Molecular epidemiology of tuberculosis.

Despite the almost 50 yrs since the introduction of curative antituberculosis drugs, Mycobacterium tuberculosis continues to exert an enormous toll on world health, and tuberculosis remains the world's leading cause of death due to a single infectious agent. This has stimulated research efforts into finding new tools to tackle the continuing tuberculosis pandemic. One of the few successes to date has been the development of a new discipline, molecular epidemiology. This has added a further dimension to the classical epidemiology of tuberculosis and enhanced understanding of how M. tuberculosis continues to be successfully transmitted within populations. In the process, inadequacies in tuberculosis control programmes have been identified, helping accumulate resources for their improvement. Other technologies, based on knowledge of the complete genome sequence of M. tuberculosis, which will provide newer tools for probing the epidemiology of tuberculosis, are now emerging. In spite of these advances, tuberculosis continues to remain a devastating infectious disease, disproportionately impacting on the world's poorest countries. The future challenge for molecular epidemiology is to provide better understanding of the transmission dynamics of tuberculosis in these settings and to stimulate the implementation of control measures on a more global scale.