Decrease in reported tuberculosis cases - United States, 2009.

Every year, CDC reports results from the National TB Surveillance System for the previous year. For 2009, a total of 11,540 tuberculosis (TB) cases were reported in the United States. The TB rate was 3.8 cases per 100,000 population, a decrease of 11.4% from the rate of 4.2 per 100,000 reported for 2008. The 2009 rate showed the greatest single-year decrease ever recorded and was the lowest recorded rate since national TB surveillance began in 1953. TB case counts and rates decreased substantially among both foreign-born and U.S.-born persons, although foreign-born persons and racial/ethnic minorities continued to have TB disease disproportionate to their respective populations. The TB rate in foreign-born persons was nearly 11 times higher than in U.S.-born persons. The rates among Hispanics and blacks were approximately eight times higher than among non-Hispanic whites, and rates among Asians were nearly 26 times higher. The large decrease in reported cases during 2009 might represent a decrease in TB disease resulting from changes in population demographics or improved TB control. However, increased underreporting or underdiagnosis of TB also is possible. CDC currently is investigating possible causes for the sharp decrease in reported TB cases. Diagnosing and reporting all TB cases is essential to ensure treatment of patients with TB and implementation of other public health interventions that interrupt transmission.