plague

plague An infectious disease that is caused by the bacterium Yersinia pestis, which mainly infects rats and other rodents. Fleas function as the prime vectors for carrying Y. pestis from one species to another. Transmission of the plague to people can also occur if people eat infected animals, such as squirrels. When someone has the plague, he or she can transmit it to another person via aerosol droplets. The plague has been responsible for devastating epidemics. The disease occurs at a consistent but low level in many countries, including the US. Yersinia pestis infection can be easily treated with antibiotics when detected early Also known as pest and pestis. See also bubonic plague; plague, bubonic; plague, black.