The citizens of Toumai bury their dead during the black death. Photo: Wikimedia Commons

The genetic trail of the infamous Black Death has been linked to other outbreaks spanning the globe over centuries.

The Yersinia pestis contagion that killed an estimated 50 percent of the population of Europe in just six years (1347 to 1353 A.D.) was a bacterium that arrived in Europe from Asia – and then boomeranged back toward China for catastrophic outbreaks in the 19th century, according to the massive new DNA analysis in the journal Cell Host and Microbe.

It’s also likely that the same strain of the deadly germ was what caused the pandemic known as the Plague of Justinian, from the 6th to 8th centuries A.D. in the Byzantine Empire, they added.

“Our results suggest (1) limited Y. pestis diversity during the early phase of the Black Death, and likely a single entry into Europe; (2) a wave of plague that traveled eastward after the Black Death and late gave rise to the 19th century pandemic; and (3) an involvement of the same plague lineage in two post-Black Death European epidemics that are 200 years apart.”

The scientists extracted DNA from the teeth of 178 suspected plague victims spanning the globe. They evaluated the presence of Y. pestis using a species-specific quantitative PCR assay targeting a gene that activates plasminogen in the germ. Thirty-two individuals showed hits – and three had sufficient amounts of the DNA for a full analysis.

The DNA from the plague in Barcelona and London during the first catastrophic wave of the Black Death in Europe, along with subsequent flare-ups in Germany in the 17th century and Marseilles in 1720, showed the same plague germ was responsible for the death toll in the tens of millions.

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“Our phylogeny is compatible with popular demographic scenarios wherein the Black Death cycled through the Mediterranean (Barcelona), spread to Northern European (London), subsequently traveled east into Russia (Bolgar) and eventually made its way into China, its presumed origin and ultimate source of the modern plague pandemic,” conclude the authors, from the Max Planck Institute for the Science of Human History, and other institutions in Germany, Russian, France and Spain.