West Nile Encephalitis

College Station, TX – Texans living near water are accustomed to annual warnings about St. Louis encephalitis. Now, they are warned of a new virus sure to make its way into the state. West Nile encephalitis, first detected in New York in the fall of 1999, has recently spread from the east coast to Louisiana and Arkansas, putting Texas veterinarians on alert for what may be the inevitable migration of the virus into the state.

“West Nile encephalitis belongs to the same group of diseases as St. Louis encephalitis, the Flaviviridae family, and is named for the area in Uganda, Africa where it was first detected in the 1920s,” said Dr. Ian Tizard, veterinarian and director of the Schubot Exotic Bird Health Center at the College of Veterinary Medicine, Texas A&M University. “This insect-borne virus spreads through the sting of infected mosquitoes and is carried by birds who act as reservoirs. While humans may become infected the condition isn’t usually too serious. Most healthy adults contracting the disease in the United States experience flu-like symptoms with no further complications. However, there have been a few fatal cases involving older patients. Among animals, the virus is most fatal to birds and horses.”

Because of the susceptibility of wildlife, veterinarians who notice an unusually high number of dead birds (particularly crows) are asked to file a report with the Zoonosis Control Division of the Texas Department of Health. In addition, surveillance programs are in place for the regular testing of dead birds, horses, captive waterfowl, and mosquitoes. The only commercial vaccine currently available for West Nile encephalitis is formulated for horses.

Since first detected, the virus has been largely seasonal in occurrence with most cases reported during warm weather months. The temperate Texas climate, however, is expected to sustain mosquitoes, and therefore West Nile, more continually than in northern climates. Naturally, Texas coastal areas, marshlands and other areas where mosquitoes breed in standing water and thrive are most likely to harbor infected mosquitoes.

“West Nile is essentially a bird virus,” said Tizard. “A disease like this could be devastating to Texas birds, especially the exotic bird industry and the whooping crane population. Although citizens should know that it is illegal to handle wild birds (dead or alive), many people elect to dispose of them using gloves and a plastic bag to keep pets from eating them. If there are several dead birds in one area, contact either the Texas Department of Health or the Texas Animal Health Commission, and they will send someone to investigate the cause of death.”

Established in 1916, the Texas A&M College of Veterinary Medicine is one of the world’s leading institutions in animal health care and research.

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