Eastern Equine Encephalitis (EEE)

Eastern Equine Encephalitis (EEE) is a rare disease that is caused by a virus spread by infected mosquitoes. 

Human cases of EEE disease are rare but can cause serious illness. Persons over age 50 and under age 15 seem to be at greatest risk for developing severe disease when infected with EEE. About 30% of people ill from EEE die and many who survive the infection are left with permanent neurologic damage. There are no vaccines to prevent EEE infection in people and no specific treatments for EEE disease.

The key to preventing EEE and other mosquito-related illnesses is to prevent mosquito bites and control mosquitoes in and around your home.

Learn more about symptoms, testing, and more on the Michigan Department of Health and Human Services' page or see FAQs from the Centers for Disease Control and Prevention.


In 2021, one person, nine horses, one deer, and five birds tested positive for Eastern Equine Encephalitis (EEE) in Michigan. No human or animal cases were reported in Washtenaw County in 2021.

See vector-borne disease data for Washtenaw County.