Visit www.Michigan.gov/EEE for information on EEE in Michigan, including updated case counts and aerial pesticide spraying information for counties with human or animal cases.

Eastern Equine Encephalitis (EEE) Virus Fact Sheet (PDF)

What is Eastern Equine Encephalitis (EEE) virus?

Eastern Equine Encephalitis (EEE) is a virus that can cause swelling of the brain (encephalitis). It is a mosquito-borne disease, meaning that it is spread by the bite of an infected mosquito.

How is EEE spread?

Mosquitoes become infected with EEE virus by biting birds that have the virus. EEE virus can be spread to some mammals, including humans and horses, by the bite of an infected mosquito. An infected human or horse cannot spread the virus to others.

Is EEE virus in Michigan?

EEE virus has been reported in animals and people throughout the state. EEE virus is most commonly found in swamp and bog habitats where human activity is limited, making human cases of EEE rare in Michigan. The risk of getting EEE virus is highest from late spring through early fall.

What is the treatment for EEE virus?

There is no specific treatment or medication for this infection. Patients with suspected EEE should contact their healthcare provider immediately for evaluation, testing, and supportive treatment.

What are the symptoms of EEE?

Most people who become infected with EEE virus do not develop symptoms. Symptoms of EEE typically occur 4 to 10 days after the mosquito bite and can include:

• Chills
• Fever
• Weakness
• Joint pain
• Body aches

Severe cases of EEE can result in encephalitis (swelling of the brain) or meningitis (infection of the membranes that surround the brain and spinal cord). Symptoms include:

• Headache
• Fever
• Vomiting
• Diarrhea
• Behavioral changes/irritability
• Drowsiness

The illness may then progress into disorientation, seizures, and coma. Approximately a third of people who develop encephalitis due to EEE die, and many of those who survive have mild to severe brain damage.

How can EEE virus be prevented?

The best way to prevent EEE infection is to prevent mosquitoes from biting you.

• Use Environmental Protection Agency (EPA)-registered insect repellant.
  • All EPA-registered insect repellants are evaluated for safety and effectiveness, and will contain DEET, picaridin, IR3535, Oil of Lemon Eucalyptus or para-menthane-diol as the active ingredient. Repellents containing a higher percentage of the active ingredient typically provide longer-lasting protection. Always follow the product label instructions.
  • Be careful using repellent on the hands of children as it may irritate the eyes and mouth.
• Get rid of mosquito breeding sites by removing standing water around your home:
  • Turn over any type of container that can collect water. Once a week, empty out items that hold water such as tires, buckets, planters, toys, pools, birdbaths, pet bowls, flowerpots, and trash containers.
  • Clean clogged roof gutters, particularly if leaves tend to plug up the drains.
• Treat standing water that cannot be eliminated, such as retention ponds or drainage ditches, with a mosquito larvicide. Mosquito larvicide is easy to use and can be purchased at most home improvement stores.
• Wear protective clothing such as long-sleeved shirts and pants.
• Limit outdoor activity from dusk to dawn when mosquitoes are most active.
• Maintain window and door screens to keep mosquitoes out of buildings. Do not prop open doors.
• Vaccines are available for horses that will protect them from EEEV. Contact your veterinarian for information regarding vaccinations.

Related Links

• CDC - EEE Page