Photo Credit: Richard Carter (flickr)
Science

The red squirrel simply cannot catch a break

By Lizzie Harrett

The poor red squirrel can’t catch a break. Its American rival, the grey squirrel, has encroached upon much of it’s territory, with deforestation in the UK also majorly affecting its habitat. Now, new research adds to its list of woes and makes 2016 a bad year for both squirrels and humans alike, with a report finding that the bushy tailed rodents have tested positive for bacteria-causing leprosy.

Leprosy is a painful disease that causes the visual disfigurement of those infected. However, it is not generally thought-of as a disease that infects non-human animals. It has affected humanity for thousands of years, with individuals diagnosed in the past often tragically placed in leper colonies. Over 189,000 people worldwide had chronic leprosy in 2012, with half of these cases being in India. Fortunately, leprosy is curable with a multidrug antibiotic treatment and has not been evident in the UK for centuries, although around 200 cases are reported per year in the United States.

It was thought until recently that leprosy could only be transferred between humans, although previous research from the same team found evidence of leprosy in armadillos located in the United States. This new research further disproves this past assumption.

“It goes to show that once a disease has become extinct in humans, it could still exist in the environment if there was a suitable reservoir,” says study co-author Stewart Cole, director of the Global Health Institute at the Swiss Federal Institute of Technology in Lausanne.

The team analysed 110 red squirrel carcasses from across the the UK, with these split between visibly sick and not. Of the 97 seemingly healthy rodents, 21 tested positive and all 13 noticeably unwell squirrels had indicators of leprosy. Those who were sick had symptoms similar to those found in humans: skin lesions and patchy fur.

Interestingly, the strain found in some of the squirrels was similar to the one present in medieval England, which implies that the bacteria could have been doing the rounds in red squirrels for hundreds of years with little change. “One of the things we’ve never really understood about leprosy is how it can persist in populations at such low prevalence for such long periods of time,” says Richard Truman, a microbiologist at the National Hansen’s Disease Program who wasn’t involved with the work. The knowledge that leprosy bacteria remains in various animal populations could help reason why the disease has had sticking power in humans.

But you need not panic if you catch sight of fluffy-tailed rodent in your local park. Over 95 per cent of the population have a natural immunity to leprosy, and it is relatively non-contagious. Further to this and as previously stated, a course of antibiotics easily clears up the infection.

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