Equine West Nile not a Huge Problem for Kentucky to Date

West Nile virus is on the rise nationwide with more than 1,100 human cases reported as of Aug. 22, the highest at this point in the season since the virus was first detected in the United States in 1999. The U.S. Department of Agriculture's Animal and Plant Health Inspection Service National Animal Health Surveillance System reported fewer than 100 equine cases as of Aug. 18. In Kentucky the virus has been diagnosed in four horses since Aug. 2. One human case has been documented in Henry County and one in Clermont County, Ohio, just across the river from Campbell County.

"We are still in the high risk part of the season for West Nile infection," said Craig Carter, DVM, PhD, Dipl. ACVPM, director of the University of Kentucky Veterinary Diagnostic Lab (UKVDL). "The first case was diagnosed at the Breathitt Veterinary Center back on Aug. 2."

Carter said infected horses present with ataxia, which is a lack of voluntary coordination of muscle movements. Other clinical signs might include blindness, loss of motion in the hind limbs, circling, falling, and anorexia.

"As a horse owner or veterinarian, good surveillance is the key," he said. "Watch for a horse with neurological signs. Vaccination is not perfect, but it can often prevent and/or mitigate the illness. The good news is there is no evidence of person-to-person or animal-to-person infection. People are infected by the bite of a mosquito. Of course, you must always keep rabies in the back of your mind when dealing with animals that present neurological signs."

Many states have experienced both horse and human fatalities with West Nile virus this year. The Centers for Disease Control (CDC) and Prevention describe West Nile as a potentially serious illness, established as a seasonal epidemic in the United States that flares up in the summer and into the fall.

"Effective vaccines are widely available to aid in the prevention of WNV infection," said Robert Stout, DVM, Kentucky's state veterinarian. "I strongly advise horse owners to consult their veterinarians for implementation of a vaccination program. Virtually all cases seen in Kentucky have been in either nonvaccinated or undervaccinated horses."

Carter said the UKVDL and the Breathitt Veterinary Center can assist with diagnosis of West Nile virus in horses, and they can also perform necropsies on deceased animals. Contact either lab for more information on what samples are needed for diagnosis in potentially affected animals. Contact the VDL at 859/257-8283 or the Breathitt Veterinary Center in Hopkinsville at 270/886-3959.

The best way to avoid the virus in humans is to prevent mosquito bites. The CDC website states that approximately 80 percent of people who are infected with the West Nile virus never exhibit any clinical signs. More information about human infection is detailed on that website at www.cdc.gov/ncidod/dvbid/westnile/wnv_factsheet.htm. Human case numbers were taken from http://diseasemaps.usgs.gov/wnv_ky_human.html.

Aimee Nielson is an agriculture communications specialist at UK.

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