Spraying for mosquito-borne virus begins in southwest Michigan

Evan James Carter
The Detroit News

Aerial spraying in parts of southwestern Michigan to fight the eastern equine encephalitis virus began Monday, state officials said.

The Michigan Department of Health and Human Services is spraying an insecticide in Berrien, Cass, St. Joseph and Van Buren counties to kill the mosquitoes that carry the virus, which has killed three people in Michigan.

Officials planned to perform the spraying Sunday, but postponed it due to the rain. They said updates on spraying could be found at Michigan.gov/EEE.

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 addition of three new animal cases and recent discovery of mosquitoes that carry this virus show this is an ongoing threat to the health and safety of Michiganders and the need for continued actions to prevent exposure, including aerial treatment,” said Dr. Joneigh Khaldun, MDHHS chief medical executive and chief deputy for health.

As of Monday, EEE has been confirmed in nine people, with three fatalities, the department said. In addition, cases have occurred in 33 animals from 15 counties: Allegan, Barry, Berrien, Calhoun, Cass, Genesee, Jackson, Kalamazoo, Kent, Lapeer, Livingston, Montcalm, Newaygo, St. Joseph and Van Buren.

The mosquitos that spread EEE are still active and were caught in traps set Sept. 26 in southwest Michigan, the department said.

Aerial treatment is conducted by low-flying aircraft, beginning in the evening and continuing up until 4:30 a.m. the next morning, in areas of concern.

The pesticides will be dispersed as an ultra-low volume spray. ULV sprayers dispense very fine aerosol droplets that stay suspended in the air and kill adult mosquitoes on contact.

EEE is one of the most dangerous mosquito-borne diseases in the United States, with a 33% fatality rate in people who become ill and a 90% fatality rate in horses, according to the health department. People can be infected with EEE from the bite of a mosquito carrying the virus. There is a vaccine for horses, but none for humans. 

Signs of EEE include the sudden onset of fever, chills, body and joint aches that can progress to a severe encephalitis, resulting in headache, disorientation, tremors, seizures and paralysis. Permanent brain damage, coma and death may also occur in some cases. 

The department does not expect the pesticides to have any health effects on humans or animals, Health and Human Services Department spokeswoman Lynn Sutfin said.


Twitter: @EvanJamesCarter