Year's first case of potentially fatal mosquito-borne illness confirmed in Michigan

Hani Barghouthi
The Detroit News

Michigan's first case of the Eastern Equine Encephalitis this year was confirmed in a Livingston County horse the Michigan Department of Agriculture and Rural Development in a statement Thursday.

EEE is a viral disease transmitted by mosquitoes to animals and people, and is considered highly dangerous. One in 3 people that become ill die of the disease, according to the release, as do 9 in 10 horses. 

It is typically seen in Michigan in late summer and early fall every year. Last year, four human and 41 animal cases were recorded. 

Horses can be vaccinated for the mosquito-borne disease, known as eastern equine encephalitis, but there is no equivalent for humans.

"The Livingston County horse was never vaccinated against EEE, and it developed signs of illness — including fever, lethargy, and depression — which progressed to the animal exhibiting neurologic signs and being down on the ground with an inability to get up," said state Veterinarian Nora Wineland, who made the diagnosis. "It is critically important for horse owners to reach out to their veterinarian to discuss how to best protect their animals from this disease."

People can be infected with EEE from the bite of a mosquito carrying the virus, but the disease is not spread by horse-to-horse or horse-to-human contact. In humans, symptoms include the sudden onset of fever, chills and body and joint aches.

The virus can also cause severe encephalitis, an inflammation of the brain, resulting in headaches, disorientation, tremors, seizures and paralysis. Permanent brain damage, coma and death may occur.

Dr. Joneigh Khaldun, MDHHS chief medical executive and chief deputy director for health, said the case indicates the virus is now in Michigan and warned that residents could also become infected. 

“Michigan residents are urged to take precautions and protect themselves from mosquito bites,” said Khaldun. 

Last fall, more than 462,000 acres were sprayed by planes to prevent the spread.

Mosquito-borne illnesses, like EEE, will continue to pose a risk to both animals and humans until late fall, when nighttime temperatures consistently fall below freezing, according to MDARD.

Residents can stay healthy by following steps to avoid mosquito bites:

  • Applying insect repellents containing the active ingredient DEET (or other U.S. Environmental Protection Agency-approved products) to exposed skin or clothing, and always following the manufacturer’s directions for use
  • Wearing long-sleeved shirts and long pants when outdoors. Applying insect repellent to clothing to further prevent bites
  • Maintaining window and door screening to help keep mosquitoes outside
  • Emptying water from mosquito breeding sites around the home, such as buckets, unused children’s pools, old tires, or similar sites where mosquitoes may lay eggs.
  • Using nets and/or fans over outdoor eating areas

For information about mosquito-borne diseases, visit  Michigan.gov/EmergingDiseases.