Researchers have found out why British red squirrels have an increasing number of sores. The discovered that the animals carry bacteria that caused leprosy in humans during medieval times. This result was very surprising considering that it was thought only humans could suffer from the disease.
For their study, researchers led by Charlotte Avanzi, a doctoral assistant at the Swiss Federal Institute of Technology in Lausanne, analyzed over 100 bodies of red squirrels gathered from the British Isles, including Ireland and Scotland. The species, scientifically known as Sciurus vulgaris are predominant throughout Eurasia.
After performing various genetic screening and blood tests on the cadavers, they discovered that 25 squirrels, all from the Brownsea Island in England, were carriers of the Mycobacterium leprae. This is the oldest type of pathogen associated with leprosy as it was responsible for outbreaks during Medieval England and all over Europe. The affected squirrels had skin lesions and swelling of the ears, snouts, lips, eyelids and other extremities. These symptoms are similar to those experienced by humans.
Although no other squirrels had the same bacteria, others were found to have a related pathogen, Mycobacterium lepromatosis, which also causes leprosy. The study’s finding, published in the journal Science, reveals that a pathogen can persist in an environment despite being cleared from humans.
Although humans have a low chance of developing leprosy from these squirrels because of limited contact, the persistence of the pathogen in animals can be a fact of interest for developing countries where the disease is still endemic. A small role might be played by infected animals.
The modern name of leprosy is Hansen’s disease. Around the world, almost 220,000 people are infected every year, most in developing nations. However, even developed countries like the U.S still see between 150 and 200 cases of leprosy every year. A study from May 2016 revealed that the total number cases of leprosy in the UK between 2003 and 2012 were 139.
Researchers need to perform a further analysis in order to establish the exact origin of the pathogen and how the red squirrels in Britain managed to get infected with it. It’s unclear if either the squirrels infected humans in medieval times or the people infected the squirrels.
Image source: Geograph