Plague, Medieval Scourge, on the Rise (Michael Kahn)

  A bacterium known as Yersinia pestis causes bubonic plague, known in medieval times as the Black Death when it was spread by infected fleas, and the more dangerous pneumonic plague, spread from one person to another through coughing or sneezing.

  "Although the number of human cases of plague is relatively low, it would be a mistake to overlook its threat to humanity, because of the disease's inherent communicability, rapid spread, rapid clinical course, and high mortality if left untreated," they wrote in the journal Public Library of Science journal PloS Medicine. 

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