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State to spray high-risk areas to prevent mosquito-borne EEE infection

The Detroit News

Lansing — The state health department is urging local officials to consider canceling, postponing or rescheduling outdoor activities around dusk due to an uptick in cases of potentially fatal Eastern Equine Encephalitis. 

The state will also begin aerial mosquito control treatment in high-risk areas, it announced Monday.

As of Sept. 13, the mosquito-borne illness, known as EEE, has been confirmed in 22 horses in 10 counties in Michigan — Barry, Clare, Ionia, Isabella, Jackson, Kent, Mecosta, Montcalm, Newaygo and Oakland, according to the Michigan Department of Health and Human Services. 

Additional animal cases are under investigation, said the department. The cases are twice the animal cases as at the same time last year.

To date, no human cases have been identified. There is an EEE vaccine available for horses, but not for people.

Specialized aircraft will begin an ultra-low volume spray in early evenings until dawn. The same product used in 2019, Merus 3.0, will be used again. The health department says it contains 5% pyrethrins, a botanical insecticide extracted from chrysanthemum flowers. Pyrethrins are commonly used to control mosquitoes, fleas, flies, moths, ants and many other pests, and are approved for use in organic agriculture.

Monitoring in 2019 after more than 557,000 Michigan acres were treated found no increased human, animal or insect adverse effects, the state says.

Events where children are at risk include those in late evening, such as sports practices or games. The restrictions should continue until the first frost of the year, the department said. 

EEE is one of the most dangerous mosquito-borne diseases in the United States, with a 33% fatality rate in people who become ill. Those younger than 15 and over age 50 are at greatest risk of severe disease following infection.

Signs of EEE infection include the sudden onset of fever; chills; and body and joint aches, which can progress to a severe encephalitis, resulting in headache, disorientation, tremors, seizures and paralysis. Anyone who thinks they may be experiencing these symptoms should contact a medical provider. Permanent brain damage, coma and death may occur.

In 2019, there were 10 human cases of EEE in Michigan, which is equal to the total number of cases in the previous 10 years. Six people died.

Last year, Michigan accounted for 25% of the EEE cases nationally. It is unknown exactly why some years are more severe than others, although weather, including temperature and rainfall, are thought to play a role.

"As animal cases continue to grow, the risks to people increase as well," said Dr. Joneigh Khaldun, chief medical executive and chief deputy for health for the state, in a statement.

"People get EEE the same way horses do — from the bite of an infected mosquito — so a case in a horse means people in that area are also at risk. Limiting exposure at outdoor activities, especially near dusk when mosquitoes are most active, is the best way to keep you and your family safe from this deadly disease."

Tips to avoid mosquito bites

  • Avoid being outdoors from dusk to dawn when mosquitoes that carry the EEE virus are most active.

  • Apply insect repellents that contain the active ingredient DEET, or other U.S. Environmental Protection Agency-approved product to exposed skin or clothing, and always follow the manufacturer’s directions for use.

  • Wear long-sleeved shirts and long pants when outdoors. Apply insect repellent to clothing to help prevent bites.

  • 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 EEE, visit You can call the MDHHS hotline, which will now take calls for general questions about both COVID-19 and EEE, at (888) 535-6136. The hotline is open from 8 a.m. to 5 p.m., Monday through Friday.