Zaluski says a federal disease lab in Iowa determined the brucellosis strain that infected a heifer on a ranch in Pray was similar to strains found in elk and bison. The heifer had no contact with bison.

Brucellosis is a bacterial disease that causes cows to prematurely abort their young. The infection in Pray, Montana's second case in less than two years, will cause the state to lose its federal disease-free status. That will force livestock producers to pay for intensive testing on animals being shipped out of state.

Brucellosis has been eradicated elsewhere in the country but persists in the Yellowstone region's wildlife.