Black Death

The plague of 1348-50, known as the Black Death or just "the Death," was the highly infectious disease now known as the bubonic plague; it's caused by a bacillus carried by fleas, which infest certain kinds of rodents including the prairie dogs of the American southwest. In its first pass through Europe it killed about one-third of the population and in some places as much as one-half; it returned to England, although in much less devastating fashion, two or three other times in the fourteenth century, and didn't finally disappear until after the so called Great Plague that devastated London in 1665. …