Two articles report the first direct genomic evidence that Yersinia pestis caused the Plague of Justinian and together revised views on how pandemics arise, recur, and spread, reported El Comercio. The research appeared in Pathogens and Genes.
Scientists identified Yersinia pestis in a mass grave at the ancient city of Jerash, Jordan, near the pandemic’s epicenter, reported The Economic Times. "Using targeted ancient DNA techniques, we successfully recovered and sequenced genetic material from eight human teeth excavated from burial chambers beneath the former Roman hippodrome in Jerash, a city just 200 miles from ancient Pelusium,” said Dr. Greg O’Corry-Crowe, co-author of the study. Historical texts indicated that the Plague of Justinian first appeared in Pelusium, in present-day Egypt, before spreading throughout the Eastern Roman Empire.
DNA analysis showed that plague victims in Jerash carried nearly identical strains of Yersinia pestis, a pattern consistent with a rapid and deadly outbreak, and confirmed the pathogen’s presence within the Byzantine Empire between 550 and 660 CE. “This discovery provides the long-sought definitive proof of Y pestis at the epicentre of the Plague of Justinian,” said Rays H. Y. Jiang, principal investigator of the studies. “For centuries, we have relied on written accounts describing a devastating disease, but lacked any hard biological evidence of plague’s presence. Our findings provide the missing piece of that puzzle,” Jiang said.
There was no previous direct genomic evidence of the Justinian Plague, and the cause remained debated; Yersinia pestis is the bacterium that causes plague, including the Black Death and other lethal outbreaks.
A complementary analysis in Pathogens found that Yersinia pestis circulated among humans for millennia before the Justinian outbreak and that later pandemics, including the Black Death and sporadic cases today, did not descend from a single ancestral strain but arose independently in different regions and eras, erupting in multiple waves from long-standing animal reservoirs. The pattern contrasted with the SARS-CoV-2 pandemic, which arose from a single spillover event and evolved primarily through transmission among humans.
The Justinian Plague, often described as the first recorded pandemic, lasted from 541 to 750 CE during the reign of Byzantine Emperor Justinian I and caused tens of millions of deaths, with some estimates up to 100 million.
"Jerash was one of the key cities of the Eastern Roman Empire, a documented trade hub with magnificent structures,” adding, “That a venue once built for entertainment and civic pride became a mass cemetery in a time of emergency shows how urban centres were very likely overwhelmed,” said Jiang. The hippodrome was repurposed as a mass grave between the mid-6th century and early 7th century, when written records described a sudden wave of mortality.
Experts concluded that pandemics were recurring biological events driven by population concentration, mobility, and environmental change, factors that remain relevant even today. While uncommon, Yersinia pestis continued to circulate worldwide; in July, a resident of northern Arizona died from pneumonic plague, the first such death in the United States since 2007, and last week another person in California tested positive for plague. "We've been wrestling with plague for a few thousand years, and people still die from it today," Jiang added, "Like Covid, it continues to evolve, and containment measures evidently can't get rid of it. We have to be careful, but the threat will never go away”.
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