By Jonny Lupsha, News Writer

A couple in Western Mongolia have died of bubonic plague after eating raw marmot, The Guardian reported. There are people who believe eating the innards of the rodent is good for their health. Although people ignore health warnings not to eat uncooked meat, raw marmot can carry the plague germ Yersinia pestis. Plague is known for causing the Black Death in the 14th century—but was it that simple?

The small town of Bulyan-Ulgii in Mongolia faced a quarantine last week after a couple died of bubonic plague. According to The Guardian article, the couple contracted the deadly illness after eating the raw kidney of a marmot, which is a member of the squirrel family. Besides the locals, many tourists were stuck in the town for days and forbidden from leaving until Mongolian officials could confirm that there were no other cases of the plague in the immediate vicinity. The concern over the plague stems from its storied role in the Black Death, which decimated the world population beginning in the mid-14th century, but our perceptions of bubonic plague may need amending.

When History Doesn’t Add Up

Historically, we’ve always assumed that the Black Death was inextricably linked to bubonic plague—in fact, to some people, the two terms are used interchangeably. “The predominant theory is that a climactic event in China around 1346 caused the black rat population to have to leave its primary habitat and move into areas that brought the rats into contact with humans,” said Dr. Dorsey Armstrong, Associate Professor of English and Medieval Literature at Purdue University. “When the rat population had a sudden die-off, the fleas on the rats jumped to human hosts. Then, the humans and rats, and other animals, brought the plague with them along the trade routes that went from east to west in the medieval world.”

However, Dr. Armstrong pointed out that, contrary to what we’ve thought for quite some time, this can’t be the only thing responsible for the spread of the disease. Citing the research of late historian David Herlihy, Dr. Armstrong explained that there is virtually no mention in historical records of a massive dying off of the rat population during the time of the Black Death. She said that records persist of people seeking explanation for the Black Death in terms of volcanic eruptions, earthquakes, and planetary alignments, leaving a very slim chance that an event such as a rat pandemic would simply go unnoticed.

Another hole in the theory solely blaming the bubonic plague for the epidemic is that only pneumonic plague is transmitted from human to human, so otherwise, every single person who died of the Black Death—half of Europe’s population—would have to be flea-bitten or in close proximity with infected rats. Furthermore, the Black Death surged in the summer and quieted in the winter, but during the winter, people and rats would all naturally seek shelter in the warmth, so the death rates should be reversed.

Probable Causes

So, if bubonic plague wasn’t the only cause of the Black Death, what was? According to Dr. Armstrong, “Some reasonable theories about what else was part of the Great Mortality include tuberculosis, anthrax, [and] maybe a form of smallpox.” She also pointed to two other surprising studies. One study suggested that gerbils, not rats, carried the Black Death fleas. This would coincide with the weather cycles in Asia and explain the atypical times of mortality surges in the summer season in Europe.

The other study, originally published in 1979, blamed germs from outer space. “The term for this is panspermia, which is the idea that the seeds of life exist all through the universe, and those seeds move through the galaxies as parts of comets, asteroids, and other such bodies,” Dr. Armstrong said. When one of those bodies collides with Earth, the disease infects a host and spreads to other hosts. The scientists who put this theory forth argue that panspermia—or “vertical transmission” of a disease—explains why Yersinia pestis appears “in the 6th century, then again in the 14th, and then again in the 19th, with such long gaps between outbreaks,” Dr. Armstrong said. The scientific community has yet to fully adopt the vertical transmission theory, but it is certainly intriguing.

As unfortunate as it is that a couple in Mongolia has passed from bubonic plague, the world can at least be thankful that the incident was isolated. A better understanding of the disparities between plague and the Black Death will surely help allay the fears of the public.

Dr. Dorsey Armstrong contributed to this article. Dr. Armstrong is Associate Professor of English and Medieval Literature at Purdue University, where she has taught since 2002. The holder of an A.B. in English and Creative Writing from Stanford University and a Ph.D. in Medieval Literature from Duke University, she also taught at Centenary College of Louisiana and at California State University, Long Beach.