Bovine tuberculosis in humans in Ontario. The epidemiologic features of 31 active cases occurring between 1964 and 1970.

Abstract

During the period 1964 to 1970, 31 cases of tuberculosis in humans due to Mycobacterium bovis were reported in Ontario, representing 0.5 per cent of all bacteriologically proved cases. There were no cases in children. Most cases were the result of infection that occurred either in Ontario many years ago or in other countries. Seventy-five per cent of the patients were 40 or more years old, and 60 per cent were foreign-born, of whom at least 50 per cent were infected before arriving in Canada. Of the 31 patients, 13 had pulmonary disease and 18 had extrapulmonary disease, which in 12 involved the genitourinary tract. Probable instances of transmission from animals to man, man to animal, and man to man were observed. Because of the persistent reservoir of infection in the human population, cases of tuberculosis due to Mycobacterium bovis will continue to occur for many years to come, and for both epidemiologic and clinical reasons must be differentiated from cases due to Mycobacterium tuberculosis. Bovine tuberculosis in animals has not been eradicated, and surveillance programs must continue.