Medieval squirrels may have ‘helped spread leprosy’ 

In the middle Ages, squirrels were sometimes kept as pets. Keystone/Paul Zinken

Squirrels could have played a role in the spread of leprosy in the Middle Ages. Researchers at the University of Basel have identified the pathogen that caused the disease in medieval squirrel bones, according to a study published on Friday.  

However, it is not yet clear exactly what role the animals played in the spread and transmission of leprosy, as study leader Verena Schünemann from the University of Basel told the Keystone-SDA news agency. “We don’t know whether the squirrels infected the humans or vice versa.”  

However, the leprosy bacteria (Mycobacterium leprae) that the researchers were able to detect in the medieval squirrel bones from England are closely related to leprosy bacteria found in human bones from the same period and region. The researchers published this result in the scientific journal Current Biology.  

According to Schünemann, these findings about leprosy in the Middle Ages are also of great importance for today. To date, it has not been possible to eradicate the disease completely: around 200,000 people contract the disease every year. “How the disease spreads is not yet fully understood,” said Schünemann.  

Animals as hosts of leprosy have received little attention. “However, animals may be important for understanding the persistence of the disease,” explained Schünemann. Research into the history of so-called zoonoses, i.e. diseases which can spread from animals to humans, could provide important insights in this regard.  

For their study, the researchers examined the remains of twelve red squirrels and 25 humans at the archaeological site in Winchester (UK). The city was known for a so-called leprosarium, a hospital for leprosy patients.  

It also had links to the fur trade. There was therefore an exchange between leprosy patients and squirrels, as coats were made from squirrel fur in the Middle Ages, as the researchers explained in the study. In addition, squirrels were sometimes kept as pets during this period.  

Adapted from German by DeepL/kc

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