Franklin County Horses Test Positive for Eastern Equine Encephalitis


VAAFM Animal Health office (802)828-2421

The Vermont Agency of Agriculture, Food and Markets recommends that all susceptible animals be appropriately vaccinated for EEE by a veterinarian

MONTPELIER – The Vermont Agency of Agriculture, Food, and Markets received laboratory confirmation that a second deceased horse in Franklin County tested positive for Eastern Equine Encephalitis (EEE) virus. The two horses were located on separate properties. These two cases represent the first time there has been evidence of EEE in Franklin County. In 2012, two people and two horses from southern Addison County/northern Rutland County died from EEE.

EEE is a mosquito-borne, viral infection that can cause severe neurologic disease in horses, with mortality rates approaching 100%.  Although horses are the animals most susceptible to EEE, the virus can also cause disease in other mammals such as camelids (llamas and alpacas), and in emus.  In animals, the onset of clinical signs is generally three to ten days after a bite by an infected mosquito.  Mammals infected with EEE most commonly exhibit neurologic signs including ataxia or incoordination, inability to stand, limb weakness or paralysis, seizures and death, while infected emus often develop hemorrhagic diarrhea.  Mammals infected with EEE are dead-end hosts, meaning that they generally are unable to transmit EEE to other animals or to people.  Vermont cases of EEE are required to be reported to the Office of the State Veterinarian.  

 “Vermont owners of horses, camelids, and emus, regardless of where their animals are located in the state, should consult with their veterinarians to ensure that these susceptible animals are appropriately vaccinated for EEE”, reminded Dr. Kristin Haas, Vermont State Veterinarian.  Dr. Haas further stated, “Susceptibility of horses, camelids and emus to EEE infection is not linked to travel to shows, fairs or other commingling events.  Even animals that spend the majority of their time on isolated properties are susceptible and should be vaccinated”.    

Although vaccination is the most effective tool for preventing EEE in susceptible animals, owners may also protect them from infection by using an acceptable insect repellent seasonally and mechanical barriers such as fly sheets and face nets.  Changing out water troughs regularly and removing other items that hold water will help to reduce mosquito breeding areas.