Recently, there have been reports of plague infection cases in China, Mongolia, etc., which reminds people of the horrible history of this severe infectious disease. In the Middle Ages, the plague brought about by the plague once and again killed 1/3 of the population in Europe The principle of disease was not discovered until the end of the 19th century. Who on earth saved Europe from the terror of the Black Death?
Since the 14th century, the plague has raged in Europe for more than 300 years. At the time, it was not clear how the plague spread. Whether it is traditional medicine, prayer or bloodletting therapy, it is completely ineffective in the face of the Black Death, and only brutal burning and isolation methods will have a little effect. Defoe, the author of “Robin Sun Rafting”, lamented in “The Plague Yearbook” published in 1722, “The plague (black death) defeated all the drugs”.
Humans really understand the pathogenic principle of plague, and it will be after the outbreak of large-scale plague in Hong Kong in 1894. Japanese bacteriologist Kita-Chai Saburo and French bacteriologist Yersin used the most advanced bacteriological theories at the time to find Yersinia pestis. Later, scientists discovered how the deadly bacteria spread through mice, and the practice of cutting off the spread of plague was improved by improving sanitary conditions and eliminating the environment in which mice grew.
However, the historical records can be clearly found, as early as the late 18th century, Europe stopped the outbreak of large-scale plague. Obviously, this kind of transformation did not come from the hands of human beings. It was not until modern scientists discovered the mystery through the investigation of rat population distribution. Earlier European mice were dominated by the black rat, a type of fleas carried on them-the Insect Flea is the main spreader of the plague. Insect flea carrying Yersinia pestis not only sucks the blood of the black rat, but also bites people or other animals at the first opportunity, thereby spreading the plague. However, in the early 18th century, the close relative of the black rat, the brown rat from Asia, started from southeastern Siberia and northern China, and gradually spread to various places along with human activities. In 1727, many historical materials documented the terrifying scene of millions of brown rat walking across the Volga and marching into western Europe. Allegedly, they may come from the migration of rats caused by an earthquake in India a few years ago. In the following years, such Asian mice appeared in many places in Europe. In 1769, the British zoologist John Beckenholt gave the Rattus norvegicus the scientific name “Norwegian Rat” because they migrated to the UK via a Norwegian ship in 1728, which shows that the Rattus norvegicus spread quickly.
Compared with the black rat, the brown rat is stronger and better at team fighting. They quickly replaced the black rat’s dominant position when they arrived in Europe. Rattus norvegicus is used to living in fields or gutters, and is far away from humans. Although Rattus norvegicus can also be infected with Y. pestis, they mainly carry another type of fleas, Ceratophyllum falciparum, and do not like to bite people. As the European Rattus norvegicus gradually replaced the Black Rattus, the channels for the spread of the plague were basically cut off, and large-scale outbreaks are no longer as easy to break out.
It is worth noting that the rattus norvegicus is only less likely to spread the plague than the black rat, but it is still an important source of infection for Y. pestis. Moreover, there are many kinds of rats, there are as many as 8 kinds of mice in Hong Kong where the plague broke out. In addition, the animals carrying Yersinia pestis are not only rats, but many rodents such as marmots and chinchillas can transmit this deadly disease. The large plague outbreak in northeastern China in 1910 was caused by a hunter preying on a sick marmot.
