Eliminating tuberculosis in the United States

Jan 2 2007

To eliminate tuberculosis (TB) in the United States, current guidelines should be changed to reclassify all foreign-born residents from high-incidence countries as "high-risk," regardless of the amount of time they have lived in the U.S.

These findings appear in the first issue for January 2007 of the American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society.

Kevin P. Cain, M.D., of the Division of Tuberculosis Elimination at the Centers for Disease Control and Prevention in Atlanta, and seven associates collected data on all 2004 TB cases listed in the U.S. National TB Surveillance database. The investigators' aim was to understand why the number of annual cases of TB reported in U.S.-born persons declined by 93 percent from 1993 to 2004, while foreign-born cases increased by five-percent.

"For example, in 2004, a total of 14,517 cases of TB were reported," said Dr. Cain. "Of these, 3,444 or 24 percent were foreign-born persons who had entered the United States more than five years previously."

Present guidelines recommend only those residing in the U.S. for five years or less be targeted for tuberculin skin testing and treatment of latent TB infection.

The following countries of origin of U.S. immigrant residents had the largest number of TB cases in 2004: Mexico (1,976), Philippines (829), Vietnam (619), India (557), China (352), Haiti (248), South Korea (219), Guatemala (190), Ethiopia (169) and Peru (159).

"Twenty-five percent of all reported TB cases in the United States are among foreign-born persons who have lived in the U.S. for more than five years," said Dr. Cain. "There is no policy to test foreign-born persons for latent TB infection before entering the U.S., or to test them after they have lived here for more than five years. As such, present guidelines do not currently address the burden of latent TB infection in the foreign-born subgroup."

According to the authors, the goal of TB control efforts in the U.S. is eliminating the disease. They define elimination as less than one case reported per million in a given population. If achieved, the number of TB cases diagnosed in 2004 would have been less than 300, as contrasted to the 14,517 reported.

"Until we address the burden of latent TB infection in the foreign-born group, achieving TB elimination will not be possible," said Dr. Cain.

He noted that controlling and eliminating TB will require a comprehensive strategy, with varying approaches for immigrant populations from high-risk countries.