The bubonic plague was one of history’s most infamous pandemics.
Regarding the speed with which the plague killed, Italian writer Boccaccio said its victims often "ate lunch with their friends and dinner with their ancestors in paradise." The infectious agent of the bubonic plague, also known as the Black Death, was the bacterium Yersinia pestis. It struck Europe in the 1340s, spreading from Asia on infected rat-fleas aboard trade ships. The responsible organism entered through the skin and used the lymphatic system as its host. People were typically infected when bitten by a flea carrying the plague bacteria from an infected rodent. Bubonic plague was seen in the swellings, or buboes, that inflate the lymph nodes at the neck, armpit or groin. Some recorded symptoms include coughing, fever, and black spots appearing on the skin (hence the nomenclature).
The Black Death had three manifestations (bubonic plague, pneumonic plague, and septicaemic plague), which resulted in about 75 million deaths total, of which the bubonic plague claimed 25 million. Bubonic plague resulted in death for almost one out of every three people who contracted the disease.
Historians’ opinions are divided: some believe that Yersinia pestis could not have been to blame, this infectious agent has been found in the teeth of some plague victims. Even when the worst of the Black Death was over, smaller outbreaks continued into the 17th Century. Survivors lived in constant fear.
During the 20th century, this infectious bacteria was used by some countries to do research on and perpetrate biological warfare. In December 2003, Dr. Thomas C. Butler, a respected authority on infectious diseases and organisms at Texas Tech University, was convicted of illegally possessing samples of Yersinia pestis. He was accused and later convicted of lying about the plague bacteria whereabouts. To this day, the FBI has not recovered the samples in question.