DHHS Identifies First Horse With Eastern Equine Encephalitis

Concord, NH – The New Hampshire Department of Health and Human Services (DHHS) announced that a horse from Northwood has been identified with the Eastern Equine Encephalitis (EEE) virus infection. This is the first finding of EEE in a horse this year, though a mosquito batch from Pelham tested positive for EEE two weeks ago.

The arboviral risk level for the town of Northwood will be increased to high. The surrounding towns of Barnstead, Barrington, Deerfield, Epsom, Nottingham, Pittsfield, and Strafford will increase from low to moderate.

“We have had multiple positive tests for mosquito-transmitted viruses already this season in New Hampshire, and risk for human infection is likely to increase through the rest of the summer and fall,” said Dr. Benjamin Chan, NH State Epidemiologist. “Eastern Equine Encephalitis in particular, can cause serious brain infection and neurologic disease. With the holiday weekend approaching, we want people to enjoy outdoor activities, but it is critical for residents and visitors to take steps to prevent mosquito bites while outdoors, including using an effective repellent against mosquitoes, avoiding the outdoors from dusk to dawn when mosquitos are most active, and wearing long pants and sleeves to cover exposed skin.”

EEE is one of three mosquito-transmitted diseases present in New Hampshire, including West Nile Virus (WNV) and Jamestown Canyon virus (JCV), and was first identified in the State in August of 2004. Since 2004, there have been 15 human infections with EEE identified in NH; the last human case of EEE in NH was in 2014, when there were three cases. There have been no EEE infections identified yet this season in humans.

Any horse that resides in or travels to New Hampshire during mosquito season is at risk of becoming infected with EEE, WNV or JCV. Because of this risk, it is recommended that horse owners consult with their veterinarians to discuss appropriate vaccination schedules based on their risk factors.

Symptoms of EEE virus usually appear 4 to 10 days after being bitten by a mosquito carrying the EEE virus. People who get sick from EEE can develop a flu-like illness, including fever, headache, weakness, and muscle and joint pains. A more serious central nervous system infection can develop such as meningitis and encephalitis (inflammation of the brain). EEE typically causes a more serious disease than WNV and carries a high mortality rate for those who contract the serious encephalitic form of the illness. There is no specific treatment for the disease.