Research shows that squirrels spread leprosy in England in the 10th and 11th centuries

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Research suggests that leprosy spread between red squirrels and humans in England between the 10th and 11th centuries.

Evidence collected at two archaeological sites in the medieval city of Winchester suggests that red squirrels may have historically been a host for Mycobacterium leprae – the bacteria that causes leprosy in humans.

Researchers say that while there is evidence that this disease was passed to humans from infected armadillos, it is the first time scientists have found evidence that leprosy circulated between humans and rodents in medieval England.

Modern red squirrels also appear to carry strains of the leprosy bacteria, but the team said these rodents pose no threat to people in Britain.

Despite popular myths that leprosy can spread from person to person through physical contact, the infection is not highly contagious.

The disease is believed to be spread mainly through coughing or sneezing.

Dr. Sarah Inskip, a bioarchaeologist at the University of Leicester, said: “Very few people are susceptible to leprosy these days and you would have to have prolonged contact with an infected animal.

“There aren’t many left today (Britain has only 160,000 native red squirrels), so the chances are extremely slim.”

Leprosy is one of the oldest recorded diseases in human history, which targets the nervous system and causes swelling under the skin.

Although rare, the so-called biblical disease still exists and, according to the World Health Organization, approximately 208,000 people around the world suffer from leprosy, especially in Asia and Africa.

Leprosy can be cured with antibiotics, but if left untreated it can lead to disfigurement, disability and blindness.

For the study, published in the journal Current Biology, the researchers analyzed 25 human and 12 squirrel bone samples collected at the Winchester sites.

Genetic analysis showed that M. leprae was present in samples from both humans and squirrels, indicating that the infection circulated between humans and rodents in the Middle Ages.

Verena Schuenemann, professor of archaeological sciences at the University of Basel in Switzerland, said the medieval red squirrel species found is more closely related to medieval human strains from Winchester than to strains isolated from infected modern red squirrels.

She added: “Overall, our results indicate an independent circulation of M. leprae strains between humans and red squirrels during the Middle Ages.”

Because Winchester was known for its leper hospitals and connections to the fur trade, researchers speculate that this is how the transfer occurred.

Dr. Inskip said: “We chose Winchester because the sites themselves have squirrel bones.

“There are hand and foot bones (recovered from the sites) – that’s what we see when people process squirrel skin.

“So that gives us an idea of ​​how people at that specific location interacted with the squirrels.”

Squirrel fur was widely used in the Middle Ages to decorate and line clothing.

There is evidence that many have also captured wild squirrels as kits in the wild and raised them as pets.

Dr. Inskip said: “We forget how many people have interacted with squirrels in the past and how much they have been part of people’s lives, and historical sources highlight that very nicely.

“This is very important to change people’s perception that leprosy is a disease that only affects humans.”

She added: “There is a long history of sharing diseases between humans and animals, and they continue to have a major impact on us.

“In the wake of Covid-19, animal hosts are now becoming a focus for understanding the appearance and persistence of disease.”