Medieval manuscripts made from animal skin reveal ancient history of deadly sheep virus

Published on 05/09/2026 - 8:36 GMT+2 In the Middle Ages, most texts were written on sheep, goat and cattle skin, used as a writing material and known as parchment. ADVERTISEMENT ADVERTISEMENT It is in some of Europe’s famous ancient manuscripts that researchers found clues into the history of the deadly sheep pox virus — a viral disease of sheep that causes fever, skin lesions, and death. Such traces can help scientists to understand how pathogens evolved and how they impacted past societies. An international team of geneticists, historians, virologists, protein chemists and conservators, led by scientists at University College Dublin, has extracted DNA from the skin used to make these centuries-old documents. “The recording of ancient DNA of pathogens has completely changed our understanding of infectious disease in the past, and here we show that parchment can also preserve animal pathogen DNA,” said Louis L’Hôte, lead author of the study. Among the works analysed were the 1,000-year-old York Gospels — one of the finest illuminated manuscripts to survive from the late Anglo-Saxon period — as well as earlier texts such as the Corpus Glossary at Corpus Christi College in Cambridge, regarded as one of the earliest English dictionaries. Other medieval texts examined came from across Britain and continental Europe. “It is possible that archives and libraries around the world also contain the genetic traces of disease outbreaks in animals in the past”. Sheep pox is a highly contagious disease that spreads rapidly and can affect large portions of a flock in a short time. It can cause significant economic losses due to decreased milk production, poor quality of hides and wool and trade restrictions. There is no evidence that sheep pox can infect humans. The study, published in Science Advances, found that in some cases, multiple pages from the same manuscript contained sheep pox virus DNA, suggesting that infected animals were used to produce them. The researchers combined the DNA found in the manuscripts with older samples from Bronze Age sheep teeth, and found that the disease has threatened livestock for over 3,700 years. “Ancient genomes can help us understand how these pathogens affecting us today evolved. We find that unlike the smallpox virus, the sheeppox virus genome was very stable over the last few millennia,” added L’Hôte. “This might mean that genetic changes before this point were very important to how the sheep pox virus evolved to infect its host, which may help us fight the pathogen in the future.”