plague /plāg/ [L, plaga, blow] , an infectious disease transmitted by the bite of a flea from a rodent infected with the bacillus Yersinia pestis. Plague is primarily an infectious disease of rats: The rat fleas feed on humans only when their preferred rodent hosts, usually rats, have been killed by the plague in a rat epizootic. Therefore epidemics occur after rat epizootics. Aerosolized Y. pestis could be used to cause the pneumonic form in a bioterrorism attack. Kinds include bubonic plague, pneumonic plague, septicemic plague. See also Yersinia pestis.
