The red squirrels found originating in the forests of Britain have recently been found to carry certain strains of the Mycobacterium bacteria, which is responsible for leprosy. One of these strains dates back to as far as the medieval period, and is even responsible for a number of outbreaks in humans at that time!
The presence of this disease in squirrels had previously occurred in Scotland back in 2014, but this present occurrence is found to be more complex: not only is this more prevalent, but there are actually two strains presently infecting the squirrels!
Researchers analyzed about 110 deceased red squirrels in the UK and Ireland and found that indeed the squirrels were infected not only by the medieval-aged Mycobacterium leprae but also by the Mycobacterium lepromatosis strain.
The reason for these surprising findings is still unclear but it has been implied that the different strains may be affected by the small sample size being analyzed.
The first signs of leprosy among these red squirrels was observed when there were reports of these animals harboring lesions on their ears, snouts, and limbs. Further testing showed that they indeed have leprosy.
As for the possibility of affecting humans, Professor Anna Meredith from Royal (Dick) School of Veterinary Studies at the University of Edinburgh states that, “The discovery of leprosy in red squirrels is worrying from a conservation perspective but shouldn’t raise concerns for people in the UK.”
Professor Meredith and her co-authors of the study have also raised the possibility that these red squirrels can act as reservoirs for the disease due to their persistence in the environment in the current time. She adds that, “We need to understand how and why the disease is acquired and transmitted among red squirrels so that we can better manage the disease in this iconic species.”