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.

Bovine tuberculosis in the United States and Puerto Rico: a laboratory summary.

Mycobacteria were isolated from 14.3% of the tissues submitted to the National Veterinary Services Laboratories over a 5-year period (July 1, 1972, to June 30, 1977). The isolates were identified by drug susceptibility, and biochemical and serologic tests. Mycobacterium bovis isolated from tissues of cattle originating in 32 states and Puerto Rico accounted for 78% of the acid-fast isolations. Of the Mycobacterium bovis isolates, 4% were from tissues in which no microscopic tuberculous granulomas were observed on examination of tissue sections. Of the 119 Mycobacterium avium isolates, 18 were serotype 1, 44 were serotype 2, and 45 isolates represented 12 other serotypes.