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West Nile Virus confirmed in two east Tennessee horses

October 6, 2006

Knoxville - The University of Tennessee College of Veterinary Medicine has confirmed West Nile Virus (WNV) in two horses in east Tennessee in the last week. The cases originated in Roane and Loudon counties. Five other positive cases have been identified throughout the state in 2006.

West Nile Virus is spread by infected mosquitoes and was first detected in the United States in 1999. The virus causes encephalitis, or inflammation of the brain. Mosquitoes acquire the virus from birds and pass it on to other birds, horses, and people. Last year, there were seven horse cases in Tennessee, down from previous year’s 17 cases.

Symptoms of WNV in horses include weakness in the hind limbs, stumbling, loss of appetite, fever, depression, lethargy, and muscle twitching. Contact a veterinarian if your horse shows any of these signs. WNV is fatal in up to 30% of the affected horses. Treatment includes supportive care and administering antibodies against the virus.

Dr. Frank Andrews, professor and clinician at the veterinary college says owners should keep horses’ vaccinations up-to-date. "We usually see a peak in the number of cases this time of year. Even if you haven’t vaccinated your horse, it’s never too late. There is a new vaccine available that doesn’t require a booster shot and would provide some protection against the virus," Dr. Andrews says. Dr. Andrews recommends that you contact your veterinarian for more information.

In addition to vaccination, preventing animals' exposure to mosquitoes is essential. Remove sources of standing water in which mosquitoes can breed. Mosquitoes can breed in any puddle that lasts more than 4 days. Avoid outdoor activity at dawn and dusk. If possible, maintain a circulating air-flow through horse barns and clean livestock–watering troughs on a monthly basis.

There have been no reports of human cases of WNV in East Tennessee this year. For more information visit the Centers for Disease Control and Prevention at or  the United States Department of Agriculture website, .

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Sandra Harbison
Media Relations
UT College of Veterinary Medicine

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