TB eradication in the U.S. by 2010 unlikely: survey

NEW YORK (Reuters Health) - The U.S. is unlikely to meet its goal for eliminating tuberculosis (TB) by 2010, primarily because of high rates of latent (dormant) TB infection in certain population subgroups, according to a nationwide survey.

According to the new survey, latent TB infection prevalence in the 1999-2000 U.S. population -- excluding homeless and incarcerated individuals -- was 4.2 percent. The current infection rate would have to be 1 percent and decreasing if the U.S. were on course to reach its goal of TB incidence of less than one per million by 2010.

Dr. Thomas R. Navin, of the Centers for Disease Control and Prevention in Atlanta, Georgia, and colleagues report their findings in the February 1 issue of the American Journal of Respiratory and Critical Care Medicine.

Persons with latent TB are not infectious, they do not feel sick, and cannot transmit TB to others. About 10 percent of individuals with latent TB will go on to develop active TB, which is infectious. The risk of progression to active TB can be markedly reduced by preventive treatment, making it important to detect and treat latent TB, experts say.

To estimate the prevalence of latent TB infection in the U.S., Navin and colleagues evaluated data from the National Health and Nutrition Examination Survey (NHANES) 1999-2000 TB component, the first survey to examine TB prevalence since 1971-1972.

TB tests were obtained in 7386 individuals and the prevalence of TB was 4.2 percent, as mentioned. Only 25.5 percent of those with latent TB had been previously diagnosed, Navin and his team report, and only 13.2 percent had been treated for TB.

Latent TB infection was diagnosed at a much higher frequency in immigrants (18.7 percent) than in U.S.-born individuals (1.8 percent). Latent TB was also much more common in people living below the poverty level (6.1 percent) than in those living above the poverty level (3.3 percent).

Higher latent TB infection rates were also seen among non-Hispanic blacks and Mexican Americans compared with non-Hispanic whites.

Continuing basic TB control measures, as well as targeted evaluation and appropriate treatment of individuals in high-prevalence groups -- including immigrants, racial and ethnic minorities, and poor people -- "are needed to further TB elimination efforts in the United States," Navin and colleagues maintain.

Moreover, they suggest, "support for global TB prevention and control efforts in high-burden countries is ... not only a matter of humanitarian concern, but a matter of enlightened self-interest."

SOURCE: American Journal of Respiratory and Critical Care Medicine, February 1, 2008.