U.S. federal officials are taking under consideration a tentative plan that requires capturing or killing infected elks in Yellowstone National Park, as they are believed to be the source of a serious livestock disease carried by animals in the area.

Government agencies have put down over 6,000 wild bison leaving the national park during the last 20 years in an attempt to control brucellosis, a highly contagious disease causing pregnant cattle to abort their young.

Cattle in areas of Wyoming and Montana where bison have not wandered for decades are being infected, and officials in both states are now pointing elk as the cause.

"We've got way too many elk," said John Scully, a rancher in Montana's Madison Valley. "Clearly with so many elk, the risk rises. We need to reduce their numbers."

The federal officials drafted a tentative proposal setting a goal of eradicating the disease — not just controlling it in bison and in elk.

According to livestock officials, contaminated elk herds around Yellowstone must be extracted.

Still, outfitters and hunters are trying to avoid the possibility of killing elk, being afraid that over-culling could diminish herds. They argue that wildlife managers should concentrate on vaccinating cattle or eradicating the malady in bison.

"I will fight that tooth and nail. As a sportsman, those wildlife are a public resource," said Bill O'Connell of the Gallatin Wildlife Association.

The greater Yellowstone National Park area in Idaho, Montana and Wyoming is populated by an estimated 95,000 elk, of which only a low percentage carry brucellosis, as experts estimate.

Cattle vaccines for brucellosis are only 60 to 70 percent effective, and it is contagious to humans, but cases are rare and commonly limited to those who work with infected cattle.