In 1347, the Mongol Empire besieged the Black Sea port city of Kaffa, but could not capture it for a long time.
The mongol armies resorted to their usual poisonous tactic of throwing a corpse suffering from the "Black Death" into the city with a trebuchet and using virus warfare to destroy the defending army and people.
In the Mediterranean port of Sicily, the streets are bustling with people trying to make ends meet, and boats in the port are constantly coming and going. A convoy full of cargo sailed into the harbor from the Black Sea, and the people who had been waiting on the shore began to cheer when they saw the flag on the head ship. Because they knew that the cargo brought by this fleet meant great wealth, but what they did not know was that it also brought a nightmare that had enveloped Europe for centuries: the Black Death.
The plague, which originated in Central Asia, spread to Europe along with the Mediterranean trade, and the next four years of plague bacteria came like a god of death, mercilessly taking the lives of nearly 25 million people in Europe, regardless of men, women, young and old. Europe's population plummeted by a third, and in many places there were even ten rooms and nine empty spaces. This great catastrophe had a profound impact on European society, and even changed the class structure of the time and further formed a new social form. The Black Death made people suspicious of the church and laid the foundation for the later Renaissance.
Y. pestis belongs to the genus Yersinia and is the causative organism that causes the virulent infectious disease Plague. It is also a lethal bacterial warfare agent used by imperialism. Y. pestis is a short Gram-positive cocci, and the new isolates are stained with Melan or Jimsa, showing a thick stain at both ends with a capsular membrane (or envelope). Y. pestis is an aerobic and facultative anaerobic bacteria, and it is strongly resistant to the outside world, and it is not easy to die under cold and humid conditions.
There are two main ways of transmission of plague: the first is through the way of transmission through flea bites, commonly mouse-fleas-humans, that is, mice infected with Y. pestis did not die immediately, as carriers of the bacteria. Fleas bite the sick rat and then bite the person, or the fleas are bound to bite the rats that have been infected with the plague. Since Y. pestis only survives in the digestive tract after invading the body of fleas and does not survive in the anterior and middle stomach of fleas, the action of Y. pestis in fleas can cause the flea's digestive tract to block. This causes fleas to suck blood but can not be full, fleas transferred to people after sucking human blood plague bacillus will be with the blood spit out by fleas back into the human body, into the human circulatory system.
After the eleventh century, when the European Middle Ages entered their heyday, foreign invasions began to stop, and trade in inland rivers and coasts in Europe developed at an all-time high. The power of the church was greatly expanded, the population of the late Middle Ages began to grow, and more and more new cities began to emerge. The dependence of the countries on the Mediterranean coast on trade was greatly deepened, and many city-state states were fully committed to the maritime trade, and the emergence of capitalism began to emerge in society.
The widespread spread of Catholicism in Europe led to the rise of papal power at the time, and the story of Gregory VII's excommunication of Henry IV and forcing him to kneel in the snow for three days and three nights also appeared in this period. The Catholic gospel reached Scandina, and the ancient Belief in the Germanic gods began to decline. In addition, due to the lack of knowledge in that era, people under the influence of religious thought knew very little about medicine. When people get sick, they don't go to a doctor to treat themselves, but think that this is God's punishment for themselves.
In addition, due to the unequal status of men and women, women with the slightest talent will be executed as witches. The rise of the "witch hunt" has led to the destruction of cats that are treated as witches' pets, and many European countries and regions even regard the mass killing of cats as a carnival.
The massive influx of people into the city put enormous pressure on the sanitation of medieval cities. Because there was no unified urban planning as in the Roman period, most of the city's departments were narrow and cramped roads. The extremely rudimentary urban sorting system makes people dump their household garbage at will. Due to the inconvenience of life in the city, the frequency of bathing is greatly reduced. In addition to attracting large numbers of peasants to the cities, urbanization also attracted a large number of beggars, vagrants and abandoned children. Due to the lack of sufficient health knowledge in cities with excessive population density, cities have become the best place for mosquitoes, snakes and rats to multiply, and have also become a breeding ground for various bacteria. The late Middle Ages Xiaoice River, which caused a large number of rodents that could not forage in the wild, to flee to the city, laying a stealth bomb for the subsequent outbreak of plague.
All of the above makes the conditions for plague outbreaks in Europe excellent.
In the thirteenth century, new types of Y. pestis began to appear in Central Asia, but due to the sparse population in Central Asia, the bacteria could not be transmitted on a large scale. But the Mongol conquest of Europe caused many soldiers of the Mongol army to contract the plague before they reached Europe through the gateway to Central Asia. The heavy attrition of non-combat personnel caused by the epidemic of plague in the army slowed the pace of the Mongol Iron Horse's conquest. The Mongol army then touched the bodies of soldiers who had died of the plague through catapults into the city, and then the rats in the city spread. Naturally, rats boarded merchant ships bound for the Mediterranean coastal areas through cargo, and some of the crew members quickly appeared black spots, collapsed, delirious and feverish. He ended up dying in excruciating pain.
