  Severe cases of EEE infection begin with the sudden onset of headache, high fever, chills, and vomiting.  The illness may then progress into disorientation, seizures, and coma. Approximately a third of patients who develop EEE die, and many of those who survive have mild to severe brain damage.

How do I get tested for EEE?

People who have been bitten by mosquitoes can monitor their health and talk with their healthcare provider if they develop symptoms such as fever, malaise, headache, and confusion. Testing for EEE is not indicated in a person who is not showing signs suggestive of EEE illness.

How is EEE diagnosed?

Diagnosis is based on tests of blood or spinal fluid. These tests typically look for antibodies that the body makes against the viral infection.

What is the treatment for EEE?

There is no specific treatment for EEE. Antibiotics are not effective against viruses, and no effective antiviral drugs have been discovered. Severe illnesses are treated by supportive therapy which may include hospitalization, respiratory support, IV fluids, and prevention of other infections.

How can people reduce the chance of getting infected with EEE?

  • Avoid being outdoors between dusk and dawn when mosquitoes that carry the EEE virus are most active.
  • Apply insect repellents that contain the active ingredient DEET, or other U.S. Environmental Protection Agency-registered product 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 kiddie pools, old tires, or similar sites where mosquitoes may lay eggs.
  • Use nets and/or fans over outdoor eating areas.

Can I get sick from eating deer meat if it is infected with EEE?

If an animal appears ill, you should not consume the meat from that animal, as there are other illnesses that can be transmitted. To kill potential pathogens, the wild game should always be thoroughly cooked to an internal temperature of 165 degrees F, measured with a meat thermometer.

Can my pet get EEE?

EEE is rare in dogs and cats, however, when cases have been identified in dogs, they’re typically less than six months old. Horses are very susceptible to EEE and approximately 90 percent of horses that show signs of EEE die from the disease. A vaccine is available for horses.

How do I protect my pets from EEE?

Keep pets indoors as much as possible between dusk and dawn, when mosquitoes are most active.  Mosquito repellents labeled for use on people should not be used on pets. There are some topical products that can be applied to dogs to protect them from mosquitoes; concerned pet owners should work with their veterinarians.