The Black Death was a plague pandemic which devastated Europe from 1347 to 1352 CE, killing an estimated 25-30 million people. The disease, caused by a bacillus bacteria and carried by fleas on rodents, originated in central Asia and was taken from there to the Crimea by Mongol warriors and traders. The plague entered Europe via Italy, carried by rats on Genoese trading ships sailing from the Black Sea.

It was known as the Black Death because it could turn the skin and sores black while other symptoms included fever and joint pains. With up to two-thirds of sufferers dying from the disease, it is estimated that between 30% and 50% of the population of those places affected died from the Black Death. The death toll was so high that it had significant consequences on European medieval society as a whole, leading to the entire abandonment of many towns and villages. It would take 200 years for the population of Europe to recover to the level seen prior to the Black Death.

Cause & Symptoms
The plague is a disease caused by a bacillus bacteria which is carried and spread by parasitic fleas on rodents, notably the brown rat. There are three types of plague, and all three were likely present in the Black Death pandemic. Bubonic plague, the most common during the 14th-century CE outbreak, causes severe swelling in the groin and armpits (the lymph nodes) which take on a sickening black colour, hence the name the Black Death. The black sores which can cover the body in general, caused by internal haemorrhages, were known as buboes, from which bubonic plague takes its name. Other symptoms are raging fever, joint pains and the coughing up of blood.. If untreated, bubonic plague is fatal in between 30 and 75% of infections, often within 72 hours. The other two types of plague - pneumonic (or pulmonary) and septicaemic - are usually fatal in all cases

How Was Black Death Treated
Physicians relied on crude and unsophisticated techniques such as bloodletting and boil-lancing (practices that were dangerous as well as unsanitary) and superstitious practices such as burning aromatic herbs and bathing in rosewater or vinegar.

Meanwhile, in a panic, healthy people did all they could to avoid the sick. Doctors refused to see patients; priests refused to administer last rites; and shopkeepers closed their stores. Many people fled the cities for the countryside, but even there they could not escape the disease: It affected cows, sheep, goats, pigs and chickens as well as people.

In fact, so many sheep died that one of the consequences of the Black Death was a European wool shortage. And many people, desperate to save themselves, even abandoned their sick and dying loved ones. “Thus doing,” Boccaccio wrote, “each thought to secure immunity for himself.”

People Thought It To Be God’s Punishment
Because they did not understand the biology of the disease, many people believed that the Black Death was a kind of divine punishment—retribution for sins against God such as greed, blasphemy, heresy, fornication and worldliness.

By this logic, the only way to overcome the plague was to win God’s forgiveness. Some people believed that the way to do this was to purge their communities of heretics and other troublemakers—so, for example, many thousands of Jews were massacred in 1348 and 1349. (Thousands more fled to the sparsely populated regions of Eastern Europe, where they could be relatively safe from the rampaging mobs in the cities.)

How Did The Black Death End?
The plague never really ended and it returned with a vengeance years later. But officials in the Venetian-controlled port city of Ragusa were able to slow its spread by keeping arriving sailors in isolation until it was clear they were not carrying the disease—creating social distancing that relied on isolation to slow the spread of the disease.

The sailors were initially held on their ships for 30 days (a trentino), a period that was later increased to 40 days, or a quarantine—the origin of the term “quarantine” and a practice still used today.