Molecular epidemiology of TB: challenging dogmas and asking new questions.

Traditional epidemiological methods provide insight into the dynamics of diseases such as tuberculosis. These traditional techniques have limitations and rely on a number of assumptions. The application of molecular techniques to the study of epidemiology has allowed us to gain new insights into the biology of the organism Mycobacterium tuberculosis and the dynamics of the disease. We have been enabled to push the limits of understanding of the epidemiology of this disease, allowing us to challenge the old clinical dogmas, ask new questions, design new strategies, and measure the efficacy of such new interventions to combat this age-old scourge. Among the dogmas challenged are that infection outside the home is commonplace, so-called relapse cases may in fact be largely reinfection, and active transmission may be more common than previously thought and reactivation disease relatively uncommon. These findings alone demand urgent attention and the design of optimal intervention strategies to reduce the burden of disease.