A dispute as bitter as a Montana winter rages between ranchers and environmentalists over Yellowstone National Park bison and a disease called brucellosis, which can harm cattle. In a National Research Council report, UC Berkeley and Iowa State University researchers have studied the problem and made recommendations.

The report, “Brucellosis in the Greater Yellowstone Area,” contains findings from Dale R. McCullough, UC Berkeley wildlife biologist, and Norman Cheville, veterinary pathologist at Iowa state.

Brucella abortus, the bacteria that causes brucellosis, can cause spontaneous abortion in cattle and other animals. It is transmitted primarily through reproductive fluids and nursing.

Last winter was extremely harsh in Yellowstone, and hundreds of bison died of starvation. Record numbers left the park, searching for forage at lower elevations. Alarmed that some of the itinerant animals might be infected with brucellosis, Montana livestock officials killed nearly 1,100 of them.

Ranchers worry not just that the disease will be detected in their beef herds, but that it will be detected in their states — which could lead to cattle trading restrictions. California has had brucellosis in the past, but recently regained its brucellosis-free status.

This winter has been mild in Yellowstone. No bison are known to have been shot. But McCullough and Cheville say their fate — and that of the area's elk (another carrier) and cattle — depends on steps taken to manage them all.

“To make the Yellowstone area brucellosis-free,” the authors write, “the disease must be eradicated in all three species simultaneously. A lot more research is needed to determine whether and how such an ambitious goal can be met.”

The draft report is on the Internet at www2.nas.edu/besthome/bisonelk.htm