The plague epidemic known as the Black Death led to a significant reduction in the world's population seven centuries ago.. Despite the fact that the epidemic was so massive, the origin of its pathogen is still a mystery to scientists.. Now, researchers say they have discovered the original strain of the Black Death in 14th-century central Asia.. They studied ancient and modern DNA evidence for the existence of the disease and were able to trace the history of its occurrence, according to Discover magazine..

The Black Death raged across Europe, Africa and the Middle East around 1347-1352. Experts did not agree on how many people died as a result of the epidemic, it is estimated at 25-200 million victims, that is, from 5 to 40% of the world's population died.

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Once infected, the plague killed 70 to 80% of the carriers, the vast majority of whom died within five days.. And these five days they lived in agony. The temperature of the infected jumped, leading to chills, pain and delirium.. There were also painful swellings in the lymph nodes, called buboes, which ooze pus and burst in the later stages of the disease..

Even after the first wave passed in 1352, the plague continued to return for five centuries, periodically devastating the cities.. Despite the fact that the plague was so deadly, the causes of the Black Death remained unclear until the end of the 19th century.. In 1894, scientists discovered that plague was caused by a bacterium called Yersinia pestis.. This bacterium passed from rats to humans through blood-sucking fleas..

The fleas bit the infected rats and ingested the bacteria that clogged the flea's intestines and prevented them from eating.. Infected, starving fleas went berserk and jumped from rat to rat, leaving a trail of death and a population of infected insects in their wake.. Once the rat population dwindled, the fleas moved on to humans, and the deadliest pandemic in human history began..

Looking for the original source.

But when did the plague pass from rats to humans? This question has baffled researchers for centuries..

To accurately trace the origin of the plague, scientists turned to archaeological sites that date back to the 14th century from Central Asia.. Two burials were found in Kyrgyzstan, the tombstones of which testified that victims of the plague of 1338 were buried in them. Scientists have extracted DNA from the bones of the victim and found in them the DNA of the plague bacillus Y. pestis.

That is, the pathogen was already present in Central Asia before it reached Europe.. However, the researchers were never able to confirm that this was the original strain of the plague.. To do this, they turned to the study of "

When Y. pestis passed from rodents to humans, its genome quickly mutated and diversified - scientists called this event the Big Bang. Small changes in the A, C, G, and T nucleotides that make up the genome accumulated and eventually led to the Black Death.. By looking at different variants of the plague, researchers can determine what the ancestral strain looked like, which the researchers think they were able to find..

This strain is very similar to modern ones, which are found in marmots living near the archaeological site.. These animals likely harbored inactive versions of the bacterium between plague outbreaks.. The similarity between the genome of the bacterium found in the burial and in animals indicates that a person contracted the plague immediately after the bacterium passed from rodents to humans..

According to scientists, this indicates that the Black Death originated from Central Asia..