Full Breakdown
Ancient Sheeppox DNA Unearthed in Medieval Manuscripts Links Millennia-Old Outbreaks to Modern Epidemics
By Drooid · · How we work
Core Event
Researchers from University College Dublin (UCD) announced that DNA from the sheeppox virus—a highly contagious disease of sheep and goats—has been recovered from the parchment of the York Gospels, a 1,000-year-old Latin gospel book produced in Canterbury in the late 900s and now housed at York Minster. The finding, published in *Science Advances*, shows that the virus left genetic traces on calfskin parchment despite the material’s lack of a natural sheep host. Similar viral signatures were identified in dozens of other medieval manuscripts across Britain, the Upper Rhine, Austria and France.
Background & Context
Sheeppox, a member of the capripoxvirus family related to smallpox, has long afflicted livestock in Eurasia. Prior ancient-DNA work recovered sheeppox genomes from Bronze-Age sheep teeth in Kazakhstan and Russia, dating to roughly 1,875–1,645 BCE and 1,336–1,130 BCE, establishing the virus’s emergence around 5,000 years ago. The new manuscript study extends that timeline, demonstrating that the pathogen persisted in European flocks for at least 3,700 years and that a distinct medieval European lineage existed before disappearing in modern times.
Data & Statistics
- The study screened 754 parchment samples spanning more than 14,000 years of Eurasian material and assembled 22 ancient sheeppox genomes.
- Roughly two-in-five (40 %) of the medieval books examined contained detectable sheeppox DNA.
- Seventeen positive detections came from medieval parchment; ten were from cattle parchment, four from goats, and three from sheep, with the York Gospels contributing three positive folios.
- Modern outbreaks in the Balkans between July 2025 and February 2026 involved 1,759 reported sheep and goat pox cases across five countries, with Greece alone reporting 1,549 cases and culling over 417,000 animals by December 2025.
Why It Matters
The preservation of viral DNA in parchment demonstrates that libraries and archives can serve as “biological time capsules,” offering genomic data that illuminate the long-term evolution of livestock pathogens. Because the sheeppox genome remained unusually stable over millennia, researchers argue that early genetic changes were pivotal to the virus’s adaptation to its hosts. Understanding these ancient steps may inform strategies to combat current sheeppox outbreaks, which continue to cause severe economic damage in Greece and neighboring countries.
Official Statements & Responses
- The European Food Safety Authority (EFSA) concluded in February 2026 that live-attenuated sheeppox vaccines provide 80-100 % protection and that adding vaccination to culling could clear the disease from Bulgaria a year sooner.
- Greek Prime Minister Mitsotakis rejected a mass-vaccination campaign in January 2026, arguing that insufficient biosecurity on the ground would limit its effectiveness.
Conflicting Reports & Gaps
- While the manuscript analysis places the emergence of a sheep-specific capripoxvirus at roughly 5,000 years ago, the UCD team highlights a minimum of 3,700 years of continuous presence in Eurasian flocks. The discrepancy reflects differing reference points (earliest known genome versus continuous detection).
- The exact mechanism by which sheeppox DNA entered calfskin parchment remains uncertain. Researchers propose two possibilities: contamination from sheep-derived glue used during parchment production, or a genuine infection of the animal hide prior to processing. One folio from the York Gospels showed abundant viral reads without accompanying sheep DNA, suggesting a true infection, but further sampling is needed to confirm this pathway.
What’s Next
The team plans to survey additional archives worldwide for hidden pathogen genomes and to locate cattle hides that exhibit both sheeppox DNA and visible pox lesions. Parallel efforts aim to compare medieval viral lineages with contemporary strains to clarify why the historic European lineage vanished and how modern control measures can be optimized.
