The role of red squirrels in leprosy dynamics in the United Kingdom: a critical review

In the United Kingdom, the declining population of the red squirrel, the acknowledged historical reservoir for zoonotic Mycobacterium leprae leprosy, is thought to have been behind the decline in leprosy. However, remaining red squirrels are mainly plagued by Mycobacterium leprae, questioning their historical role in zoonotic M. leprae leprosy dynamics. To resolve this issue, forthcoming paleomicrobiology studies will address the M. leprae complex as a whole; investigating the remains of squirrels buried for eight centuries, and burrowing animals imported in the United Kingdom from the British Empire countries between the 16th and 19th centuries; also looking at the situation in continental Europe, to gain a more comprehensive view of the historical zoonotic dynamics of leprosy in the United Kingdom and Europe. The results may indicate that the declining red squirrel population is no more than a red herring, obscuring a broader decline in leprosy.