British Red Squirrels Remain the Only Known Wild Rodent Host for Leprosy Bacilli.

Eurasian red squirrels in the British Isles are the most recently discovered animal reservoir for the leprosy bacteria and . Initial data suggest that prevalence of leprosy infection is variable and often low in different squirrel populations. Nothing is known about the presence of leprosy bacilli in other wild squirrel species despite two others (Siberian chipmunk [], and Thirteen-lined ground squirrel []) having been reported to be susceptible to experimental infection with . Rats, a food-source in some countries where human leprosy occurs, have been suggested as potential reservoirs for leprosy bacilli, but no evidence supporting this hypothesis is currently available. We screened 301 squirrel samples covering four species [96 Eurasian red squirrels, 67 Eastern gray squirrels (), 35 Siberian chipmunks, and 103 Pallas's squirrels ()] from Europe and 72 Mexican white-throated woodrats () for the presence of and using validated PCR protocols. No DNA from leprosy bacilli was detected in any of the samples tested. Given our sample-size, the pathogen should have been detected if the prevalence and/or bacillary load in the populations investigated were similar to those found for British red squirrels.