Red squirrels carrying strain of human leprosy - people warned to stay away
Red squirrels are carrying human leprosy and people have been warned to stay away from the animals to minimise the risk of catching the disease.
One of the strains – which is affecting squirrels on Brownsea Island, off the south coast of Dorset in the UK – shares close similarities with that responsible for outbreaks of the disease in medieval Europe.
Researchers tested 25 samples from red squirrels on the island and found that all were infected with the bacteria Mycobacterium leprae, though not all showed signs of the disease. Those that did had swelling and hair loss on the ears, muzzle and feet.
Until now it was thought that the animals only carried an animal version. Human leprosy has been found in red squirrels in other parts of England, Scotland and Ireland but of a different strain which has never infected anyone in Britain yet does elsewhere.
Although the risk to humans is small, scientists at the University of Edinburgh say people should avoid physical contact and wash hands thoroughly to minimise the risk.
“Taking sensible precautions such as avoiding physical contact with wild animals and washing your hands before eating will further minimise any risk,” said Professor Anna Meredith, of the University of Edinburgh’s Royal School of Veterinary Studies.
“The discovery of leprosy in red squirrels is worrying from a conservation perspective but shouldn’t raise concerns for people in the UK.
“The bacteria that cause leprosy cannot survive outside the body and evidence shows that 95 per cent of all people are naturally unable to get leprosy, even if they are exposed to the bacteria that causes it.
“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.”
One of the papers lead authors Dr Andrej Benjak said it was important to monitor the disease in Britain, as part of the WHO's global Leprosy Surveillance Programme.
"Leprosy has not been detected in the UK in decades, though we cannot exclude the possibility of rare, unreported or misdiagnosed cases that originated within the UK," he said.
The red squirrel is already endangered because of spread of grey squirrels and conservationists are concerned that the disease spread could cause further population decline.
The new bacteria shares close similarities with a strain discovered in the skeleton of a leprosy victim buried in Winchester 730 years ago.
Scientists, who collected samples of bacteria from dead squirrels, say their findings suggest that leprosy has affected red squirrels on Brownsea Island for centuries.
“It was completely unexpected to see that centuries after its elimination from humans in the UK, Mycobacterium leprae causes disease in red squirrels,” said Professor Stewart Cole, of the École Polytechnique Fédérale de Lausanne, co-author of the study.
“This has never been observed before.”
However scientists say their findings suggest that animals could be a reservoir for bacteria and may be thwarting attempts to eradicate the disease in other countries.
Angela Cott, National Trust General Manager for Brownsea Island, said: "Brownsea's wild red squirrel population has been living with leprosy for at least four decades.
“But by working with the University of Edinburgh and Dorset Wildlife Trust, we hope to understand how best to look after Brownsea's wild red squirrels. Brownsea Island remains a spectacular place for people to see wildlife."