A team of researchers from several universities in Britain have proposed that leprosy may have spread to Britain by way of Scandinavian migration during the Migration Period:

"An international team, including archaeologists from the University of Southampton, has found evidence suggesting leprosy may have spread to Britain from Scandinavia.

The team, led by the University of Leiden, and including researchers from Historic England and the universities of Southampton, Birmingham, Surrey, and Swansea, examined a 1500 year old male skeleton, excavated at Great Chesterford in Essex, England during the 1950s.
The bones of the man, probably in his 20s, show changes consistent with leprosy, such as narrowing of the toe bones and damage to the joints, suggesting a very early British case.

Modern scientific techniques applied by the researchers have now confirmed the man did suffer from the disease and that he may have come from southern Scandinavia."

Read more: "Ancient skeleton shows leprosy may have spread to Britain from Scandinavia" at Phys.org