Preliminary tests indicate that Texas has its first equine West Nile virus (WNV) case. The sick horse was euthanized June 29 near Katy, Texas. West Nile virus was detected for the first time in Texas on June 18 near Houston; since then, 29 infected birds have been found.

“We were notified today (July 3) that tests run on samples of the horses’s blood and spinal fluid were positive for WNV. The tests were run both at the Texas Veterinary Medical Diagnostic Laboratory (TVMDL) in College Station, and at the National Veterinary Services Laboratory (NVSL) in Ames, Iowa,” said Dr. Linda Logan, Texas’ state veterinarian and executive director for the Texas Animal Health Commission (TAHC), the state’s livestock health regulatory agency.

“The NVSL is running additional confirmation tests on the blood samples, but more than likely, we are seeing Texas’ first case of WNV in a horse,” she said. “Diagnosing WNV must be based on laboratory confirmation, as the signs of the disease, including staggering or the inability to rise, can mimic other diseases, including rabies, or other encepalitic diseases, such as Western Equine Encephalitis (WEE) and Eastern Equine Encephalitis (EEE).”

West Nile virus was unheard of in North America until l999, when it was detected in birds in New York. The virus previously had been confined to Africa, Europe, Asia, and the Middle East. Birds harbor WNV, and it is spread by the bites of infected mosquitoes. See our West Nile Virus topic page for more articles