Overseas screening for tuberculosis in U.S.-bound immigrants and refugees

In 2007, a total of 57.8% of the 13,293 new cases of tuberculosis in the United States were diagnosed in foreign-born persons, and the tuberculosis rate among foreign-born persons was 9.8 times as high as that among U.S.-born persons (20.6 vs. 2.1 cases per 100,000 population). Annual arrivals of approximately 400,000 immigrants and 50,000 to 70,000 refugees from overseas are likely to contribute substantially to the tuberculosis burden among foreign-born persons in the United States.

The Centers for Disease Control and Prevention (CDC) collects information on overseas screening for tuberculosis among U.S.-bound immigrants and refugees, along with follow-up evaluation after their arrival in the United States. We analyzed screening and follow-up data from the CDC to study the epidemiology of tuberculosis in these populations.

From 1999 through 2005, a total of 26,075 smear-negative cases of tuberculosis (i.e., cases in which a chest radiograph was suggestive of active tuberculosis but sputum smears were negative for acid-fast bacilli on 3 consecutive days) and 22,716 cases of inactive tuberculosis (i.e., cases in which a chest radiograph was suggestive of tuberculosis that was no longer clinically active) were diagnosed by overseas medical screening of 2,714,223 U.S.-bound immigrants, representing prevalences of 961 cases per 100,000 persons (95% confidence interval [CI], 949 to 973) and 837 cases per 100,000 persons (95% CI, 826 to 848), respectively. Among 378,506 U.S.-bound refugees, smear-negative tuberculosis was diagnosed in 3923 and inactive tuberculosis in 10,743, representing prevalences of 1036 cases per 100,000 persons (95% CI, 1004 to 1068) and 2838 cases per 100,000 persons (95% CI, 2785 to 2891), respectively. Active pulmonary tuberculosis was diagnosed in the United States in 7.0% of immigrants and refugees with an overseas diagnosis of smear-negative tuberculosis and in 1.6% of those with an overseas diagnosis of inactive tuberculosis.

Overseas screening for tuberculosis with follow-up evaluation after arrival in the United States is a high-yield intervention for identifying tuberculosis in U.S.-bound immigrants and refugees and could reduce the number of tuberculosis cases among foreign-born persons in the United States.