A disease caused by Yersinia pestis bacteria. It primarily affects rodents and is spread among them by fleas. A human bitten by an infected flea commonly develops swellings of the lymph nodes, called bubos, within seven to ten days. If the bacteria reach the lungs the victim develops pneumonic plague, which is infectious and deadly; victims may die within 24 hours. There have been many outbreaks of bubonic plague and three major epidemics: Plague of Justinian; Black Death; and a mid-nineteenth-century Asian pandemic. It is now treatable with antibiotics.