The percentage of bison infected is low. The disease can only be transmitted if pregnant cows are exposed to the fetal birthing material of pregnant bison. Bison do not calve in the middle of the winter. Their exists an immunization shot for brucellosis to protect cattle growers who fear their herd might contract the disease. Brucellosis is not an endemic disease of bison.
Some people think the livestock industry therefore bears the onus for the infection.
In years past Montana has held a bison hunt just north of the Park to kill the bison officials fear could transmit the disease. This hunt has been controversial and in some winters hunters were beset by actions of animal rights activists. West of the Park, outside of the Park near Duck Creek, bison will also be corralled by a less efficient method. Those bison not successfully corraled are being shot instead. At Duck Creek all captured bison are tested for brucellosis.