Maine Reports EEE Case

The Maine Center for Disease Control and Prevention in the Maine Department of Health and Human Services and the Maine Department of Agriculture's Animal Health and Industry Division announced last week that a 4-year-old Quarter Horse gelding euthanized in the town of Troy (Waldo County) tested positive for Eastern equine encephalitis (EEE).

Eastern equine encephalitis is a virus that is transmitted through the bite of an infected mosquito that has picked up the virus by feeding on an infected bird. The disease was first detected in Maine in 2005 among some horses, mosquitoes, and birds in York County.

"A horse with EEE does not pose a health threat to humans," said Dora Anne Mills, MD, MPH, director of the Maine CDC. "However, a horse with EEE indicates that local mosquitoes are infected, contracting it from birds. Since mosquito bites are how EEE is transmitted to humans and horses, it is important people and horse owners take precautions.

"We had regarded southwest Maine as the perceived area of greatest risk for EEE," said Don Hoenig, VMD, state veterinarian with the Department of Agriculture. "However, this case in Waldo County indicates that the area may be much wider."

In horses, EEE is a highly fatal disease with mortality approaching 100%. Infected horses can exhibit clinical signs of illness within three to 10 days of being bitten by an infected mosquito. Clinical signs include unsteadiness, erratic behavior, and a marked loss of coordination. There is no effective treatment and seizures resulting in death usually occur within 48-72 hours of an animal's first indications of illness.

"All horse owners should be sure their horses are current on their EEE vaccination, as this is a very effective vaccine," reminded Hoenig. "The horse that was positive in Troy was not vaccinated."

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