New research into the skeletal remains of five bodies has suggested the Vikings were responsible for bringing leprosy to Ireland.
Until now, little was known of how the infectious disease made its way to Ireland.
But a new study by researchers at Queen's University Belfast and academics in England, has indicated it could have come from Scandinavia with the Vikings during the ninth century.
Five bodies were excavated - three from Dublin, and one each from Kildare and Antrim - and the remains were tested for leprosy bacterium, from which a number of strains were identified.
Professor Eileen Murphy, from the School of Natural and Built Environment at Queen's University, said the study shone a light on the legacy of the Vikings in Ireland.
"Relatively little is known of leprosy in medieval Ireland. As an island located at the far west of Europe, it has the potential to provide interesting insights about the historical origin of the disease.
"Ireland is of particular interest in the history of leprosy as it was never part of the Roman world nor underwent any significant occupation by later Anglo-Saxon settlers.
"This study has revealed that despite its location on the western extremity of Europe, Ireland and, certainly, Dublin was not isolated."
Professor Mike Taylor, a bioarchaeological scientist at the University of Surrey, said the evidence suggested Scandinavia was the likely origin of the disease.
"The two strain types discovered are highly similar to those present in cases in medieval Scandinavia, increasing the likelihood that this is the origin," he said.