Deadly Mosquito-Borne Virus Confirmed In MI's First Human Case Since 2021

Michigan health officials on Wednesday confirmed an eastern equine encephalitis human case in Roscommon County.

It is Michigan's first human case of the serious and often fatal mosquito-borne illness in five years.

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Officials did not provide any further details about the case, but said additional mosquito trapping and testing efforts are underway in the area.

Michigan Chief Medical Executive Natasha Bagdasarian said eastern equine encephalitis is one of the most dangerous mosquito-borne diseases in the U.S.

"It is vital that Michigan residents take precautions against mosquito bites as mosquitoes can carry diseases that can have devastating health effects," Bagdasarian said. "EEE is one of the most dangerous mosquito-borne diseases in the U.S., with a 30 percent fatality rate among people who become ill."

EEE is a rare but serious disease that is spread to people by the bite of an infected mosquito. There are typically just a few human cases reported each year.

People who become ill with EEE may experience fever, headache, chills and nausea. In some cases, symptoms may progress to inflammation of the brain, signaled by disorientation, seizures and coma.

Physicians treating patients with these symptoms should consider testing for EEE and other mosquito-borne viruses and report suspect cases to their local health department. The MDHHS Bureau of Laboratories offers comprehensive testing for the arboviruses of concern in Michigan.

The virus is typically seen in late summer to early fall before it subsides when nighttime temperatures consistently fall below freezing.

The virus is also extremely deadly against horses, with a 90 percent fatality rate among horses in unvaccinated horses. There was at least one Michigan horse that died after contracting the virus last year.

The best way to prevent EEE, or any other mosquito-borne illness, is to reduce the number of mosquitoes around your home and to take steps to avoid mosquito bites, including:

• Use U.S. Environmental Protection Agency-registered insect repellents with one of the following active ingredients: DEET, picaridin, IR3535, oil of lemon eucalyptus or para-menthane-diol and 2-undecanone. Follow the product label instructions and reapply as directed.
• Do not use insect repellent on children under 2 months old. Instead, dress your child in clothing that covers arms and legs and cover crib, stroller and baby carrier with mosquito netting.
• Wear shoes and socks, light-colored long pants and long-sleeved shirts when outdoors.
• Make sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or other openings.
• Use bed nets when sleeping outdoors or in conditions with no window screens.
• Once a week eliminate all sources of standing water that can support mosquito breeding around your home, including water in bird baths, abandoned swimming pools, wading pools, old tires and any other object holding water.