High TB Rates Among Immigrants To U.S. Highlight Need For Improved Screening, Study Says

Main Category: Infectious Diseases / Bacteria / Viruses
Also Included In: Respiratory / Asthma;  Public Health
Article Date: 24 Jul 2008 - 9:00 PDT

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Immigrants arriving in the U.S. from Southeast Asia, sub-Saharan Africa and parts of Latin America have high rates of active or latent tuberculosis, highlighting a need for improved screening of the disease, according to a CDC study published Wednesday in the Journal of the American Medical Association, Reuters reports (Stern, Reuters, 7/22).

For the study, CDC researcher Kevin Cain and colleagues analyzed data on TB among U.S. immigrants from 2001 to 2006. The researchers found that immigrants from sub-Saharan Africa and Southeast Asia were at highest risk for the disease, with TB incidence of approximately 250 cases per 100,000 people among immigrants from countries such as Cambodia, Ethiopia, the Philippines, Somalia and Vietnam (Tanner, AP/Los Angeles Times, 7/23). According to the study, U.S. immigrants from sub-Saharan Africa and Southeast Asia account for 22% of the foreign-born population but make up more than half of the TB cases among people born outside the U.S. In addition, TB cases among immigrants to the U.S. increased by 5% from 1993 to 2006, accounting for 57% of all TB cases in the U.S. in 2006, the study found.

The researchers also found high rates of drug-resistant TB among immigrants from China, Peru, the Philippines and Vietnam (Reuters, 7/22). The study found that 20% of recent immigrants from Vietnam and 10% of foreign-born residents living with TB had drug-resistant TB, compared with about 4% of U.S.-born residents living with TB (AP/Los Angeles Times, 7/23).

The study called for improved efforts to screen people from high-risk countries for TB before they depart their home countries or to test them and begin treatment when they arrive in the U.S. (Reuters, 7/22). According to the researchers, a similar screening effort among immigrants and refugees from the Philippines and Vietnam would have detected almost half of the approximately 250 TB cases that were brought into the U.S. annually between 2001 and 2006 (Bloomberg/Long Island Newsday, 7/23).

Under a U.S. law, CDC conducts an overseas screening process to detect active TB cases among people immigrating to the U.S. However, according to Cain, approximately 30% of foreign-born people in the U.S. -- including temporary workers, tourists, students and undocumented immigrants -- do not undergo the screening process (Reuters, 7/22). In addition, although most TB cases develop within the first two years after arriving in the U.S., many latent TB cases do not become contagious until after immigrants have been living in the U.S. for several years. Identifying and treating latent TB would be another step to help curb the spread of the disease, Cain said. Cain added that screening immigrants who feel healthy would require sensitivity to cultural differences (Reuters, 7/22). Cain added that it "would be daunting" to screen the 37 million foreign-born residents for TB.

Henry Blumberg of the Emory University School of Medicine said the research demonstrates that "it's in the interest" of the U.S. to improve efforts to fight TB worldwide (AP/Los Angeles Times, 7/23). The "goal" of U.S. health officials "should be [to] address this serious health concern in the communities that need it most," Cain said, adding that "[a]s long as TB is out of control globally it will be a problem" in the U.S. (Reuters, 6/22).

An abstract of the study is available online.

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