Michigan Reports First Human Case of Eastern Equine Encephalitis Since 2021
核心洞察
Michigan has confirmed its first human case of Eastern equine encephalitis (搜索) (EEE) in five years, diagnosed in a Roscommon County resident and potentially the first U.S. case this year.
EEE carries a 30% fatality rate among those who become ill, making it one of the most dangerous mosquito-borne diseases in the United States.
State and local health departments are intensifying mosquito trapping and testing in Roscommon County to monitor for further EEE activity.
Michigan has reported its first human case of Eastern equine encephalitis (搜索) (EEE) in five years, with the recent diagnosis of a resident of Roscommon County in Northern Lower Michigan. The Michigan Department of Health and Human Services (搜索) reported the case on Wednesday, and officials noted that this diagnosis may also represent the first human case of EEE in the United States this year.
"EEE is one of the most dangerous mosquito-borne diseases in the U.S., with a 30% fatality rate among people who become ill," said Dr. Natasha Bagdasarian, the state's chief medical executive.
Disease Burden and Recent History
Eastern equine encephalitis (搜索) is among the mosquito-borne viruses that can cause illness in both animals and, less frequently, in humans. An EEE outbreak in Michigan during 2019 resulted in 10 human cases, including six fatalities, along with 46 animal cases.
The Michigan Department of Health and Human Services (搜索) said it had not confirmed any animal-related cases so far this year, though cases were confirmed in domestic horses in Michigan during 2023, 2024 and 2025. As of mid-August, the Centers for Disease Control (搜索) had not recorded any human cases for 2026, with an average of 11 human cases reported to the agency each year. The CDC added that "due to delays in reporting, state, territorial, and local health departments may have more up-to-date information."
Surveillance and Response
Michigan officials said state and local health departments are working with the Michigan Department of Agriculture and Rural Development and the Michigan Department of Natural Resources to monitor for signs of EEE in humans, mosquitoes, domestic animals, and wildlife. The stepped-up efforts in Roscommon County include additional mosquito trapping and testing beyond the routine weekly mosquito population checks already scheduled for the season.
Mosquito population checks in Michigan so far this year have found signs of West Nile virus (搜索) and Jamestown Canyon virus (搜索). State officials said they have also found birds and a squirrel that tested positive for West Nile virus this year in Michigan.
Clinical Presentation
People who become infected with Eastern equine encephalitis (搜索) might notice fever, headache, chills and nausea, health officials said. The disease can worsen into inflammation of the brain.
Prevention Guidance
Health officials say the best way to prevent mosquito-borne diseases is to avoid mosquito bites. There are several insect repellents registered with the Environmental Protection Agency that people can apply to themselves before going outside when mosquitoes are active. People should wear shoes and socks, long pants, and long-sleeved shirts when they are outside in areas where mosquitoes are known to be present.
Because mosquitoes lay their eggs on or near water, people should also inspect their homes and outdoor spaces for potential breeding areas. Officials recommend cleaning and flushing the water in ornamental fountains, pet bowls and bird baths on a regular basis, and repairing or discarding containers that stay outside and might normally collect water.
"It is vital that Michigan residents take precautions against mosquito bites as mosquitoes can carry diseases that can have devastating health effects," Dr. Bagdasarian said.