The transmission of tuberculosis in the light of new molecular biological approaches.

This review briefly summarises the recent achievements in tuberculosis epidemiology associated with the introduction of molecular methods, and considers the implications of these methods for the understanding of occupational tuberculosis transmission. Special attention is paid to the relative contribution of recently transmitted tuberculosis; risk factors for recent transmission; and the occurrence and frequency of exogenous reinfection. There is a need for occupational epidemiological studies, which should combine the methods of "classical" epidemiology with those of molecular epidemiology.