Cougars At Yellowstone Test Positive For The Bubonic Plague

While the rest of the world is battling a new infectious disease, cougars in Yellowstone National Park are fighting a much older disease: the plague.

In 2006, park officials noticed that cougars were dying under mysterious circumstances. Researchers tested 28 cougars in the park for Yersinia pestis, more commonly known as the bacteria for the bubonic plague that wiped out almost one-third of Europe’s population in the 14th century. Scientists found that half of the cougars tested had been exposed to the plague between 2005 and 2014.

Scientists also reported that they found Yersinia pestis present in roughly 47% of the cougars that were tested. They found the bacteria in four out of the 11 necropsies performed on the deceased cougars.

The disease could be more common in cougars than researchers think. One cougar tested negative twice for the bacteria over a three-year period, then tested positive the following year, and negative again the year after that.

Luckily, this infection does not pose a serious threat to humans.

This bacteria can be found in soil all over the globe. It maintains its existence in a cycle involving fleas, rodents, and other animals that are higher up the food chain. It can infect humans in a variety of ways, causing symptoms including fevers, weakness, and headaches.

Though the bacteria was responsible for roughly 100 million deaths during 1347-1353, it can now be treated by antibiotics. The World Health Organization reports that there are 1,000-2,000 cases of the bubonic plague annually in the world. The three countries with the highest rates of cases are the Democratic Republic of Congo, Madagascar, and Peru.

This research states that there is no reason to believe that cougars could spark an outbreak of the plague, as it is unlikely for infected cougars to pass the disease on to humans.

“The average person has essentially zero possibility of contracting plague from a mountain lion. So please, do not read into our results as a reason to fear mountain lions," said Mark Elbroch, lead study researcher.