Tuberculosis is transmitted from person to person by respiratory droplets. Although some people develop active tuberculosis disease after infection, almost all tuberculosis infections are asymptomatic and remain latent. Latent tuberculosis infection (LTBI) itself progresses to active disease in approximately 5% to 10% of infected persons. The rate of progression is much greater in immunocompromised individuals. The estimated 2 billion people living with LTBI represent a vast reservoir of potential cases of tuberculosis around the world. This reservoir of LTBI is therefore a major barrier to the ultimate control and elimination of tuberculosis. Strategies to combat tuberculosis in regions that are resource-rich aim, first, to identify and treat persons who have active disease; second, to find.
