Mosquito-borne disease worst outbreak in more than decade, Mich. officials say

Mark Hicks
The Detroit News

The Michigan Department of Health and Human Services is reporting a wider swath of the state where a deadly mosquito-borne disease has been verified, bringing the total number of cases so far this year to seven and making it the state's worst outbreak in more than 10 years.

The new reports of four more human cases, including two deaths, were announced Tuesday. That prompted state officials to urge communities in eight counties, mostly on Michigan's southwest side, where Eastern Equine Encephalitis, or EEE, has been confirmed in both animals and humans, to consider postponing or canceling outdoor activities until the first hard frost "out of an abundance of caution to protect the public health."

Eastern equine encephalitis is one of the most dangerous mosquito-borne diseases in the U.S. It can be fatal and often leaves survivors with brain damage.

The Kalamazoo County Health & Community Services Department also issued a similar recommendation to local municipalities and schools.

“Michigan is currently experiencing its worst Eastern Equine Encephalitis outbreak in more than a decade,” Dr. Joneigh Khaldun, the department's chief medical executive and chief deputy for health, said on Tuesday. “The ongoing cases reported in humans and animals and the severity of this disease illustrate the importance of taking precautions against mosquito bites.” 

There have been seven confirmed human cases across the state. Cases have been identified in Barry, Cass, Van Buren, Kalamazoo and Berrien counties, the department said in a statement. Besides the two recent fatal cases in Cass and Van Buren counties, a third death earlier was identified in Kalamazoo County.

There is a vaccine for horses but not humans, the state health department said.

The last year with such an increase in human EEE cases in Michigan was 2002, when there were six, said Bob Wheaton, a spokesman for the state health department, in an email Tuesday.

A larger number of cases involving animals has been verified: nine horses in Barry, Kalamazoo, Lapeer and St. Joseph counties, and five deer in Barry, Cass, Genesee, Kalamazoo, and Van Buren counties, the state reported Tuesday. 

Southwest Michigan has experienced outbreaks of the disease in people and horses in the past, with the most recent outbreaks in the early 1980s, mid-1990s and 2010.

Three people were infected in Michigan in 2016, state officials reported. According to the CDC, the state reported seven cases between 2009 and 2018.

Eastern equine encephalitis, or EEE, is among the most dangerous mosquito-borne diseases in the United States. It has a 33% fatality rate in people who become ill and a 90% fatality rate in horses, state health officials said.

EEE is carried by certain types of mosquitoes found primarily in areas with swamps and bogs, according to the state. 

The risk of bites from infected mosquitoes is highest for people who work or play outdoors in those areas. According to the Centers for Disease Control and Prevention, EEE is transmitted by mosquitoes that feed on infected bird hosts.

"Persons younger than age 15 and over age 50 are at greatest risk of severe disease following infection," the department said.

Signs of EEE include the sudden onset of fever, chills, and body and joint aches.

The condition can develop into severe encephalitis, resulting in headache, disorientation, tremors, seizures and paralysis. Permanent brain damage, coma and death may occur. 

To protect against disease-spreading mosquitoes, health officials advise residents to:

• Apply insect repellents with the active ingredient DEET, or other U.S. Environmental Protection Agency-approved product ,to exposed skin or clothing

• Wear long-sleeved shirts and long pants when outdoors

• 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

For information about mosquito-borne diseases, go to

The Associated Press contributed to this report.