healthHealth and Medicine

The Viking Squirrel Trade May Have Brought Leprosy To The British Isles


Robin Andrews

Science & Policy Writer

Ancient, disease-spreading scumbags. Mark Caunt/Shutterstock

Squirrels may look adorable, but cuteness doesn’t mean you aren’t causing trouble. It’s well established that in the UK, the red squirrel has become an endangered species thanks to the habitat-stealing, virus-riddled invasive gray squirrel. New research, however, reveals that red squirrels have been harboring a dark past of their own.

The study, published in the Journal of Medical Microbiology, reveals that the crimson critters traded by Vikings hundreds of years ago were likely to have brought leprosy to the British Isles. This is based on new skeletal evidence, which shows that humans in the pre-Norman times could have been infected by strains that are known to affect squirrels.


Back then, around the 9th to 11th centuries, red squirrel meat and pelts were considered to be extremely valuable to Vikings. This explains why this squirrel-based leprosy has been identified in ancient human remains found in Denmark, Sweden, and now – according to the latest research led by the University of Cambridge – in Norfolk.

Leprosy – caused by the bacterium Mycobacterium leprae – is mostly found in warm, tropical countries. Despite this, human remains dating as far back as the 5th century reveal this strain of leprosy was prevalent in the region for several centuries.

This new study, however, makes the link between leprosy and red squirrels more explicit. Red squirrels in the UK today still suffer from a strain of leprosy, but curiously there have been no new documented cases of humans catching it off them.

This suggests that people could catch leprosy from red squirrels far more easily back then, but it’s not immediately clear why this would be the case. Red squirrels are neither consumed nor traded anymore, so perhaps it’s an issue of exposure. It could also be that the bacterial strain then was far more virulent than it is now, or that people’s immune systems have greatly strengthened over time - or, of course, because medical advances mean that it was eradicated over time through better detection and treatment.

Ick. Kateryna Kon/Shutterstock

Either way, leprosy, as you’d imagine, is not a particularly pleasant disease to contract.

Affecting the skin, nerves, and the membranes just beneath the skin, it causes ulcers, swelling, loss of facial hair, numbness, muscle paralysis, nosebleeds, potential blindness, and disfigurement through the body’s reabsorption of damaged appendages. It can take 20 years post-infection to manifest itself physically.

Although often considered to be a thing of the past, around 250 people each year contract it in the US. Another 250,000 around the world are also diagnosed on an annual basis.

It is, however, a fragile type of bacteria that quickly dies when not on a living animal. It’s only mildly infectious, and 95 percent of people have immune systems that would automatically prevent leprosy taking hold – so it’s not really something to be concerned about.


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