Human tuberculosis caused by Mycobacterium bovis in the United States, Latin America and the Caribbean

Human tuberculosis (TB) caused by Mycobacterium bovis appears to be rare in most of the region of the Americas, although some localities have reported an unusually high prevalence of M. bovis among human TB cases (e.g., San Diego, CA, USA; parts of Mexico). As surveillance data are lacking in many countries, there is substantial uncertainty regarding actual incidence. M. bovis is most often not identified, as the diagnosis of TB is made by smear microscopy alone or using egg-containing culture media lacking pyruvate. Where human M. bovis cases have been studied in the region, they appear to be associated with ingestion of unpasteurized dairy products, or with airborne acquired infection in animal keepers and meat industry workers from countries where bovine TB remains a problem. Human-to-human transmission of M. bovis does occur, but appears to account for a very small proportion of cases. Efforts to eradicate M. bovis in humans in the Americas should therefore be directed at eradicating the disease in cattle, increasing pasteurization of dairy products and providing education about the dangers of consuming unpasteurized dairy products.