Montana livestock officials say a cow from a Madison County cattle herd has tested positive for the disease brucellosis.
The Department of Livestock said Friday that the animal was identified during testing by a rancher whose cattle graze inside a designated disease surveillance area around Yellowstone National Park.
Brucellosis can cause pregnant animals to abort their young.
State veterinarian Marty Zaluski says the ranch where the infection was found has been quarantined and adjacent livestock producers notified.
Brucellosis was first introduced by infected livestock brought in by European settlers. It's since been largely eradicated from cattle in the U.S., but persists in elk and other wildlife in and around Yellowstone.
The disease has been found in Montana cattle in five of the past eight years.