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 2016.1 In that same year, there were 9287 new cases in the United States—the lowest number of TB cases on record.2
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%,3 although in the United States it is only about 5%.4 The proportion of those with LTBI who will develop active disease is estimated at 5% to 10% and is highly variable depending on risks.4
In the United States, about two-thirds of active TB cases occur among those who are foreign born, whose rate of active disease is 14.6/100,000.2 Five countries account for more than half of foreign-born cases: Mexico, the Philippines, India, Vietnam, and China.2
Who should be tested?
A major public health strategy for controlling TB in the United States is targeted screening for LTBI and treatment to prevent progression to active disease. The US Preventive Services Task Force (USPSTF) recommends screening for LTBI in adults age 18 and older who are at high risk of TB infection.4 This is consistent with recommendations from the Centers for Disease Control and Prevention (CDC), although the CDC also recommends testing infants and children at high risk of infection, as well as all those at high risk for progression to active disease (TABLE 14-6).5