A study of archaeological sites in Winchester, England, has revealed that red squirrels served as a host for Mycobacterium leprae strains that caused leprosy in people.
Leprosy is one of the oldest recorded diseases in human history and is still prevalent to this day in Asia, Africa, and South America.
It has previously been suggested that the extensive trade of red squirrel fur, greatly valued during medieval times, could have contributed to the leprosy epidemic in medieval Europe.
The results of the study, published in the journal Current Biology, studied 25 human and 12 squirrel samples from two medieval sites in Winchester.
During this period, the city had strong connections to the fur trade and housed the leprosarium, a hospital that treated people with Hansen’s disease (leprosy) caused by Mycobacterium leprae bacteria.
Verena Schuenemann of the University of Basel in Switzerland, said: “With our genetic analysis we were able to identify red squirrels as the first ancient animal host of leprosy.”
The study found that the medieval red squirrel strains were more closely related to human strains in Winchester, rather than to modern squirrel strains from England – suggesting an independent circulation of Mycobacterium leprae strains.
“Our findings highlight the importance of involving archaeological material, in particular animal remains, into studying the long-term zoonotic potential of this disease, as only a direct comparison of ancient human and animal strains allows reconstructions of potential transmission events across time,” says Sarah Inskip of the University of Leicester, UK, a co-author on the study.
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Sources : Current Biology, Urban, Blom, and Avanzi et al.: “Ancient Mycobacterium leprae genome reveals medieval English red squirrels as animal leprosy host.” https://www.cell.com/current-biology/fulltext/S0960-9822(24)00446-9
