Horse in York County put down after contracting mosquito-borne EEE

The disease transmission cycle of EEE. (Courtesy Cornell Wildlife Health Lab)

AUGUSTA, Maine - The Maine Center for Disease Control and Prevention is reporting today that a horse in York County was euthanized on Friday after it tested positive for the mosquito-borne viral disease Eastern Equine Encephalitis.

The horse had not been vaccinated against the disease, the agency said. It is the first detected case of EEE in a horse in Maine since 2013.

In a Sept. 7 issue of The Lebanon Voice, precursor to The Rochester Voice that same year, it was noted that mosquitoes bearing the illness had been found in a Lebanon test pool as well as in pools in Greenland, N.H.

According to the national Center for Disease Control, the Eastern Equine Encephalitis virus is transmitted to humans by the bite of an infected mosquito. It is rare in humans, and only a few cases are reported in the United States each year. Most cases occur in the Atlantic and Gulf Coast states.

Most persons infected with triple-E suffer no symptoms, but severe cases involving encephalitis, an inflammation of the brain, begin with the sudden onset of headache, high fever, chills, and vomiting. In these more severe cases, the disease is fatal about a third of the time.

The most acute form of the disease only presents symptoms in about four to five percent of infections, according to the CDC.

In September 2012 the death of 30 pheasants in Lebanon was attributed to triple-E.

The same year a Vermont man died from triple-E, and there were also several human infections in Massachusetts, but none proved fatal.

A vaccine for EEE and West Nile virus is available for horses, according to health officials, who note that horses who have not been vaccinated in the last six months should get an initial shot or a booster. The disease can also attack specialty livestock, like llamas, alpacas, emus, ostriches and other farm-raised birds, such as pheasants, quail and ducks.

Below are answers to commonly asked questions about triple-E from the Maine CDC.

1) What is Eastern Equine Encephalitis?

1. A) Eastern equine encephalitis is a rare but serious disease caused by the bite of an infected mosquito. Eastern equine encephalitis can infect humans, birds, mosquitoes, horses and some other mammals.

2) How is Eastern Equine Encephalitis virus spread to humans?

1. A) The virus that causes Eastern equine encephalitis is spread only by mosquitoes. People and horses with Eastern equine encephalitis do not spread the disease.

3) Who is at risk of getting Eastern Equine Encephalitis?

1. A) All residents who reside in areas where Eastern equine encephalitis virus has been identified in recent years are at risk of getting infected. People younger than 15 or older than 50 years of age have the highest risk of severe disease, if bitten by a mosquito that has the virus. However, please note NOT all mosquitoes can spread Eastern equine encephalitis.

4) What are some of the signs of Eastern Equine Encephalitis?

1. A) The first signs of Eastern equine encephalitis may include high fever (103°-106°F), stiff neck, headache, lack of energy, and inflammation of the brain. The disease gets worse quickly and some patients may go into a coma within a week.

5) How soon do signs of Eastern Equine Encephalitis virus infection appear?

1. A) Signs of eastern equine encephalitis show up 3-10 days after a person is infected.

6) How is Eastern Equine Encephalitis diagnosed?

1. A) Eastern equine encephalitis can only be diagnosed by a doctor. If you think you have any of the signs above, you should make an appointment to see your doctor as soon as you can. If your doctor suspects that you may have Eastern equine encephalitis, he or she will take your blood sample and draw a special fluid from your spinal cord (cerebral spinal fluid). Your doctor will then send these samples to the Maine Health and Environmental Testing Laboratory for specific tests to be done to see if you have the virus that causes Eastern equine encephalitis.

7) What is the treatment for Eastern Equine Encephalitis?

1. A) There is no cure for eastern equine encephalitis. However, supportive care is recommended to lower fever and ease pressure on the brain.

8) Is there a vaccine I can get for Eastern Equine Encephalitis?

1. A) Currently there is no human vaccine approved for Eastern equine encephalitis. However, vaccination for horses can be obtained by contacting a licensed veterinarian.

9) Is the risk of getting infected with Eastern Equine Encephalitis getting higher or lower each year?

1. A) The risk of getting infected with Eastern equine encephalitis in Maine is relatively low at the current time. However, prevention methods are still stressed because infection is always possible.

10) What time of year am I most likely to get infected with Eastern Equine Encephalitis?

1. A) People are at the highest risk of getting infected with eastern equine encephalitis between the months of May and October.

11) How can I protect myself and my family from getting infected with Eastern Equine Encephalitis?

1. A) You can protect yourself and your family from eastern equine encephalitis virus and other mosquito-borne viruses by taking the following actions:

Use insect repellent that contain DEET

Wear long-sleeved shirts, pants and socks when outdoors

Install or repair window screens

Avoid being outdoors at dawn or dusk

Drain standing water

More information about personal protection can be found by going to the federal CDC website at http://www.cdc.gov/EasternEquineEncephalitis/gen/qa.html#.

12) Do all mosquitoes spread Eastern Equine Encephalitis virus?

1. A) No, most mosquitoes do not spread the virus that causes eastern equine encephalitis.

13) Where do mosquitoes live and breed?

1. A) Mosquitoes lay their eggs in moist areas, such as standing water. The eggs become larvae that remain in the water until the adults mature and fly off. Weeds, tall grass, and shrubs provide an outdoor home for adult mosquitoes. They can also enter houses through unscreened windows or doors, or broken screens. Many mosquitoes will breed in containers that hold water, such as flowerpots or discarded tires.