Brucellosis has been confirmed in a herd of Sublette County cattle in western Wyoming, and the herd has been put into quarantine.
The livestock producer's identity is protected by state law and kept confidential, but Wyoming state veterinarian Jim Logan was able to say that about 400 animals are in the herd and that he suspects the prevalence of brucellosis is low.
"At this stage of the game it's probably less than about 5 percent," he told the Jackson Hole News & Guide. "It's not a very heavily infected herd, which is good."
A strain of bacteria transmissible between cattle and elk, brucellosis causes animals to abort their first calf.
Logan said the Sublette County herd will remain in quarantine until positive cattle are identified and euthanized and the cattle free of brucellosis test negative three consecutive times. That testing will run into the early months of 2016.
The infected herd grazes on public and private lands, and Logan said he's "pretty sure" the disease was spread to the cattle from elk.
Since 2003, all of Wyoming's cases of brucellosis in livestock have stemmed from exposure to elk.
"It's sporadic," Logan said, "but we expect there will be an occasional outbreak because the wild elk in the Greater Yellowstone area are the last reservoir of the disease in the United States."
Brucellosis also was last found in Wyoming livestock this year in Park County.
Yellowstone National Park in recent years has slaughtered bison infected with brucellosis to keep them away from cattle in Montana in winter. Montana, unlike Wyoming, hasn't had brucellosis in cattle recently.