The Black Plague (also known as the Black Death or Bubonic Plague.) was a disease, which killed as much as two thirds of the population during the Middle Ages.
Rat fleas spread the Black Plague. The flea gets the disease from the rat's blood, and then when it sucks a human's blood, the disease is spread into the human's blood stream.
When the Black Plague is in the body, a bacillus enters the blood stream. It goes to the lymph nodes causing them to swell, and to enlarge. When the lymph nodes swell, the temperature rises to between 38.3 degrees to 40.5 degrees Celsius (101 to 105 degrees Fahrenheit.) A purple color appears on the person's skin when they are close to death. .
The symptoms of the Black Plague are: headache, nausea, vomiting, weakness, and inability to walk. After two or three days of the symptoms, the swelling begins.
The Plague spread very quickly throughout Europe because most people were living in very poor conditions, and there was a lot of poverty and death going on. There was no running water, little food, and people rarely took baths. The food was rotten, and sometimes got thrown on the floor. This is why the Plague affected so many people, and spread so quickly.
The people affected by the Plague turned to their church (which was usually Roman Catholic) for help. The church nursed people, and took them into monasteries. Some of the people of the Roman Catholic church blamed their problems on the Jews.
Galen thought that the plague was spread by poisonous vapors, which came from swamps, and filled the air. He taught this to people. He warned people to avoid marshy areas and swamps, and to keep their bodies cool. Galen thought that people should wash their hands, and not their bodies, because when the pores were open, the disease could enter. Galen's theory was that the Black Plague was in the air.
Scientists have proved Galen's theory of the Plague wrong. The cures that he recommended did not help.