Researchers who conducted tests to investigate what was causing the sores on red squirrels have found what is behind the mysterious marks. It turns out that some of these squirrels carry species of bacteria that cause leprosy in humans.
Ancient Infectious Disease
Leprosy, which is caused by Mycobacterium leprae and Mycobacterium lepromatosis bacteria, is an infectious disease that primarily affects the body's peripheral nerves, upper respiratory tract, eyes and skin.
The disease, also known as Hansen's disease, was once rampant in medieval Europe but dramatically declined by the end of the Middle Ages. Although leprosy is now largely controlled because of antibiotics, more than 200,000 new cases of the disease is still reported each year.
Leprosy-Related Pathogens In Red Squirrels
For the study published in journal Science on Nov. 11, researchers ran genetic screening and blood tests on cadavers of more than 100 red squirrels from England, Scotland and Ireland, and found that all 25 red squirrels from Brownsea Island in England harbor the bacterium Mycobacterium leprae, the oldest leprosy-linked pathogen attributed for outbreak of the disease in medieval Europe. Some squirrels also tested positive for Mycobacterium lepromatosis.
"Using genomics, histopathology, and serology, we found M. lepromatosis in squirrels from England, Ireland, and Scotland, and M. leprae in squirrels from Brownsea Island, England. Infection was detected in overtly diseased and seemingly healthy animals," the researchers wrote in their study.
Some of the animals even showed signs of the disease which include swelling in the ears, eyes feet and snouts as well as damage to nerve endings.
Animal Reservoirs Of Leprosy
Study researcher Charlotte Avanzi, from the Swiss Federal Institute of Technology, said that their findings came as a surprise since no humans have contracted leprosy in the British Isles for centuries. She said that the results indicate that the number of non-human reservoirs of leprosy is much higher compared with what is previously believed.
Avanzi said the study can be of particular interest in countries where the disease is still endemic in humans such that some of the new cases may be explained by the presence of an animal reservoir.
Risk Of Red Squirrels Spreading Leprosy
Doctors used to think that people can only catch leprosy from other people but in 2011, researchers showed that armadillos in southern U.S were likely infecting people.
Researchers of the new study said that the chances of red squirrels transmitting leprosy to people are low mainly because contact between the animals and humans in the UK are limited.
