Tennessee Officials Urge Horse Owners to Protect Against EEE

The Tennessee Departments of Agriculture and Health this month urged horse owners to protect their horses from mosquitoes and to review vaccination records for Eastern equine encephalitis (EEE) and other mosquito-borne diseases including West Nile Virus (WNV). 

"Outbreaks of viral encephalitis in horses are a seasonal occurrence due to the prevalence of mosquitoes in late summer and early fall," said Ron Wilson, DVM, Dipl. ACVP, state veterinarian with the Tennessee Department of Agriculture. "Horse owners should be aware of symptoms of viral encephalitis and consult their local veterinarian if a horse develops any of the signs associated with this group of diseases."

Several states have reported cases of EEE in horses this season. Tennessee's first confirmed case of 2008 was reported the week of July 28 in Carroll County. The disease kills up to 90% of the horses infected with the virus.

Another mosquito-borne disease, West Nile virus (WNV), has also been seen in horses from all regions of the state during the past several years. Many of the signs of EEE are the same as those described for WNV in horses and include:

  •          Decreased alertness
  •          Blindness or impaired vision
  •          Aimless wandering or circling
  •          Head pressing
  •          Inability to swallow
  •          Weakness, paralysis, or convulsions

"Definitive diagnosis is important in tracking the spread of EEE and WNV infections,"said Wilson. "Horse owners should work with their local veterinarian to verify test results through laboratory analysis."

Vaccines are available to protect against EEE and WNV in horses. Horse owners are encouraged to review their records and consult a veterinarian regarding immunization for these diseases. Additionally, insect repellents can be used on horses, but often these repellents have limited effectiveness. Screened stalls can also help reduce exposure of animals to mosquitoes.

Humans cannot contract these viral infections directly from infected horses. However, mosquito-borne viral encephalitis does pose a public health risk, and people should take proper precautions to protect themselves.

"Because there is no EEE or WNV vaccine available for humans, people should avoid mosquito bites by using EPA registered insect repellents containing DEET, Picaridin, oil of lemon eucalyptus, or IR3535, and by wearing clothes that cover the arms and legs," said Dr. Rand Carpenter, a public health veterinarian with the Department of Health. "These preventative measures are especially important during the period from evening until morning, when mosquitoes are most active, or any other time mosquitoes become active."

Additionally, mosquito control measures are important for disease prevention. Mosquito control should include removal of all man-made potential sources of stagnant water such as discarded tires, containers left outdoors or clogged roof gutters that can provide a place for mosquitoes to breed.

The Tennessee Department of Agriculture's Kord Animal Diagnostic Laboratory in Nashville provides diagnostic services for livestock owners and private veterinarians. The department also offers diagnostic services now at the new West Tennessee Animal Disease Diagnostic Laboratory operated by the University of Tennessee at Martin in Martin, Tenn. For more information about EEE or other viral diseases in horses, contact the State Veterinarian's office or Kord Diagnostic Laboratory at 615/837-5120.

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