Montana livestock officials said Tuesday that a Park County cattle herd has been quarantined after six of the animals tested positive for the disease brucellosis.

Additional testing on the animals was under way to confirm the disease, said state veterinarian Marty Zaluski. If confirmed, it would be the region’s 15th infection in livestock since 2004.

Introduced by early European settlers and once widespread, brucellosis has since been largely eradicated from cattle nationwide after a decades-long government effort. It persists in parts of Texas and in wildlife in and around Yellowstone National Park.