Disseminated Mycobacterium ulcerans Infection in Wild Grasscutters (Thryonomys swinderianus), Cote d'Ivoire

Buruli ulcer is an infectious disease provoking chronic, disabling skin ulcers in mammals and humans. Buruli ulcer is caused by Mycobacterium ulcerans, an environmental mycobacterium synthesizing a toxin called mycolactone responsible for the pathogenicity. The reservoirs and the modes of transmission of M. ulcerans remain elusive, limiting the prophylaxis capabilities in rural areas in endemic countries. In Australia, several studies have demonstrated the probable role of possums as reservoirs. In Cote d'Ivoire, some studies have speculated on the potential role of grasscutters in the transmission cycle of M. ulcerans. In this study, we detected M. ulcerans-specific sequences in rectal contents and spleens collected in wild grasscutters hunted in Buruli ulcer-endemic area in Cote d'Ivoire, but not in farmed negative control animals and in domesticated animals, namely, pigs, goats, cattle, and dogs, living in close contact with the local population. Some grasscutters exhibited the same sequence pattern in the feces and spleen. These observations confirm the asymptomatic gut carriage of M. ulcerans in this mammal species. Moreover, these observations suggest the dissemination of M. ulcerans from the gut to the spleen in grasscutters. These observations suggest that, in some mammals, M. ulcerans is not only an inoculated pathogen but also a translocating invasive pathogen.