The skull of a woman found in a garden in Hoxne. Facial lesions around her nose and palate were recently confirmed through ancient DNA analysis as having been caused by leprosy. The strain of the bacterium was the same as that found in modern squirrels from the south of England. (Photo: Sara Inskip)

The association between rats and the outbreak of the Black Death is notorious, but a new study, by the Universities of Cambridge and Surrey, suggests that rats are not the only rodents who may have had an adverse impact on medieval British health. Ancient DNA analysis of an Anglo-Saxon woman from East Anglia, afflicted with leprosy, has indicated that there could be a link between the spread of the disease and squirrels. The discovery adds to the already comparatively high number of medieval leprosy cases from the region.

Sometime between 1960 and 1990, the skull – from a young to middle-aged adult female – was recovered from a garden in Hoxne, Suffolk, and subsequently stored at Diss Museum in Norfolk. There it remained until it was first analysed in 1996 by the Suffolk County Council Archaeological Service. It was during this examination that pathological lesions on the nose and palate were first noted. While these lesions were consistent with leprosy (or Hansen’s disease) several other diseases are known to present with similar characteristics, and without the rest of the skeleton, the individual could not definitively be diagnosed.

Recently, with ancient DNA analysis now more reliable and effective than ever before, it was decided that the technique could be used to confirm whether or not this was indeed a rare case of leprosy. The skull was not analysed for the individual’s personal DNA, however, but instead for the DNA of Mycobacterium leprae, the bacterium that causes leprosy.

(Photo: Peter Trimming, Wikimedia Commons)

The results showed not only that M. leprae was present, but also that it was the same strain of the bacterium – subtype 3I – as was found in living squirrels from the south of England. This strain has also been found in skeletal remains from medieval Denmark and Sweden, as well as remains of a 6th-century man from Great Chesterford. The research team think that these links could suggest that at some point this strain of the disease may have been transferred from squirrels to humans or vice versa. That Scandinavia and East Anglia had strong trade connections during this period, one of which was the trading of squirrel pelts and meat, is an intriguing additional aspect.

‘Research has already established that leprosy can be passed from armadillos to humans, so that it may also come from squirrels is an interesting idea,’ said Dr Sarah Inskip, the lead author of the paper in The Journal of Medical Microbiology that published the results. ‘It is questionable how long the bacteria could have survived on fur or meat, but it is notable that squirrels were also sometimes kept as pets.’

This article appeared in CA 337.

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