According to an Oct. 25 United States Department of Agriculture (USDA) Plant and Animal Health Inspection Service (APHIS) Emergency management warning, a horse in Greene County, Tennessee, has been confirmed as positive for West Nile virus (WNV) infection. These were the first confirmed equine cases of clinical WNV infection detected in Tennessee and Illinois.

The Tennessee horse was an eight-year-old mare that had to be euthanized on Oct. 6 after two days of illness. There was no history of travel or vaccination for WNV. The Illinois horse is a 5-year-old Thoroughbred gelding that became ill on Sept. 30, but has since recovered. There is no history of recent travel for this horse. WNV infection was confirmed at the National Veterinary Services Laboratories (NVSL) in Ames, Iowa, through positive results on a WNV IgM-capture enzyme-linked immunosorbent assay (ELISA) and a plaque-reduction neutralization test done on a serum sample.

WNV infection was confirmed in both cases at the National Veterinary Services Laboratories (NVSL) in Ames, Iowa, through positive results on a WNV IgM-capture enzyme-linked immunosorbent assay (ELISA) and a plaque-reduction neutralization test done on a serum sample.

More information on WNV, including WNV prevention and links to state and local WNV web pages, is available on the APHIS website at: https://www.aphis.usda.gov/oa/wnv/index.html. Also visit https://thehorse.com/wnv for updates on WNV