First record of tuberculosis lesions in zooarchaeological samples of otariid pinnipeds. New aspects of the pre-european origin of human tuberculosis in South America and dissemination mechanisms of Mycobacterium pinnipedii in the Southern Hemisphere

In 2003 Mycobacterium pinnipedii was described as responsible for producing tuberculosis (TB) in living otariid pinnipeds from Argentina and Australia. It is the only member of marine origin within the Mycobacterium tuberculosis Complex (MTBC), which also affects other domestic and wild mammals, and humans. Based on several pre-Columbian records of human tuberculosis in South America, in 2010-2011 a new hypothesis about the origin of this zoonosis through otariid pinnipeds arose. In 2014, this hypothesis was confirmed based on the study of ancient DNA from three mummies (700-1,000 years BP) of the Chiribaya culture (Peru). Since there were no records of TB bone lesions in zooarchaeological samples of otariid pinnipeds from South America and the rest of the world, our study aimed at examining zooarchaeological samples of pinnipeds from coastal sites of the Beagle Channel (Tierra del Fuego, Argentina), being the oldest Túnel I (6,400-4,300 years BP). A total of 4,138 vertebrae were analyzed, of which 0.46 % showed lesions compatible with TB. In addition, we propose a new hypothesis on possible mechanisms of Mycobacterium pinnipedii dissemination that would explain the transmission routes to the different otariid pinniped species of the Southern Hemisphere. Mycobacterium pinnipedii is one of the most aggressive mycobacteria of the MTBC and of high risk for humans.