Tuberculosis caused by Mycobacterium bovis infection in a captive-bred American bullfrog (Lithobates catesbeiana)

BACKGROUND: Tuberculosis is widely known as a progressive disease that affects endothermic animals, leading to death and/or economical losses, while mycobacterial infections in amphibians are commonly due to nontuberculous mycobacteria. To the authors’ knowledge, this report describes the first case of bovine tuberculosis in a poikilothermic animal. CASE PRESENTATION: An adult female captive American bullfrog (Lithobates catesbeianus Shaw, 1802) died in a Brazilian aquarium. Multiple granulomas with acid-fast bacilli were observed in several organs. Identification of Mycobacterium bovis was accomplished by culture and PCR methods. The other animals from the same enclosure were euthanized, but no evidence of mycobacterial infection was observed. CONCLUSIONS: The American bullfrog was introduced in several countries around the world as an alternative husbandry, and its production is purposed for zoological and aquarium collections, biomedical research, education, human consumption and pet market. The present report warns about an episode of bovine tuberculosis in an amphibian, therefore further studies are necessary to define this frog species’ role in the epidemiology of M. bovis.