New research by academics points strongly to Viking settlers bringing leprosy to Ireland.
The findings came after five skeletal remains from graves in counties Dublin, Kildare and Antrim were examined by researchers who discovered a strain of leprosy which originated in Scandinavia.
The research project was carried out by academics from Queen’s University Belfast, the University of Surrey and the University of Southampton.
The results are being described as significant as little was known until now about leprosy in medieval Ireland.
Funded by the British Academy, the study focused on five cases of probable leprosy which were identified in human remains excavated from burials in Ireland.
Three of the individuals were buried in a cemetery in Dublin and the others in cemeteries in Kildare and Antrim.
Professor Eileen Murphy, from the School of Natural and Built Environment at Queen’s University Belfast, said 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.
Genetic investigations, also known as genotyping, were carried out on the leprosy bacterium (M leprae) strains in two of the Dublin individuals.
The strains, which were dated from the early 10th century to to the 13th century, revealed that the individuals had been affected by two types of leprosy.
One had probable origins in Scandinavia (type 3), while the other first developed in the Middle East (type 2).
“As past leprosy strains evolved, the genetic fingerprint of an archaeological case of leprosy can tell us about the possible movements of that individual.
"The two strain types discovered are highly similar to those present in cases in medieval Scandinavia, increasing the likelihood that this is the origin,” said Professor Mike Taylor, bio-archaeological scientist at the University of Surrey.
The Dublin skeletons were also chemically examined to determine where the individuals had spent their early years.
None of the three individuals appear to have been local to Dublin and, while one may have been from what it is now Britain or from the north of Ireland, tests showed the other two grew up in Scandinavia.