The History of the Black Death

The epidemics progressively increased in spread, frequency and ferocity with a marked rise after 1550 because transport improved and the population of the towns steadily grew, thereby providing an ever-increasing pool of potential victims.

Combatting an Infectious Disease

The Italian Health Authorities were at the forefront of trying to control this infectious disease and, even in the fourteenth century and with no medical knowledge, had accurately established a quarantine period of 40 days. This became the gold standard for medical practice and proved to be completely reliable for the following 300 years. This epic discovery demonstrates that the pestilence (as the plagues were called) was directly infectious and was transmitted from one person to another.

Towns in France gradually realised that the danger lay in the arrival of an infected traveller who may well have come from a considerable distance. Entry was denied if they had come from a town that had suffered an outbreak. Once an epidemic had erupted, those displaying symptoms were removed to emergency primitive isolation hospitals that were hurriedly erected outside the town. Once a plague case had been identified, the family was locked up in the house, the well-known cross was daubed on the door and a watchman was appointed to stand guard.

In spite of only sketchy medical knowledge, the epidemiology of the plague was fully understood by the 17th century. Daniel Defoe had perspicaciously noted that, in the Great Plague of London in 1665, ‘because of its infectious nature, the disease may be spread by apparently healthy people who harbour the disease but have not yet exhibited the symptoms. Such a person was in fact a poisoner, a walking destroyer perhaps for a week or a fortnight before his death, who might have ruined those that he would have hazarded his life to save… breathing death upon them, even perhaps his tender kissing and embracings of his own children.’

Bubonic Plague

It is clear, therefore, that throughout the Age of Plagues, the disease was correctly recognised as a directly infectious disease and this belief continued until the end of the 19th Century. Why then is it popularly assumed that these devastating epidemics were outbreaks of bubonic plague, a disease that is spread to humans by rats and fleas? This bacterial disease had been grumbling in Asia for centuries, but in the 1890s it erupted violently and caused grievous loss of life. Steamships then carried infected rats and fleas from the infested warehouses of the Chinese ports to many of the warmer parts of the world, wherever suitable rodent hosts could be found, and the pandemic of the 20th Century had begun.