During the Middle Ages, great plagues swept across Europe, and the worst outbreak occurred in the 14th century, killing 25 million people. This deadly disease was called the Black Death, because those suffering from the disease would turn a blue-black color. Other names for it were bubonic, oriental, or Levantine plague. It spread from Asia and was brought by ships from the Black Sea to Mediterranean ports.
An 18th-century plague doctor wearing protective clothing. The beak contained “antiseptic” substances. The rod was to take pulses without touching the patient.
The pestilence was so infectious that villages were completely wiped out, and some reports say that one-third of all the people in England (the population was about 3 million then) died of it in two years. More than half the population of Asia and Europe may have died from the disease. In those days, when streets and houses were unhealthy and had no proper drainage, plagues happened fairly often, but the Black Death was the worst one ever known. Black rats became infected with the disease and the fleas from these animals hit other rats and humans, and so the plague quickly spread. A writer of the time said: “The cattle roamed master less over the countryside, crops rotted in the fields for lack of hands to reap them, and so few priests were alive that our Holy Father the Pope gave permission that laymen would minister to the dying.”
For the next 300 years the plague broke out at intervals, though never so badly again. With cleaner towns and rat control, the plague had practically disappeared from Europe by the end of the 17th century.
A plague epidemic began in China around 1894 and spread throughout Southeast Asia and India. During this epidemic, the plague bacteria were discovered by a Swiss scientist Aleixandre Yersin. He then developed an effective serum for inoculation against the disease.