After being transmitted via the bite of an infected flea the Y. pestis bacteria become localized in an inflamed lymph node where they begin to replicate. Symptoms of plague is the infection of the lymph glands, which become swollen and painful and are known as buboes, as well as acral gangrene of the fingers, toes, lips and nose. Other symptoms include chills, malaise, high fever, muscle cramps, seizures, bleeding out of the cochlea.
Without treatment, the bubonic plague kills about two out of three infected humans within 4 days.
Black Plague appears in Fallout 2.