BILLINGS, Mont. (AP) - Montana livestock officials say a Park County cattle herd has been quarantined after six of the animals tested positive for the disease brucellosis.

State veterinarian Marty Zaluski said Tuesday additional testing on the herd is under way to confirm the disease, which can cause pregnant animals to miscarry.

The case mark's the region's 15th brucellosis infection in livestock since 2004, and Montana's fourth since 2007.

Brucellosis was largely eradicated from cattle nationwide last decade after a protracted government effort. It persists in wildlife in and around Yellowstone National Park.

Montana, Idaho and Wyoming have required more testing for the disease in recent years. That prompted the federal government to stop imposing trade restrictions automatically after infections.

The disease is not considered a significant threat to human health.

Copyright 2011 The Associated Press.