The Virginia Department of Agriculture and Consumer Services (VDACS) has confirmed and announced Virginia’s first positive case of West Nile virus (WNV) in a horse for 2009. The 16-year-old Tennessee Walking Horse mare was from Pittsylvania County. Onset of clinical signs was Aug. 17 and necropsy at VDACS’ Regional Animal Health Laboratory in Lynchburg took place on Aug. 21. The Division of Consolidated Laboratory Services originally tested the brain for rabies, but when that was negative, they tested for other diseases and the brain was positive for WNV by polymerase chain reaction (PCR) testing. The mare had not been vaccinated for WNV.

Joe Garvin, DVM, head of VDACS’ Office of Laboratory Services, urges horse owners to check with their veterinarians about vaccinating their animals for WNV. “This is our first case of West Nile virus in a Virginia horse this year,” Garvin said, “plus we have had eight equine cases of Eastern equine encephalitis (EEE), as well as cases in a goat, emu, and alpaca. Both WNV and EEE are mosquito-borne diseases, and we generally start seeing our first cases in August and September. Since both diseases are preventable by vaccination; it makes sense for horse owners to go ahead and vaccinate now even though it’s late in the year. Mosquito season in Virginia can run through November