West Nile virus (WNV) was confirmed June 18 in two dead blue jays found in northwest Houston, Texas. Veterinarians at the Texas Animal Health Commission (TAHC), the state’s livestock health regulatory agency, are urging owners of horses, mules, donkeys, and other equids to ensure that their animals have been vaccinated against not only WNV, but also against Eastern and Western Equine Encephalitis (EEE and WEE).

“The introduction of West Nile virus into Texas isn’t surprising, as we have monitored the south and eastward migration of the disease since it was first detected in North America in New York in l999. Last year, WNV was reported in 738 equids in 20 states,” commented Dr. Terry Conger, TAHC’s state veterinary pidemiologist. He explained that staff members from the TAHC and the Texas Department of Health (TDH), which focuses on human health issues, have worked jointly to share laboratory and surveillance information and educational materials about this disease which can be transmitted from infected mosquitoes to humans and equids, causing brain swelling and severe illness. Until l999, WNV was confined to Africa, Europe, Asia, and the Middle East.

Dr. Conger said that the cycle of disease for WNV requires two key players: birds, such as crows, blue jays or hawks, that act as a reservoir for the virus, and mosquitoes that become capable of transmitting disease after they take a blood meal from an infected bird. According to the Centers for Disease Control (CDC) in Atlanta, Georgia, there have been no documented cases of person-to-person, animal-to-person or animal-to-animal transmission of WNV. “We consider humans and equids to be ‘dead-end’ hosts, because they can become ill but haven’t been shown to spread infection.

“Late last summer, infected birds were detected in Louisiana and Arkansas,” said Dr. Conger.  “Now with the confirmation of infected birds in our state, the Texas Department of Health will probably find infected mosquitoes through their surveillance activities