Another animal case of mosquito-borne EEE confirmed in Michigan

Horse diagnosed in St. Joseph

ST. JOSEPH, Mich. – Another animal case of Eastern Equine Encephalitis has been confirmed in Michigan.

A horse in St. Joseph first showed symptoms of the mosquito-borne illness Sept. 23, the Department of Health and Human Services said.

EEE has been confirmed in nine people in Michigan in Barry, Berrien, Calhoun, Cass, Kalamazoo and Van Buren counties. Four Michigan residents have died from EEE.

Animals from Allegan, Barry, Berrien, Calhoun, Cass, Genesee, Jackson, Kalamazoo, Kent, Lapeer, Livingston, Montcalm, Newaygo, St. Joseph and Van Buren counties have also had EEE.

More than 328,000 acres of land have been treated with insecticide to help combat the outbreak.

What is EEE?

  • Eastern equine encephalitis is a disease caused by a virus spread from infected mosquitos that can cause inflammation of the brain.
    • Viruses spread by mosquitos are referred to as arboviruses. West Nile is another kind of arbovirus.
  • EEE virus is transmitted through the bite of an infected mosquito. Transmission does not occur directly from person to person.
    • Only about 4-5% of human EEEV infections result in EEE.
  • It takes 4 to 10 days after the bite from an infected mosquito to develop symptoms of EEE.
  • Symptoms include: sudden onset of fever, chills, body and joint aches, severe encephalitis, headache, disorientation, tremors, seizures, and paralysis.
    • People who experience symptoms are urged to see a doctor as soon as possible. Those infected could get permanent brain damage, go into a coma, or die.
  • The virus is built up in a particular area through an amplification cycle:
    • Infected mosquitos feed on birds, infecting them in the process.
    • Uninfected mosquitos then feed on infected birds and become infected themselves.
  • EEE is typically found along the East Coast and Gulf Coast, along with the Great Lakes region.
  • Once an area has a hard frost, mosquito activity dies down and the virus goes dormant until spring.
  • A vaccine has been developed for horses, but no human vaccine is available.
  • In the US, an average of 7 human cases of EEE are reported annually.
  • The disease kills one-third of patients and leaves 80% of survivors with mild to severe brain damage.
  • Read more: Eastern Equine Encephalitis (CDC)

EEE in Michigan

  • As of Sunday, EEE was confirmed in nine people and three have died in six counties.
    • Barry, Berrien, Calhoun, Cass, Kalamazoo and Van Buren counties
  • Cases have also been confirmed in 30 animals from 15 counties.
    • Allegan, Barry, Berrien, Calhoun, Cass, Genesee, Jackson, Kalamazoo, Kent, Lapeer, Livingston, Montcalm, Newaygo, St. Joseph and Van Buren counties
  • Aerial treatments for several counties were scheduled for Sunday night, but were postponed due to weather.
    • Areas of Berrien, Cass, St. Joseph and Van Buren counties were set for treatment Monday night. A small part of northern Washtenaw County will also be treated.
  • Aerial spraying is used to control and reduce the number of mosquitos and reduce the chances for a virus to spread.
    • Airplanes spray very low volumes of adulticide or larvicide in areas where mosquitos are spreading viruses.
    • Larvicides kill larvae that hatch from eggs within 1-4 days.
    • Adulticides kill adult mosquitos immediately.
    • Read more: What You Need to Know About Aerial Spraying

How to protect yourself from EEE

  • Apply insect repellents.
  • Wear long-sleeved shirts.
  • Use window and door screens.
  • Eliminate mosquito breeding sites by emptying water from buckets, kiddie pools and tires.

Parts of nation see worst more than a half-century [article]

  • Three have died in Michigan, three in Massachusetts, two in Connecticut and one in Rhode Island.
  • Michigan’s EEE outbreak is its worst in more than a decade. Massachusetts, with 12 cases, is seeing its worst outbreak since 1956.
    • Aerial sprays have taken place a record six times this year in Massachusetts.
  • "It looks like 2019 is clearly the beginning of our next outbreak," said Catherine Brown of the Massachusetts Department of Public Health.
  • Brown believes EEEV is more widespread this year because of an ongoing extended period of warm weather.
    • Warm weather speeds up the reproduction process of mosquitos and the life cycle of the virus.
  • Brown says that outbreaks are often caused by a new strain being introduced to a region.
    • She believes a new strain of EEEV came to the Northeast from birds migrating from Florida.

About the Authors:

Brian is an Associate Producer for ClickOnDetroit. He graduated from the University of Michigan-Dearborn with a degree in Journalism and Screen Studies.