Bison tests positive for anthrax at Flying D, no repeat of 2008 outbreak expected
July 16, 2010
Samples from the carcass of a yearling bison heifer on the Flying D Ranch in Gallatin County (MT) has been killed by naturally occurring anthrax, according to animal health officials with the Montana Department of Livestock.
Field tests on the dead bison, found Monday near a pasture where the disease killed 287 bison two years ago, were confirmed Tuesday at the Montana Veterinary Diagnostic Laboratory in Bozeman. The pasture has been quarantined, said state veterinarian Dr. Martin Zaluski, and the ranch is monitoring its herd to quickly identify any additional cases that may occur.
Zaluski said a repeat of outbreak in 2008, which lasted three weeks, isn’t likely.
“Given the prophylactic measures implemented by the ranch after the outbreak in 2008, we would not expect to see many animals affected by the disease,” Zaluski said.
The positive test was not entirely unexpected, Zaluski said, as anthrax is known to be in the area. Most of the bison in the 2,500-head herd have been vaccinated against the disease at least once since 2008 and in most cases twice, although the dead bison had not been vaccinated due to its young age.
Livestock producers in the immediate area are encouraged to work with their local veterinarian to learn more about risks, prevention and treatment of the disease. Anthrax vaccines are effective and relatively inexpensive.
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“If your area has a history of anthrax, it’s not a bad idea to discuss prevention strategies with your veterinarian,” Zaluski said. “You need to be aware that the disease is there, just lying in the ground, and that there is no way to predict when it might surface.”
Anthrax is caused by a naturally occurring bacteria, Bacillus anthracis. Spores of the bacteria can lie dormant in the soil for decades, then become active under certain conditions, typically after climactic events such as heavy rains or flooding preceded by drought. Animals are exposed to the disease by grazing or consuming forage or water contaminated with spores.
Clinical signs of the disease include labored breathing, rising body temperature, staggering, depression, unconsciousness and convulsions. Untreated animals may die within 24-48 hours of exposure, and one or more animals are typically found dead without any recognition of early clinical signs.
A zoonotic disease, anthrax can be spread from animals to humans. Human infection usually takes the form of skin lesions and is generally the result of occupational exposure involving direct contact with infected animals or animal products such as wool, hides and horns. Montana has not had a reported case of human anthrax since 1961.
B. anthracis is fragile and easily inactivated by common disinfectants or exposure to moderate temperatures, and as such, poses virtually no risk to the food chain.
Additional information on anthrax can be found on the department’s Web site at: http://liv.mt.gov/liv/ah/diseases/anthrax/general.asp.