Why was the plague impossible to eradicate in Europe in the Middle Ages? Probably because the disease was really great at hiding in animals. German researchers recently discovered that the bacteria which causes plague was able to survive for hundreds of years.

Discovery News reports:

"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 idea came after the researchers analyzed the DNA from the skeletal remains of 30 plague victims who were buried at two grave sites in Germany. The researchers compared the data from the genetic analysis of these plague victims to the results of previous genetic analyses of skeletal remains of European plague victims from other countries."

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