Bubonic plague may have started in Kyrgyzstan, DNA analysis shows

The bubonic plague, a pandemic that may have killed around half of Europe’s population in the 14th century, likely originated from an epidemic in what is now Kyrgyzstan in central Asia.

The DNA of the pathogenic bacteria has been identified in the remains of people buried in the region from the year 1338, less than a decade before the bubonic plague reached European territory.

The genetic material of the microbe from Kyrgyzstan is practically identical to that found in plague victims in Europe, according to a study on the subject which has just been published in the scientific journal Nature. And inscriptions on Asian graves suggest it was already an epidemic – most deaths at this time in the place appear to have been caused by the infection.

The work was coordinated by Maria Spyrou and Johannes Krause, from the Max Planck Institute for Evolutionary Anthropology, Germany, and Philip Slavin, from the University of Stirling (UK).

clues

By combining the new genomic data with what was already known about the archaeological aspects and history of bubonic plague, the study has the potential to end the long-running debate about the origins of the disease, considered the most devastating pandemic in human history.

“We have known for a long time about the existence of these Christian cemeteries in Kyrgyzstan, in which epigraphic materials were found. [inscrições] wonderful,” Slavin told an online press conference.

In the 14th century, although the region was under the domination of the Mongol Empire, the local Christian community adopted the Syriac language (close to Aramaic, which was the mother tongue of Jesus and the apostles) in their texts.

The headstone in one of the graves, with the image of a cross, reads: “Year 1649 [equivalente a 1338 no nosso calendário]the year of the tiger [‘Bars’ na língua turca]. This is the tomb of the faithful Sanmaq. He died of ‘mawtana’ [pestilência, em siríaco]”Similar references appear in two contemporary cemeteries in the Lake Issyk-Kul region, near the mountains on the current border of Kazakhstan.

This index already indicated the Kyrgyz territory as a possible source of bubonic plague, the first reports of which in Europe date back to 1346, in the region of Crimea (now disputed by Russia and Ukraine). The genomes of the bacterium Yersinia pestis found in Christian graves by researchers exhibit exactly the characteristics expected of a close common ancestor of the bacterium that would begin to decimate Europeans a few years later.

Additionally, very similar strains of the microbe are still circulating in wild rodent (marmot) populations in Kyrgyzstan. Animals are considered the natural reservoir of the bacteria – nowadays humans are only infected when they come into contact with animals.

merchants

If the place may seem relatively remote and unknown today, it is important to remember that the situation at the end of the Middle Ages was very different.

“We are talking about a community of merchants who had long-distance connections to many different places, judging by the artifacts found by archaeologists in the area,” Slavin recalls.

The list includes objects from the Pacific and Mediterranean coasts, China (relatively close to the cemeteries) and the Middle East. And the very Christian group to which the dead belonged, the Nestorian Church, was spread across a wide area of ​​Eurasia, reaching as far as India. The unifying presence of the Mongol Empire also facilitated trade.

In other words, these connections may well have facilitated the spread of the initial outbreak westward. Exactly when the pandemic hit is a little more complicated to explain, however.

“In a way, it’s a perfect storm that brings together a lot of random factors,” says Johannes Krause. “An important element is that it had been several centuries since an epidemic of bubonic plague had affected Europe, which means that in the 14th century the bacterium began to infect a population which had no natural defense against her.”

lack of cleanliness

Another central factor is, of course, the why of Europeans and other peoples of the time. The main form of transmission of the disease was the bite of fleas carried by rats. In other words, filthy towns filled with people living with rats due to poor hygiene were jam-packed for the spread of disease.

“In fact, fleas only ended up sucking blood from humans when rats died by weight. In other words, people were just collateral damage from a rodent pandemic, in a sense “, explains Krause.

The main signs of the disease were the so-called buboes, a significant inflammation of the lymph nodes in the groin, neck and armpits. Those infected had a high fever, vomited blood and died within days.

Although sporadic cases still occur today, the immense improvement in hygienic conditions and the availability of antibiotics have put an end to outbreaks of bubonic plague, at least for now. (Reinaldo Jose Lopes / Folhapress)

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