Transmission of Mycobacterium ulcerans to the nine-banded armadillo

Animal models for Mycobacterium ulcerans infections (Buruli ulcer) include guinea pigs, rats, and mice, but each has limitations in replicating the spectrum of human disease. Here, 19 adult nine-banded armadillos were inoculated intradermally with M. ulcerans. Injection sites were examined and skin samples obtained for histologic and microbiology studies. Necropsies were conducted to assess systemic involvement. In group 1 (n = 4), 2 animals developed progressive skin ulcers with undermined borders at the injection sites within 6-10 weeks. Biopsies showed features similar to human disease including extensive necrosis in the deep dermis and subcutaneous fat, mixed cellular infiltrates, and acid-fast bacilli (AFB). In group 2 (n = 15), 5 animals developed progressive skin ulcers, 3 had evanescent papulo-nodules, 3 died shortly after inoculation of unknown causes, and 4 showed no signs of infection. Lesion samples from 3 animals with progressive ulcers were culture positive for AFB. Our findings indicate that nine-banded armadillos are susceptible to M. ulcerans and may develop cutaneous lesions that closely mimic Buruli ulcer.