A single strain of bacteria has been confirmed as the cause of multiple pandemics, from the devastating 14th century Black Death to more modern plagues.
Yersinia pestis is known to have been the cause of the plague for some time, but researchers have now tracked how it spread across continents during recent centuries.
They have even dubbed it one of the "deadliest pathogens in human history."
"Our study is the first to provide genetic support for plague's travel from Europe into Asia after the Black Death, and it establishes a link between the Black Death in the mid-14th century and modern plague," said lead author Maria Spyrou of the Max Planck Institute for the Science of Human History.
This single strain caused both the Black Death and "recurrent outbreaks over the following four centuries". It then travelled to China, where it triggered a "third plague pandemic in the late 19th century".
The path of the bacterium was tracked using genome analysis. The team collected samples from the bodies of plague-infected people from mass grave sites in Spain, Germany and Russia.
"The mass burials where our samples come from often represent events where hundreds of people died of plague during a single outbreak," said senior author Alexander Herbig. "This gives us an impression about how significant the impact of this disease was during medieval times."
The Y. pestis DNA was found in 32 of the 178 individuals. Strains from Russia and Spain shared similarities with strains from London, for example.
"Our most significant finding revealed a link between the Black Death and modern plague," said Herbig. "Though several plague lineages exist in China today, only the lineage that caused the Black Death several centuries earlier left Southeast Asia in the late 19th century pandemic and rapidly achieved a near worldwide distribution."
The team now hopes to gain "additional insights" into its data to ascertain when and where the bacterium entered and exited Europe, as well as understanding how it evolved.
"We hope our findings will highlight the importance for more extensive sampling and sequencing of both ancient and modern plague isolates around the world, and open up new research themes regarding the role played by Europe and West Asia in plague's evolution and ecology," said the team.
Other recent research shed light on the way the Black Death affected communities a little closer to home, within the UK.
An in-depth analysis of pottery shards revealed the "eye-watering" impact the Black Death had across rural medieval England.
Towns, villages and hamlets were ravaged by the peak of the plague between 1346 and 1351, and between 75 and 200 million people are said to have been killed across Europe and Asia during several centuries of the disease.
This article was originally published by WIRED UK
