By Laura Zuckerman
(Reuters) - Investigators are probing whether anthrax played a role in the mysterious deaths of more than a dozen bison at an American Indian reservation in Montana, the state veterinarian said on Thursday.
Marty Zaluski said the bison, which have died since the start of the July 4 weekend at the Fort Belknap Indian Reservation, may have succumbed to anthrax. But he said more testing was needed to confirm what he emphasized was an early suspicion.
Anthrax bacteria can be found naturally in soils but the infectious and sometimes deadly disease it can cause is rare in humans and animals in the United States, according to the U.S. Centers for Disease Control.
Spores of naturally occurring anthrax can lie dormant in the environment for years without being ingested or breathed in by grazing livestock or wild animals, according to the CDC.
Zaluski said results from testing of tissue from one of the Fort Belknap bison will help agricultural, tribal and wildlife officials determine the gravity of the threat posed by the unknown illness.
"One thing we want to rule out would be anthrax," he said.
In 2001, a manmade variety of the disease was sent in letters through the U.S. mail in intentional attacks, sickening 22 people and killing five.
While the rapid deaths and other symptoms shown in the mostly female bison that died at Fort Belknap were suggestive of anthrax, it was premature to sound an alarm, said Zaluski.
The last anthrax outbreak in Montana occurred in 2008, killing 300 bison at a commercial ranch and also infecting several bull elk and a cattle operation's bull, he said.
The reservation's bison manager was out sick on Thursday and could not be reached for comment.
The Gros Ventre and Assiniboine tribes at Fort Belknap in 2013 were given 34 bison that originated at Yellowstone National Park and were confirmed free of brucellosis, a cattle disease.
Brucellosis is a leading reason that ranchers in Montana oppose furthering the conservation of the last U.S. herd of wild, purebred bison by establishing herds on Indian lands in the state.
The other conservation herd is managed by the Assiniboine and Sioux tribes of the Fort Peck Indian Reservation in northeastern Montana.
(Reporting by Laura Zuckerman in Salmon, Idaho; Editing by Curtis Skinner and Eric Walsh)