State livestock officials are investigating a second confirmed case of brucellosis in Park County and a possible new case in Sublette County.

Wyoming Assistant State Veterinarian Bob Meyer said Wednesday the new case in Park County involves a herd of 1,400 bison. The state is working with the owner to test the entire herd. Three surrounding cattle herds also are being tested, even though the bison are fenced in, Meyer said.

It's suspected that elk may have been the source of the disease in the bison, he said.

"We want to make sure that any of the surrounding herds right around there didn't get the same exposures to the elk because the elk can jump over fences both ways," Meyer said.

The new case is not related to an earlier case discovered in late October in a separate cattle herd in Park County, located in northwest Wyoming. The state tested thousands of cattle in 12 herds in the first case and found no additiona l infections.

However, preliminary tests indicate possible brucellosis in one cow that was being put up for sale in Sublette County, which is in west-central Wyoming, Meyer said. More tests are being done to confirm the initial findings and more will be known sometime next week, he said.

The herd in question numbers about 650 head and there are four or five other cattle herds nearby, Meyer said.

The disease can cause spontaneous abortions, infertility and weight loss in cattle, elk, bison and other mammals. It persists in herds of wild elk and bison around Yellowstone National Park and has periodically passed to cattle in Montana, Idaho and Wyoming.

Until recently, if the disease was found in multiple cattle herds it meant costly restrictions on marketing of all Wyoming cattle to prevent brucellosis from spreading to other states.

However, the U.S. Department of Agriculture has eased its stance recently on imposing statewide restrictions and has assured the state that it will retain its status as being considered free of brucellosis, Meyer said.

"As long as we're doing a good investigation to make sure that we haven't got spread into any other herds - testing neighboring herds, testing in the area and doing a good investigation - they said your status will stay intact, meaning we won't have a downgrade in status from USDA," he said.

Copyright 2010 The Associated Press.