Black Death

The Black Death was a pandemic in Europe and Asia during the 14th century.
This outbreak of disease was at its worst between 1347 and 1351.
It killed between 50 million and 100 million people across Europe.
Historians cannot be sure which disease caused the Black Death. However, most think that it was the bubonic plague. That is a bacterial infection caused by the Yersinia pestis species of bacteria.
The Black Death may have begun in Central Asia or East Asia. It definitely appeared in Crimea in 1347. It was probably carried by fleas living on black rats, which traveled on Genoan ships and brought the plague to port cities around the Mediterranean. Rats may also have traveled along trade routes like the Silk Road and brought infected fleas to European cities. When the fleas bit humans, they infected them with the plague by injecting a bit of Y. pestis bacteria into the wound. Symptoms would start three to seven days later.
Not everybody agrees that plague caused the Black Death. Some historians have suggested that anthrax or a viral hemorrhagic fever caused the pandemic.
Impact
The disease killed around a third of Europe's population, but some areas were less affected than others. There were 75 to 200 million people across Eurasia died during the pandemic.
Until the 1700s, the plague seems to have reappeared in Europe at least once every generation. Some of the smaller plagues were more intense than others and caused more deaths. Later outbreaks include the Italian Plague of 1629-1631, the Great Plague of London (1665-1666), the Great Plague of Vienna (1679), the Great Plague of Marseille in 1720-1722, and the 1771 plague in Moscow. The most virulent form of the plague seems to have disappeared from Europe in the 18th century.
The Black Death had a very big effect on Europe's population. It changed Europe's social structure, which was a serious blow to the Roman Catholic Church and resulted in widespread persecution of minorities such as Jews, Muslims, foreigners, beggars, and lepers. The uncertainty of daily survival influenced people to live for the moment, as illustrated by Giovanni Boccaccio in The Decameron (1353).
At the time, 14th-century European writers called the pandemic the "Great Mortality". Later outbreaks made it become called the "Black Death".
Media
The Black Death appears in some modern literature and media, used as a subject or a setting. For example, Edgar Allan Poe's short story The Masque of the Red Death (1842) is set in an unnamed country during a fictional plague that shares many things in common with the Black Death.
Albert Camus's writings used that theme too. His novel The Plague (1947) ws set against an outbreak of the plague in Algeria and discussed how people handle the epidemic.
Medical aspects
In humans, the bubonic plague causes fevers, severe flu symptoms, and buboes. The last are large swellings filled with pus that usually appear in the groin, under the arms, on the thighs, and behind the ears. Buboes are black and purple, which may be how the Black Death got its name. The disease was painful, and many victims died horrible deaths.
The medical knowledge of the time was based on Hippocrates's theory of humorism, which said the body consists of different fluids. If they are in harmony, a person is healthy. If they are not, disease results. Very often, diseases were also seen as a punishment from God.
The theory of humorism did not explain why disease spreads from one person to another. Most people thought that infection was caused by miasma ("bad air"). The bad air could come from within the earth and so cause the disease. Remedies against the disease included opening only north-facing windows, not sleeping during the day, and not working too hard.
In 1348, Philip VI of France asked the Faculty of Medicine of the University of Paris about the cause of the Black Death. It concluded that the pandemic had been caused by a bad conjunction of Jupiter, Saturn and Mars on 20 March 1345. Since that answer was based on astrology, many people believed it, and it was translated into many languages.
Because nobody understood what caused the plague, doctors had no effective treatments. Often, doctors simply told their patients to go to Confession so that their sins would be forgiven if they died. Eventually, the pandemic caused doctors to change their ideas about how the human body worked. Just 200 years later, Girolamo Fracastoro discovered that diseases spread through infection.
Twelve plague outbreaks in Australia between 1900 and 1925 caused over 1,000 deaths, mainly in Sydney. That led to a Public Health Department, which did some leading-edge research. It found that plague transmission from rat fleas to humans by the bacillus Yersinia pestis.
Germ warfare
Mongol forces used the plague as a biological weapon in 1347. That was one of the earliest uses of germ warfare in history.
In Crimea, Mongol forces were fighting for control of Caffa, a Black Sea port (now Feodosiya, Ukraine). At the time, Caffa was a Genoese trade centre. Mongol forces began a siege. During the siege, they are reported to have catapulted plague-infested bodies over the walls into the city. Genoans fled the siege by using ships. Some historians believe the Caffa refugees brought the plague back to Italy with them, which started the pandemic.