Although it is not feasible to screen all foreign-born entrants to the United States for latent tuberculosis infection, it would be worthwhile to target those at highest risk: those who have immigrated in the past 2 years and those who are from sub-Saharan Africa and Southeast Asia, reported Dr.

Older immigrants also should be screened for latent TB, because the disease prevalence in foreign-born people rises with increasing age, they noted.

Nearly 60% of all TB cases reported in 2006 occurred in the 37 million immigrants now living here, and most of these represent activation of latent TB.

The researchers analyzed data from the national TB surveillance system from 2001 through 2006 to determine which subgroups of immigrants are at highest risk. There were 46,998 TB cases in immigrants during that period.

People born in countries in sub-Saharan Africa and Southeast Asia had more than 250 cases per 100,000 persons per year. Those from Central America, Eastern Europe, the Pacific Islands, and Central Asia had more than 100 cases per 100,000 per year. In total, 53% of TB cases in foreign-born persons occurred in the 22% of the foreign-born population born in sub-Saharan Africa and Southeast Asia.

Prevalence generally decreases after immigrants have lived in the United States for 2 years, but it remains markedly higher than that in native-born persons, the authors wrote (JAMA 2008;300:405-12).