“Black Death” of the Middle ages blamed on bacteria

By Dr. Ananya Mandal, MDOct 10 2010

Black Death or plague that killed an estimated one-third of Europe's population in the Middle Ages has been ascribed to a bacteria called Yersinia pestis by anthropologists. The examined the teeth and bones from 76 skeletons found in “plague pits” in France, Germany, Italy and the Netherlands and DNA sequences showed that Y. pestis was responsible. There have been speculations earlier that the deaths may have been caused by an Ebola-style virus or the anthrax germ. This new finding dispels the previous notions.

The study was published in the open-access journal PLoS Pathogens. It also shows the geographical route taken by the germ, which is believed to have originated in central or southern Asia before arriving in Europe through trade.

Stephanie Haensch, a co-leader of the research, at Johannes Gutenberg University in Mainz, Germany said, “The history of this pandemic is much more complicated than we had previously thought.” The team tried to look for Y. pestis genes in the samples and match for either of two types of Y. pestis that are still present in parts of Africa, America, the Middle East and in the former Soviet Union. But neither of these modern types, known as Orientalis and Medievalis, showed up. Instead, two unknown types were found, both of them older than today's strains and different from each other. One of the investigators Barbara Bramanti said, “Our findings indicate that the plague traveled to Europe over at least two channels, which then went their separate ways.”