Leprosy ‘may have circulated between red squirrels and humans’, new research shows

Squirrel fur was used to trim clothes during the medieval period, which helps explain how humans came in contact with the animals. Photo: Getty

Nilima Marshall

Leprosy may have spread between red squirrels and humans in medieval England, research suggests.

Evidence gathered from two archaeological sites in Winchester suggest red squirrels may have been a host for Mycobacterium leprae – the bacteria that causes leprosy in people – in the past.

Modern red squirrels have also been found to carry strains of the leprosy bacteria, but the team said that these rodents do not pose a threat to people in the UK.

Despite myths about leprosy leaping from person to person, the infection is not highly contagious today.

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

“There are not many of them around today either (Britain has just 160,000 native red squirrels), so the chances are extremely low.”

Leprosy is one of the oldest recorded diseases. It targets the nervous system and causes swelling under the skin. It can be cured using antibiotics but if left untreated, can lead to deformity, disability and blindness.

Although rare, the so-called biblical disease still exists and according to the WHO, around 208,000 people have leprosy around the globe, mostly in Asia and Africa.

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

Genetic analysis revealed Mycobacterium leprae to be present in both human and squirrel samples, indicating the infection was circulating between people and the rodents in the Middle Ages.

Verena Schuenemann, a professor at the University of Basel, said the medieval red squirrel strain recovered is more closely related to medieval human strains than to strains isolated from infected modern red squirrels.

As Winchester was known for its leprosy hospitals and connections to the fur trade, the researchers speculate this is how transmission may have occurred.

Squirrel fur was widely used on garments during the medieval period. Evidence suggests people also trapped wild squirrels and raised them as pets.

Dr Inskip said: “We forget how much people may have interacted with squirrels in the past and how much they would have been a part of people’s lives.

“There is a long history of sharing diseases between humans and animals. They continue to have a big impact on us.”