Screening for tuberculosis: Updated recommendations.

Tuberculosis (TB) remains a significant public health problem worldwide with an estimated 10.4 million new cases and 1.7 million deaths having occurred in 2016. In that same year, there were 9287 new cases in the United States--the lowest number of TB cases on record. TB appears in one of 2 forms: active disease, which causes symptoms, morbidity, and mortality and is a source of transmission to others; and latent TB infection (LTBI), which is asymptomatic and noninfectious but can progress to active disease. The estimated prevalence of LTBI worldwide is 23%, although in the United States it is only about 5%. The proportion of those with LTBI who will develop active disease is estimated at 5% to 10% and is highly variable depending on risks. In the United States, about two-thirds of active TB cases occur among those who are foreign born, whose rate of active disease is 14.6/100,000. Five countries account for more than half of foreign-born cases: Mexico, the Philippines, India, Vietnam, and China.