It was believed that black or ship rats (lat. Rattus rattus) contributed to the spread of the Black Death. But
In some parts of the world, the bacterium that causes plagueYersinia pestis has been found in wild rodents and their fleas for a long time. They are called animal “reservoirs.” Plague usually begins in rodents and sometimes spreads to humans. In Europe, there may once have been animal “reservoirs” that caused plague pandemics. But it also came to the continent from Asia. Scientists debate which of these scenarios is correct. The authors of the new study offered their own version.
According to an article published in Proceedingsof the National Academy of Sciences, environmental conditions in Europe should prevent the plague from surviving in permanent, long-term “reservoirs.” The authors of the study believe that the disease was reintroduced by Asian “reservoirs”, and European ones did not exist for so long.
Scientists have studied the characteristics of the soil,climatic conditions, types of terrain and species of rodents. All of this affects whether the plague can “survive” in different environments. For example, high concentrations of copper, iron, magnesium, abnormally high soil pH and low temperatures, high altitudes and less precipitation favor the development of stable reservoirs.
All the above conditions are in accordance with Chinaand the western United States at that time and are suitable for the survival of persistent Yersinia pestis in wild rodents. At the same time, the analysis showed that the likelihood of the existence of centuries-old “reservoirs” of plague in 1348 until the beginning of the 19th century was much lower than previously thought.
In Central Asia, long-term and sustainable“reservoirs” have existed for thousands of years. Research into ancient DNA and ancient documents has shown that once the plague entered Europe, it appears to have created only short- or medium-term “reservoirs.”
The study authors raise an important question aboutwhether the bubonic form of plague depended on sedentary rodents to transmit it, when instead it could have spread much more efficiently directly, from person to person. Scientists have suggested that this was due to ectoparasites (fleas and possibly lice) or through human respiratory systems and touch.
Earlier, a group of researchers from Germany and the UK discovered the DNA of the plague bacterium Yersinia pestis, which caused the Black Death, in graves in Central Asia.
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