New research into the origins of leprosy in Ireland has revealed connections with the Viking world.

A team from Queen’s University Belfast, the University of Surrey, the University of Southampton, and the University of East Anglia analysed five skeletons: three from Dublin (SkCXLVIII, SkCXCV, SkCCXXX), one from Armoy, Co. Antrim (Sk171), and the last from Ardreigh, Co. Kildare (Sk1494). All five presented with lesions consistent with leprosy, but to confirm the diagnosis the team conducted aDNA analysis of the remains.

M. leprae, one of the bacteria that causes leprosy, was found in all three of the Dublin skeletons and was well-preserved enough to be genotyped in SkCXCV and SkCCXXX. Interestingly, despite both skeletons dating to roughly the same period – the 12th-13th centuries and 11th-13th centuries respectively – they each carried a different strain of the bacterium. SkCXCV was infected with the 3I-1 strain, while SkCCXXX was infected with the 2F lineage.

The feet of the individual from Armoy, Co. Antrim, showing lesions consistent with leprosy. (IMAGE: Professor Eileen Murphy, School of Natural Built Environment, Queen’s University Belfast)

The 3I-1 strain has been positively identified in remains from archaeological sites in Britain, Denmark, and Sweden. While the dataset is still small, the grouping and chronology of those infected suggests possible Scandinavian roots. It is also this strain that was recently identified in red squirrels from Brownsea Island, suggesting a possible link between the Viking fur trade and the spread of the disease (see CA 337). The 2F strain appears to have been prevalent in northern Europe as well, but a single case has also been identified in Italy and other research suggests that a precursor of this strain may have originated in the Middle East.

Solidifying the possible Viking link, isotope analysis of the Dublin remains revealed that none of the three individuals were local: while one may have had British or Irish origins, the other two probably came from Scandinavia.

As Professor Eileen Murphy from Queen’s University Belfast highlighted, ‘This study has revealed that, despite its location on the western extremity of Europe, Ireland – and certainly Dublin – was not isolated from the rest of the world during medieval times. Multiple strands of archaeological evidence indicate it was a vibrant port town throughout this era, a situation that brought the benefits of wealth but also facilitated the spread of infectious diseases.’

The paper outlining the results can be read for free at https://doi.org/10.1371/journal.pone.0209495.

This article appeared in CA 350.

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