Scientists have discovered that squirrels are carriers of leprosy, and that they may have served as a reservoir of bacteria for the disease.
While leprosy was until recently considered a disease affecting almost exclusively humans (and certain species of armadillo), scientists have discovered that red squirrels in the UK are also susceptible.
published in the scientific journal Science, this study, carried out by an international team of researchers led by Pr Anna Meredith of the University of Edinburgh, required the DNA analysis of 110 squirrels in England, Scotland and Ireland.
Microbiologists have discovered two types of bacteria causing leprosy in these squirrels. The first, called Mycobacterium leprae, was discovered in squirrels living on the island of Brownsea, off the coast of southern England, and whose strain is very similar to that discovered in a skeleton of a leper buried in Winchester (70 km from Brownsea) … 730 years ago!
A reservoir for disease
The other strain, Mr. Lepromatosis, has been found in squirrel populations living in the rest of the UK and Ireland. Mr. Lepromatosis is a strain of leprosy discovered only recently (in 2008) and the disease attached to it is mainly found in Mexico and the Caribbean islands.
Moreover, the comparison between the strain of M. Lepromatosis discovered in squirrels and that of two humans from Mexico has enabled scientists to determine a much older common ancestor this time: 27,000 years.
According to the scientists, this study shows that animals could be a reservoir for leprosy bacteria, preventing an eradication of the infection.
This study therefore raises a question: if squirrels can be leprosy reservoirs, are other animals also in this case? While human cases of leprosy are virtually non-existent in Western countries today, this infection continues to strike in developing countries.
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