The plague is a zoonotic disease, meaning that it is a disease that spreads among wildlife.ĭue to the close proximity between wild animals and humans, however, the plague has long infected people, too. NPS Photo/Diane Renkin Yellowstone National Park, where the infected cougars live.īut analysis of tissue samples from the cougar’s corpse revealed that the true culprit had been bacterium Yersinia pestis - the same bacterium that is widely believed to be responsible for the historic Black Plague of the 14th century that decimated the world’s human population.
