Tuberculosis (TB) is one of the most common infections in the world. It is estimated that one-third of the world's population is currently infected with TB.1 The majority of those infected have latent tuberculosis (LTBI). Following infection with Mycobacterium tuberculosis (MTB), the organism replicates, most commonly in the lung as the portal of entry, then spreads through lymphatics to the blood stream where virtually any organ in the body can become infected. By the time this has occurred (2-3 months after infection) the host immune response develops in 95% of otherwise healthy persons and sets up granulomas that wall off the MTB organisms wherever they have settled. Many of these organisms remain viable in a dormant or latent state with the potential to reactivate at a later date when the immune system may weaken. The percentage of otherwise healthy persons who eventually reactivate varies from 5% to 15%; the younger the age at initial infection, the higher the risk of reactivation.2 Latent tuberculosis can be effectively treated with a completed course of therapy with either isoniazid or rifampin. Therefore, the Centers for Disease Control and Prevention and the American Thoracic Society have designated the identification and treatment of patients with LTBI as one of the major goals in eliminating TB from the United States.3 It is estimated that 10 to 15 million persons in the United States currently have LTBI.
Powell DA. Latent Tuberculosis Needs Attention. Arch Pediatr Adolesc Med. 2008;162(5):489-490. doi:10.1001/archpedi.162.5.489