CONCORD — The New Hampshire Department of Health and Human Services announced Wednesday that a horse from Northwood has been identified with the Eastern Equine Encephalitis 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.

State health officials on Tuesday also announced they had identified the first batch of mosquitoes in 2019 to test positive for West Nile Virus. The batch was collected in the city of Manchester on Aug. 21. DHHS is working with the City of Manchester Health Department to notify Manchester residents and those in the surrounding towns of the positive WNV test.

The Manchester Health Department continues its proactive surveillance program, which provides important and timely data that helps determine the risk level of mosquito-borne illness and the appropriate steps to protect the public’s health.

“This is the time of the season that we can expect West Nile Virus to be identified in New Hampshire,” said NH State Epidemiologist Dr. Benjamin Chan. “It is important for residents and visitors to take steps to prevent mosquito bites, as WNV and other arboviruses can be transmitted to humans from the bite of an infected mosquito. From this point in the season until there is a statewide mosquito-killing frost, the risk of infection by mosquito-borne viruses will increase. Use an effective mosquito repellent that contains 30 percent DEET, avoid being outdoors at dawn and dusk, and remove standing water from around the home, where mosquitos reproduce, to limit the risks of catching these infections.”

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

Chan said: “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 and West Nile Virus are two of three mosquito-transmitted diseases present in New Hampshire. The third is Jamestown Canyon virus (JCV).

EEE 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 and 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.

Prevention guidelines for EEE and other arboviruses can be found below. Anyone with questions about arboviruses, including EEE, can call the New Hampshire Bureau of Infectious Disease Control at (603) 271-4496. Fact Sheets on Easter Equine Encephalitis and other arboviruses are available on the DHHS website at For more information, go to the Centers for Disease Control and Prevention website at

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