Hidden Plague? New Theory on How Disease Spread So Perilously

One reason the plague was able to spread so massively across Europe during the Middle Ages may have been that the bacteria that caused the disease lay hidden, in some unknown animal reservoir, for centuries, a new study reports. In the study, researchers in Germany hypothesize that the bacteria Yersinia pestis, which causes plague and killed millions of people, may have survived in Europe in an unknown host during the second plague pandemic, which lasted from the 14th to the 17th century. The id