That’s right, plague. the same disease that has caused millions of deaths over the centuries has been found in cougars. A study in Yellowstone found that half the tested cougars had the disease. Wildlife biologists had thought that cougars were dying of starvation, but instead found that plague was the cause. Although humans are not generally at risk from contracting the plague because we are never near the animal, hunters should take precautions. The fleas that live on a cougar could jump from a carcass of a harvested animal and attach to a human host.
See and read more at: https://www.livescience.com/cougars-plague-yellowstone.html