Bubonic Plague The disease is called the Bubonic Plague. It is caused by the bacteria Bacillus. Also now known as the "Bubonic plague". It is a plague because of its widespread fatality throughout history. The cause of this disease is the Yersinia petis bacterium. The Bubonic plague is transmitted from fleas to humans. You can contract the disease either by being bitten by the oriental flea, Xenopsylla Cheopis, or be exposed to plague infected tissue. The "Bubonic Plague" has an incubation period of 2 to 6 days. Within a week the body’s temperature rises to 104 degrees F. Shortly after they show signs of a fever other sym