Squirrel Leprosy Experiment To Take Place In Southern England

304 Squirrel Leprosy Experiment To Take Place In Southern England
The native red squirrels in the U.K. have been decimated by the arrival of the invasive grey squirrel. Neil Burton/Shutterstock

An island in southern England is to be used for a squirrel leprosy experiment. Only discovered to be infecting red squirrels in 2014, the project aims to use the island setting as a perfect natural laboratory in which to study how the disease impacts the creatures in the wild. Symptoms of the disease include swelling and the loss of fur from their face, ears, and feet, and it is hoped that by understanding how the disease spreads, then something can be done to prevent more infection.

The researchers, from the University of Edinburgh and working with the National Trust and Dorset Wildlife Trust, suspect that the disease, caused by the bacterium Mycobacterium lepromatosis, has actually been present in the population for some time now, though it has only recently been detected. Brownsea Island, on which the experiments will take place, is open to the public and will remain so. Despite the bacteria causing the disease in the squirrels being closely related to that which causes the most common strain of leprosy in humans, the biologists say that the risk to people visiting is “negligible.”


Previously, the main threat to the survival of the native red squirrels in the U.K. has been from the invasive eastern gray squirrel. First introduced into the country from North America in 1876 when a pair were released in Cheshire, northwest England, the novelty of the animals soon became fashionable within Victorian circles. Five million of the creatures later, and they are now deemed a very serious threat to the native reds, whom the grays outcompete.

Larger and more aggressive, they easily challenge the smaller reds and beat them to food and nesting spots. But they also harm the native species in another way: they carry squirrelpox. While the virus is not deadly to the grays, if left untreated the disease has a 100 percent mortality rate among the reds. This, coupled with being outcompeted, has hammered the red squirrel population so that now only between 120,000 and 140,000 of them remain in the U.K., of which 75 percent reside in Scotland.

It is vital that the newly recognized leprosy found in the red squirrels is, therefore, understood before it can seriously impact their numbers further. The project aims to monitor the 200 or so red squirrels that live on the isolated island, by catching them in humane traps and then testing them for the bacterium and other health problems. They will then see how the disease spreads among the squirrels and what, if any, impact it has. 


  • tag
  • leprosy,

  • squirrel virus,

  • U.K.,

  • red squirrel,

  • grey squirrel