Five horses in Maine have died in recent weeks of mosquito-borne Eastern Equine Encephalitis. State officials announced the two most recent deaths on Wednesday — one each in Unity and in the Cumberland County town of Gorham. Test results are pending for two more sick horses, one in Unity and one in the York County town of Berwick.
“These five dead horses with EEE indicate that there is a risk of people contracting the infection from mosquito bites,” said Dr. Dora Anne Mills, director of the Maine Center for Disease Control and Prevention.
Although the risk of human infection from a single mosquito bite is “very low,” she said Mainers should be especially vigilant in protecting themselves and their children from now until the weather turns cold enough to kill off mosquito populations.
“Until we experience several deep frosts, it is important people take precautions to avoid getting bitten by mosquitoes,” Mills said.
Recommendations include wearing long pants and long-sleeved shirts and applying repellents containing DEET for extended outings, especially near wetland areas. People also should cover infant carriers with mosquito netting and clean up standing water around their homes. Mosquitoes are most active at dawn and dusk.
All five horses confirmed to have the EEE virus had not been kept up to date on their vaccines against the organism, said State Veterinarian Dr. Donald Hoenig.
“It is important for horse owners to know there is a very effective annual vaccine for EEE and they should be sure their horses are current on this vaccine,” he said.
A horse in Stetson died with EEE last week, and two other horses, in Troy and Thorndike, died with the virus earlier in August.
Mosquitoes become EEE carriers by feeding on an infected bird — partridge, quail and songbirds are the most common hosts. Mosquitoes cannot pick up the virus by feeding on an infected horse or an infected human.
Once the virus is contracted, symptoms can develop rapidly over several hours. Symptoms in humans include fever, flu-like aches and pains, headaches and seizures. In horses, EEE is nearly 100 percent fatal. In humans, with hospitalization and supportive care, the disease is about 30 percent fatal. Half of all survivors suffer permanent neurological damage.
There is no human vaccine against EEE.
Maine CDC is testing mosquito pools in Waldo County and other areas of the state to help determine the geographic range of the virus. Although EEE has been detected in East Coast states for a number of years, the recent horse cases in Maine show the virus is present farther north than it has ever been reported before, Mills said.
Maine CDC will conduct a public meeting on Eastern Equine Encephalitis at 6 p.m. Thursday, Sept. 3, at the new Mount View High School in Thorndike.