Tuberculosis

One third of the world population has Mycobacterium tuberculosis infection (1). Despite recent progress in the United States, tuberculosis infection remains prevalent in immigrants, immunosuppressed per sons, and other high-risk groups (3). Latent tuberculosis infection (LTBI) is the most prevalent form of tuberculosis in the United States (2). LTBI can progress to active tuberculosis disease, especially in individuals with a suppressed cell-mediated immunity. Active tuberculosis disease in immunosuppressed patients can be difficult to diagnose and can progress to disseminated forms of tuberculosis disease associated with high mortality (4). New methods of diagnosing tuberculosis disease have entered practice in recent years (5), but the diagnosis of LTBI can be challenging in some high-risk populations (6, 7). The introduction of directly observed therapy with firstline antituberculous regimens (8) was an important advance in therapy, but multidrug-resistant tuberculosis (MDR-TB) and the extensively resistant form of MDR-TB remain significant threats to international and local tuberculosis control efforts (9, 10).