Eastern Equine Encephalitis (EEE)



The Department of Health and Human Services will be conducting aerial spraying to kill mosquitoes that carry the EEE virus. Portions of Montcalm, Pierson and Eureka townships will be included in that effort. To see the spray schedule, visit:,4579,7-186-76711_77442---,00.html

 ****** Residents may opt-out of the spraying by sending an email with their name and full residential address to 

Before opting out, please remember that EEE is highly deadly, and that aerial spraying does not carry any significant risks to human or animal health.  Aerial applications provide the most effective option to suppress the outbreak by reducing mosquito populations. If an individual wishes to opt out of the application, under MDARD rules, an area of 1,000 x 1,000 feet would not be sprayed around the residence. This will reduce the overall treatment effectiveness in the area, mosquito populations upwind of the opt-out area will not be reduced, and neighbors will not benefit from the reduction in mosquito numbers.

While it is unnecessary to do so, you can further reduce your exposure to EEE during the application by staying indoors, and closing windows and doors.

The chemical that will be used is called Merus 3.O. It is an organic pesticide containing 5% pyrethrin. Pyrethrins are chemicals found naturally in some chrysanthemum flowers. The amount of chemical that will be used is so small that there is no risk to people, farm animals or pets. Residents inside the spray area will not notice anything—there will be no residue or odor of any kind.  Merus 3.0 is used regularly in other parts of the country to prevent EEE with no negative health effects.

Michigan is currently experiencing its largest-ever outbreak of Eastern Equine Encephalitis (EEE), with 8 human cases in 6 counties (Kalamazoo, Berrien, Barry, Cass, Calhoun and Van Buren). Three of those 8 human cases resulted in death. Eastern Equine Encephalitis has also been confirmed in 27 animals in 13 counties (Barry, Berrien, Calhoun, Cass, Genesee, Jackson, Kalamazoo, Kent, Lapeer, Montcalm, Newaygo, St. Joseph and Van Buren).

Eastern Equine Encephalitis is a disease found in birds, and spread between birds by mosquitos. Certain species of mosquitos can also spread the disease from birds to some mammals, like horses, deer, and humans. The disease cannot be passed between mammals, such as from horse to horse or horse to human.

People younger than age 15 and over age 50 are at greatest risk of severe disease following infection. Signs of EEE include the sudden onset of fever, chills, body and joint aches which can progress to severe encephalitis (inflammation of the brain).

Eastern Equine Encephalitis infection in humans is one of the most dangerous mosquito-borne diseases in the United States. Since 1980, there have been no more than 1 to 3 human cases identified in Michigan each year, primarily in southern and southwestern Michigan.

Avoiding mosquito bites is the best way to protect oneself from EEE and other diseases, like West Nile. Ways to avoid mosquito bites include:

  • Applying an insect repellent that contains DEET, or other Environmental Protection Agency-approved product to exposed skin, following the manufacturer’s directions.
  • Wearing long-sleeved shirts and long pants when outdoors.
  • Applying insect repellent to clothing. Permethrin is a particularly effective repellant for clothing.
  • Maintaining window and door screening to help keep mosquitoes outside.
  • Emptying water from mosquito breeding sites, such as buckets, unused kiddie pools and old tires.



EEE Frequently Asked Questions

Spraying for Mosquitoes in Michigan - Frequently Asked Questions

Montcalm Township Spray Map

Eureka Spray Map

Pierson Township Spray Map

Control Mosquitoes- Tip & Toss



  • For general health information regarding EEE, visit CDC
  • For updated information on EEE in Michigan, including case counts, visit MDHHS

For information about health effects from Merus 3.0, call the MI-Toxics and Health Hotline at 800-648-6942