The Black Death, which caused the deaths of tens of millions of people in the fourteenth century, was caused bacterium Yersinia pestis. New evidence now shows that the same microscopic bacterium also caused the Plague of Justinian in the sixth century.
A team of scientists led by Dr. Barbara Bramanti of the Palaeogenetics Group at the Institute of Anthropology at Johannes Gutenberg University Mainz inspected an early medieval graveyard called Aschheim in Bavaria, Germany. Among the hundreds of remains they found some groups of people buried together that were dated to the sixth century. On the assumption that these bodies were of people who died in the Plague of Justinian and were buried in a mass grave, the scientists collected teeth from 19 skeletons to search for bacterial DNA.
Dr. Bramanti, whose work two years ago demonstrated beyond any doubt that Yersinia pestis also caused the pandemic known as the Black Death, said “For a long time scholars from different disciplines have intensively discussed about the actual etiological agents of the past pandemics. Only ancient DNA analyses carried out on skeletal remains of plague victims could finally conclude the debate.”
In results published last week in PloS Pathogens, the team confirms that Yersinia pestis was the cause of the Justinianic Plague of the 6th-8th centuries AD. This revolutionary result is supported by the analysis of the genotype of the ancient strain which provide information about the phylogeny and the place of origin of this plague. As for the second and third pandemic, the original sources of the plague bacillus were in Asia.
“It remains questionable whether at the time of the Byzantine Emperor Justinian only one strain or more were disseminated in Europe, as it was at the time of the Black Death,” suggested Bramanti and her Mainz colleague Stephanie Hänsch. To further investigate this and other open questions about the modalities and route of transmission of the medieval plagues, Bramanti has recently obtained an ERC Advanced Grant for the project “The medieval plagues: ecology, transmission modalities and routes of the infection” (MedPlag) and will move to the Center for Ecological and Evolutionary Synthesis (CEES) at the University of Oslo in Norway. The CEES, chaired by Nils Chr. Stenseth, has an outstanding and rewarded record of excellence in the research on infectious diseases and in particular on Yersinia pestis.