BILLINGS, Mont. (AP) — U.S. Senators Jon Tester and Max Baucus are asking federal health officials to lift security restrictions on the bacteria that causes a disease found in wildlife in and around Yellowstone National Park.

The Montana Democrats said Tuesday that the restrictions are making research into a possible vaccine for the disease brucellosis more difficult and expensive.

Brucellosis can cause pregnant livestock and wildlife to miscarry. Human infections are uncommon and can be treated.

The government lists the bacteria as a possible biological warfare agent, which the senators say is "absurd" given that brucellosis is prevalent in the wild.

Tester and Baucus made their request to officials at the U.S. Department of Agriculture and the Centers for Disease Control and Prevention.