Two cases of anthrax have been confirmed in deer from Uvalde and Val Verde counties in southwest Texas, and livestock health officials are urging producers in the area to consult their private veterinary practitioners about vaccinating livestock against this disease that resurfaces periodically.
Many long-time ranchers in the area have experienced sporadic outbreaks and routinely inoculate their livestock against this disease that is weather-dependent and can develop during warm spring and summer months.
“Anthrax is caused by Bacillus anthracis, a spore-forming bacteria,” says Dr. Dan Baca, a veterinary epidemiologist with the Texas Animal Health Commission (TAHC), the state's livestock health regulatory agency. “The disease often occurs after we have periods of wet, cool weather followed by a several weeks of hot and dry conditions.
“When livestock graze in an affected pasture, they can ingest the spores that are on the grass or ground. Historically, most of Texas' cases each year occur in a triangle bounded by Uvalde, Ozona and Eagle Pass.”
The area takes in portions of Crockett, Val Verde, Sutton, Edwards, Kinney, Uvalde and Maverick counties. However, if conditions are right, cases could occur anywhere in Texas, Dr. Baca said. In 1997, cases were confirmed in Edwards, Val Verde, Terrell, Webb, Starr and Uvalde counties. An anthrax case in 1997 also was confirmed in Parker County, in north Texas.
Dr. Baca said ranches with confirmed cases are quarantined until at least 10 days after all livestock are vaccinated and after proper disposal of all carcasses.
“By halting the movement of animals, any livestock exposed or incubating the disease will not spread infection to other ranches,” he said. “It's not unusual for one premise to have livestock losses, while livestock on an adjacent ranch remain healthy.
Anthrax is a reportable disease in Texas. While laboratory tests, conducted by the Texas Veterinary Medical Diagnostic Laboratory in College Station are needed to confirm infection, Dr. Baca said suspected cases also are to be reported to the TAHC at 1-800-550-8242.
A veterinarian is available to take calls 24 hours a day. If outbreaks occur in dairy animals, Dr. Baca advised producers to call the TAHC immediately for assistance to prevent potential human exposure through milk products.
Signs of the disease in livestock and deer can include sudden death, rapid bloating of the carcass, and blood oozing from body openings.
“After talking with several ranchers, we're assuming a number of suspected cases occur each year, but are not reported.” To prevent contaminating the ground with anthrax spores which can remain dormant for years, Dr. Baca said TAHC regulations require the property or livestock owner to thoroughly burn carcasses of animals that may have died from anthrax. The animal's bedding, manure and the surrounding soil also should be burned.
This keeps predators or wild pigs, coyotes or dogs from being exposed to the disease. Because anthrax strikes during dry periods, he said carcass disposal can pose its own dangers, so precautions must be taken to keep the fires from getting out of hand.
To avoid spreading spores, he said the TAHC recommends that carcasses be burned where they lay.
Pets should be kept away from dead carcasses. Bones of dead animals may also pose a disease threat. Healthy animals should be moved from anthrax-contaminated areas.
“It is possible for ranchers to contract a skin form of anthrax, so if any wounds appear to be infected, see your physician for appropriate antibiotic treatment,” he said.
“Although movies and popular mythology portray anthrax as an invariably fatal human disease threat, the often fatal pulmonary form of the disease is nearly non-existent in developed countries. Producers may want to talk with their physician or contact the Texas Department of Health if they have human health questions.”
“Hunters often ask about anthrax, and by the time hunting season starts, cool weather usually puts an end to any cases,” said Dr. Baca.
“However, my best advice always is to shoot only healthy-looking animals. By the time an animal displays signs of anthrax that can include staggering, trembling or convulsions, death is inevitable.”
Dr. Baca said several steps need to be taken when anthrax occurs:
Properly dispose of animal carcasses by burning to prevent exposure to other animals, such as predators or dogs. Remove healthy livestock from the area.
Vaccinate livestock if cases occur in the surrounding areas.
Because the anthrax vaccine is a “live” vaccine, it should not be administered concurrently with antibiotics. Vaccinated animals are to be withheld from slaughter for two months.
Restrict movement of livestock from an affected premise until animals can develop immunity through vaccination.