Researchers from the University of South Florida (USF) and Florida Atlantic University (FAU), along with partners in India and Australia, have identified Yersinia pestis as the bacterium responsible for the Plague of Justinian. This pandemic, which began in AD 541, is recognized as the world’s first recorded pandemic and caused widespread devastation across the Byzantine Empire.
The discovery was made after genomic analysis of remains found in a mass grave at Jerash, Jordan. The site is located near where historical accounts first described the outbreak. Researchers sequenced genetic material from eight human teeth recovered from burial chambers beneath what was once a Roman hippodrome.
“For centuries, we’ve 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, offering the first direct genetic window into how this pandemic unfolded at the heart of the empire,” said Rays H. Y. Jiang, PhD, lead PI of the studies and associate professor with the USF College of Public Health.
Greg O’Corry-Crowe, PhD, co-author and research professor at FAU Harbor Branch Oceanographic Institute and a National Geographic Explorer, explained: “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.”
The research showed that victims carried nearly identical strains of Y. pestis between AD 550-660. This uniformity supports historical reports suggesting rapid spread and high mortality during outbreaks.
“The Jerash site offers a rare glimpse of how ancient societies responded to public health disaster,” said Jiang. “Jerash was one of the key cities of the Eastern Roman Empire, a documented trade hub with magnificent structures. That a venue once built for entertainment and civic pride became a mass cemetery in a time of emergency shows how urban centers were very likely overwhelmed.”
A related study led by USF and FAU analyzed hundreds of ancient and modern Y. pestis genomes to place these findings within an evolutionary context. The results indicate that plague pandemics—including later events like Europe’s Black Death—did not descend from one single ancestral strain but emerged independently multiple times due to longstanding animal reservoirs.
This pattern differs significantly from diseases such as COVID-19 (caused by SARS-CoV-2), which stemmed primarily from one spillover event followed by sustained human-to-human transmission.
“This research was both scientifically compelling and personally resonant. It offered an extraordinary opportunity to delve into the study of human history through the lens of ancient DNA at a time when we ourselves were living through a global pandemic,” said Greg O’Corry-Crowe, PhD. “Equally profound was the experience of working with ancient human remains — individuals who lived, suffered, and died centuries ago — and using modern science to help recover and share their stories. It’s a humbling reminder of our shared humanity across time and a moving testament to the power of science to give voice to those long silent.”
Recent cases highlight that plague continues to exist globally; for example, there have been deaths linked to pneumonic plague in Arizona as recently as July 2024 [https://www.cdc.gov/plague/index.html].
“We’ve been wrestling with plague for a few thousand years and people still die from it today,” said Jiang. “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.”
Building on these findings at Jerash, researchers are expanding their work by studying samples from Venice’s Lazaretto Vecchio—a major Black Death-era burial site—now housed at USF for further investigation into early public health responses.
The studies involved several researchers affiliated with USF’s College of Public Health; College of Arts & Sciences; Morsani College Of Medicine; FAU’s Harbor Branch Oceanographic Institute; as well as international collaborators in archaeology and genomics.
Funding came from sources including USF Provost’s CREATE Award; USF College Of Public Health Research Award; USF Microbiome Institute; alongside international partnerships.
