Leprosy is widely known as a highly contagious disease. Caused by the acid-fast bacilli Mycobacterium leprae, it has been found recently in endangered red squirrels across the British Isles. But experts claim that what the red squirrels have are not infectious to humans.

A group of researchers from the University of Edinburgh found two types of bacteria infecting the red squirrels in the UK, and they are the same bacteria that cause leprosy in humans and plagued the region during the Middle Ages. According to the study, these strains probably developed from a common ancestor about 27,000 years ago. Squirrels could transmit the disease to humans, but the chances are very low.

"We should be even more concerned about the squirrels now and not frightened of them," Prof. Anna Meredith, one of the leaders of the study, emphasized. "We have found it is widespread all over the United Kingdom and Ireland, but we don't want people to be alarmed. It has been around a long time and there have been no human cases for hundreds of years."

Red squirrels are endangered in Britain, and leprosy is eyed as one of the reasons behind the population decline. Aside from lepsory, the invasion of gray squirrels, which were found to be immune from the disease, has also aggravated their situation, tightening the food and space competition within their habitat. Researchers are currently finding ways to help save their population.

The discovery of the leprosy strain on red squirrels was verified through an experiment using 100 dead specimens collected from Scotland, England, and Ireland. DNA analysis was used to trace the leprosy bacteria.

Read here: Paper on Leprosy Virus Discovery with British Red Squirrels (Sciurus vulgaris)