We finally know where the disease that killed more than a third of Europe comes from

We finally know where the disease that killed more than a third of Europe comes from

Despite its catastrophic toll, the exact geographic origin of the Black Death remained uncertain; researchers now claim to have determined it with precision.

The COVID-19 pandemic which has turned the planet upside down has at least had one advantage: it has served to remind the international community that these events constitute a major threat to our civilization, in particular when it demonstrates of convenience. In recent times, many researchers and laboratories have thus looked back on the great pandemics of History with the aim of drawing epidemiological lessons for humanity today.

And among the diseases that have wreaked havoc on our species, there is one that has a particularly terrible reputation: the plague. Today, this disease can be cured easily with modern antibiotics. But it is a very interesting example for researchers, as it is the origin of the very first pandemic to be widely described by many period observers.

A “Big Bang” of the plague that complicates studies

Thanks to these testimonies and numerous archaeological proofs, we know today that this disease really decimated Europe during an episode passed to posterity under the name of “black death”. Within five years, the bacteria Yersinia pestis ravaged the Old Continent; the exact toll remains highly debated, but the various estimates all point to several tens of millions of deaths.

Today, researchers estimate that the Black Death claimed the lives of more than a third of the European population, or even up to 60% depending on the sources. It is also established that was also a determining factor in the fall of powerful empires. Despite all these elements, doubts remain as to the origin of this evil.

This vagueness is due to an event that researchers describe as the “Big Bang” of the plague, which resulted in the appearance of many new strains of Yersinia pestis. Difficult, in this context, to trace the trail to determine its precise origin. But an international team of researchers now explains that they have found elements that point to the true starting point of this disaster.

Yersinia pestis, the bacillus responsible for the terrible black death. © Larry Stauffer – Oregon State Public Health Laboratory

The answer was hidden in multi-centennial teeth

According to New Scientist, the first evidence of the disease dates back to 1346, in present-day Crimea; historical documents claim that during a siege, assailants catapulted contaminated corpses into the city to force residents out; the fugitives would thus have transported the disease to Europe, thus accelerating the emergence of the pandemic.

But until today, no one knew which circuit the bacteria had taken to get there. To answer this question, researchers at the prestigious Max Planck Institute in Germany took the bull by the horns.

They were interested in two ancient cemeteries identified on a territory which today belongs to Kyrgyzstan, a state in Central Asia notably bordered by China and Kazakhstan. The 467 burials were documented in an old register which included a very evocative clue, namely the presence of the term “pestilience”; enough to put the chip in the ears of scientists.

They therefore identified the graves in question, which date back to the year 1338, and then carried out a genetic analysis of the teeth of the deceased. For the researchers, these elements are real little archaeological safes which remain preserved long after death, and which can keep traces of various pathogens – including Yersinia pestis. And that’s exactly what they found in two of their three workable samples.

The extent of the “Big Bang” of the plague is clearly visible on this tree of the strains of Yersinia pestis. © Spyrou et al.

The Black Death departed from Kyrgyzstan in 1338

This allowed them to carry out sequencing to establish a kind of family tree of Yersinia pestis. They were thus able to determine that the strain in question was a direct ancestor of the one that caused the black death a few years later. Moreover, the area in question is located precisely at the presumed location of the famous “Big Bang” which led to the appearance of new strains.

In other words, researchers are now almost certain that this is the precise origin of this devastating episode: everything now indicates that the Black Death left Kyrgyzstan in 1338. The original reservoir remains to be found ( researchers suspect local marmots), but it looks much more complicated.

© Spyrou et al.

But it is still very interesting information for researchers who document these phenomena. And it’s not just about filling out archives for the sake of it. As mentioned at the start of the articles, work of this kind allows us to refine our knowledge of the mechanisms that allow these dangerous pathogens to colonize large geographical areas.

These are details that might seem anecdotal, but which will all be important when anticipating and preventing a new pandemic which could be much more devastating than that caused by SARS-Cov-2…

The text of the study is available here.

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