Medieval plague strain sparked modern pandemics
European Black Death spread throughout the world in several waves
A single strain of plague bacteria sparked multiple historical and modern pandemics. This was revealed by the analysis of three reconstructed historical genomes from the causative agent of plague, Yersinia pestis, isolated from plague victims between the 14th and 16th century. The close relationship between strains causing different outbreaks in Europe led the international research team headed by the Max Planck Institute for the Science of Human History to suggest Europe as a medieval plague hotspot. The researchers study was just published in Cell Host & Microbe.
For four centuries following the medieval Black Death, plague was the most feared disease in Europe. Though now mysteriously absent in the continent today, plague persists in other areas of the world.
To investigate the evolutionary history of this notorious pathogen, three ancient genomes were reconstructed. These included one from Barcelona, Spain that most likely represents the initial swathe of the Black Death, one from a 14th century plague victim in Bolgar City, Russia subsequent to the Black Death, and one from a post-Black Death 16th century outbreak in Ellwangen, Germany. “By studying three plague victims from separate waves of the second pandemic, we were hoping to capture multiple stages of the bacterium’s evolution in medieval Europe”, says Maria Spyrou, lead author of the publication.
After 1350, historical accounts tell us that plague traveled northeast into Russia. What the history books don’t tell us is that plague didn’t stop there. The study published today provides evidence that 14-century Bolgar City was one stop along plague’s extensive and rapid travel that eventually brought it to Asia.
“Our analysis suggests that after the Black Death, European plague strains traveled eastwards, reaching the Golden Horde territory at the end of the 14th century and eventually making it all the way into China where they caused the third worldwide pandemic starting in the mid 19th century”, explains Johannes Krause, director at the Max Planck Institute for the Science of Human History.
Alexander Herbig, expert in Computational Pathogenomics and co-senior author of the study points out, “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.”
Plague hot-spot in Europe for several centuries
Although the Black Death subsided by 1353, plague outbreaks continued in Europe until the 18th century. The question of where this medieval plague reservoir was located has been controversial. Earlier this year, members of the team reported a putatively extinct plague lineage from the Great Plague of Marseille, 1720 – 1722, likely the last plague outbreak in Europe. Now, its close relationship with the 16th century Ellwangen genome suggests that plague did not stray very far. At a great distance to any coast, Ellwangen is far less connected to global trade routes than the bustling trade centre of Marseille. The presence of a shared plague lineage between the two cities led the research team to suggest Europe as a medieval plague hotspot.
“Evidence is accumulating to support the idea that plague was hiding somewhere locally within Europe for several centuries after the Black Death” says Kirsten Bos, molecular paleopathologist at the Max Planck Institute for the Science of Human History. "The reasons for its disappearance from Europe, however, remain a mystery."