Change in the prevalence of active pulmonary tuberculosis discovered at autopsy in black miners

The prevalence of active pulmonary tuberculosis at autopsy in two groups of Black miners who had died while working on the mines during the periods 1961-1963 and 1974-1978 was investigated. Radiographs had been taken regularly in both groups while they were alive to detect early tuberculous lesions. If any such lesions were found, the worker was excluded from the populations which were being studied. A highly significant secular decrease in the prevalence of active pulmonary tuberculosis was found. Possible explanations for this finding are discussed and it is concluded that there may be a decline in the incidence of tuberculosis in Blacks.