Due to the lack of understanding of the plague at that time, after the merchant ship docked, the crew and cargo landed smoothly. Soon after, the plague began to break out in the city, and many of the crew and people involved in the port work began to develop swollen lymph nodes and high fevers. Then the skin of the body began to appear large black spots, the hands and feet necrosis, and finally the organs of the whole body began to fail, and eventually went to death. The time from illness to death is as fast as a week, and it only takes one day. These people infected by rats and fleas are attacked first because glands such as lymph nodes are attacked, so the plague they suffer from is called bubonic plague. Some people infected with bubonic plague have plague bacillus invading the lungs of the human body, causing people to cough violently before they die, and the bacteria directly infect other people through the air with droplets, which is the 100% mortality rate of pneumonic plague. The plague virus competes for iron in blood cells in the body's blood, causing the body to appear dark spots and severed internal circulation, resulting in the inability of blood to be transported to nerve endings, resulting in necrosis of hands and feet. This plague is called septic plague, which in turn can infect normal people through blood contact and kill patients in a very short time. Because from the appearance, people suffering from plague will have symptoms of blackening of the body in the later stages, so people at that time called this terrible plague - the Black Death.
From Constantinople, the gateway to Europe, to the Mediterranean coast to France, Spain, and the Holy Roman Empire; from Greece to North Africa to Egypt, Syria, and Jerusalem in the Middle East; from England to Ireland to Northern Europe. Every time the Black Death passed through a town and village, thousands of people were taken to life by it. Although people began to realize the great power of this infectious disease, they began to close the city gates and block the roads, but they did not realize that rodents and fleas on their bodies were the way to spread the plague. Every day, several uninvited people still died of the plague, and even in many places later, they could not even get the manpower to dispose of the corpses. Church clergy have been on the front lines of contact with the epidemic because of their religious beliefs, but because their treatment methods are other than bloodletting, smoking, or waxing the bodies of patients, they can only pray to God to forgive those afflicted by diseases.
Desperate people began to line up to strip naked on the road while whipping their bodies in the street while loudly praying that God would forgive their sins. At the same time, the emergence of the disease began to be attributed to Jews, pagans, and lepers, and large-scale anti-Semitic massacres broke out across Europe, in which tens of thousands of Jews were executed as spreaders of the plague. Due to the disruption of business and the severe shortage of food supplies due to the quarantine of the epidemic, large-scale famine broke out across Europe. The death of a large number of clergy and a large number of people in the densely populated army who came into contact with the sick caused serious disruption to social order. Even Newton's Mathematical Principles of Natural Philosophy was written while he was fleeing the plague in the countryside.
From the thirteenth to the fifteenth century, the Black Death seemed to be a great nightmare hanging over Europe. The subsidence of the Black Death stemmed from the decline in population density, which led to a reduction in transmission routes, and on the other hand, from the rapid death of the host due to the strong lethality of the virus, which could not be effectively transmitted at all. Because it is too lethal, the number of people who die every day has far exceeded that of infected people, so the number of hosts continues to decline every day, and the efficiency and scope of transmission of infection naturally begin to decline. The invasion of the European brown house rat from India in 1727 gradually replaced the native European black house mouse, the fleas that parasitize the brown house mouse, unlike the Indian mouse flea (Xenopsylla cheopis) that parasitizes the black house mouse, when the brown house mouse died of plague or other causes, the horned leaf flea would hardly spread the infection in its mouthparts from the host to humans, because the horned leaf fleas are not interested in humans and only parasitize between rats. As a result, Y. pestis is confined to the brown rat colony.
In the centuries since, the plague has also seen massive outbreaks on every continent except Antarctica, with thousands of people each giving their names. Until the outbreak of plague in Hong Kong in 1894, the Hong Kong government at that time asked for help from all over the world. The French biologist Alexander-Yersin discovered the pathogen of Y. pestis and the relationship between the rat and the plague. Today's medical community, in honor of this great scholar, calls the pathogen of plague Yersinia pestis. With the mass production of antibiotics during World War II, the existing plague of plague is no longer an incurable disease, as long as it is treated in time, it can effectively study the lives of patients.
Plague bacillus as a kind of bacteria in nature, in the final analysis and probiotics in the human body is not much different in biological structure, rats and other rodents as an important link in the ecological circle, people can not all be extinct, so people can only learn to get along with a variety of bacteria in the right way in nature.