Brucellosis is spreading, even as Wyoming tries to protect wildlife from the disease. This story follows the convoluted path of an exotic infection that cripples and causes abortions in cattle, harbors in wild elk and bison, and causes terrible night sweats and fever in humans. It entered the U.S. from the Mediterranean a century ago, flared up in domestic livestock, was the target of massive U.S.D.A. efforts, and now persists in wildlife in the Greater Yellowstone Ecosystem. This is the tale of one state wildlife biologist’s efforts to manage for the disease. Read the article.