Trends in Tuberculosis — United States, 2011

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In 2011, a total of 10,521 new tuberculosis (TB) cases were reported in the United States, an incidence of 3.4 cases per 100,000 population, which is 6.4% lower than the rate in 2010. This is the lowest rate recorded since national reporting began in 1953 (1). The percentage decline is greater than the average 3.8% decline per year observed from 2000 to 2008 but not as large as the record decline of 11.4% from 2008 to 2009 (2). This report summarizes 2011 TB surveillance data reported to CDC's National Tuberculosis Surveillance System. Although TB cases and rates decreased among foreign-born and U.S.-born persons, foreign-born persons and racial/ethnic minorities continue to be affected disproportionately. The rate of incident TB cases (representing new infection and reactivation of latent infection) among foreign-born persons in the United States was 12 times greater than among U.S.-born persons. For the first time since the current reporting system began in 1993, non-Hispanic Asians surpassed persons of Hispanic ethnicity as the largest racial/ethnic group among TB patients in 2011. Compared with non-Hispanic whites, the TB rate among non-Hispanic Asians was 25 times greater, and rates among non-Hispanic blacks and Hispanics were eight and seven times greater, respectively. Among U.S.-born racial and ethnic groups, the greatest racial disparity in TB rates occurred among non-Hispanic blacks, whose rate was six times the rate for non-Hispanic whites. The need for continued awareness and surveillance of TB persists despite the continued decline in U.S. TB cases and rates. Initiatives to improve awareness, testing, and treatment of latent infection and TB disease in minorities and foreign-born populations might facilitate progress toward the elimination of TB in the United States.

Health departments in the 50 states and the District of Columbia electronically report to CDC verified TB cases that meet the CDC and Council of State and Territorial Epidemiologists surveillance case definition.* Reports include the patient's self-identified race, ethnicity (i.e., Hispanic or non-Hispanic), human immunodeficiency virus (HIV) status, treatment information, and drug-susceptibility test results. CDC calculates national and state TB rates overall and by racial/ethnic group, using U.S. Census Bureau population estimates (3). As of March 22, 2012, race/ethnicity intercensal population estimates were unavailable for 2011; therefore, 2010 population estimates were used as denominators to calculate 2011 case rates. The Current Population Survey provides the population denominators used to calculate TB rates and percentage changes according to national origin.† Because 2011 Current Population Survey data were available, 2011 population estimates were used for U.S.-born and foreign-born TB rates. For TB surveillance, a U.S.-born person is defined as someone born in the United States or its associated jurisdictions, or someone born in a foreign country but having at least one U.S.-citizen parent. In 2011, 0.4% of patients had unknown country of birth, and 0.7% had unknown race or ethnicity. For this report, persons of Hispanic ethnicity might be of any race; non-Hispanic persons are categorized as black, Asian, white, American Indian or Alaska Native, Native Hawaiian or other Pacific Islander, or of multiple races.

Compared with the national TB case rate of 3.4 cases per 100,000 population, TB rates in reporting areas ranged widely, from 0.7 in Maine to 9.3 in Alaska (median: 2.4) (Figure 1). Thirty-four states had lower rates in 2011 than in 2010; 16 states and the District of Columbia had higher rates. As in 2010, four states (California, Florida, New York, and Texas) continued to report more than 500 cases each in 2011. Combined, these four states accounted for 5,299 TB cases or approximately half (50.4%) of all TB cases reported in 2011.

Among U.S.-born persons, the number and rate of TB cases declined in 2011. The 3,929 TB cases in U.S.-born persons (37.5% of all cases in persons with known national origin) represented a 9.9% decrease compared with 2010 and a 77.5% decrease compared with 1993 (Figure 2). The rate of 1.5 TB cases per 100,000 population among U.S.-born persons represented a 10.3% decrease since 2010 and an 80.1% decrease since 1993.

The difference between the proportion of U.S.-born and foreign-born persons with TB continued to increase, although the number and rate of TB cases among foreign-born persons in the United States declined in 2011. A total of 6,546 TB cases were reported among foreign-born persons (62.5% of all cases in persons with known national origin), a 3.0% decrease from 2010. The 17.3 per 100,000 population TB rate among foreign-born persons was a 4.8% decrease since 2010 and a 49.0% decrease since 1993. In 2011, 54.1% of foreign-born persons with TB originated from five countries: Mexico (n = 1,392 [21.3%]), the Philippines (n = 750 [11.5%]), Vietnam (n = 537 [8.2%]), India (n = 498 [7.6%]), and China (n = 365 [5.6%]).

During the past 12 years, the proportion of TB cases occurring in Asians has increased steadily, from 20.5% in 2000 to 29.9% in 2011. More TB cases were reported among Asians than any other racial/ethnic group in the United States in 2011 (Table). From 2010 to 2011, TB rates decreased most for blacks, then Hispanics, whites, and Asians. Among persons with TB, 95.4% of Asians, 73.9% of Hispanics, 36.4% of blacks, and 20.9% of whites were foreign-born. Among U.S.-born persons, blacks were the racial/ethnic group with the greatest percentage of TB cases (38.6%) and the largest disparity compared with U.S.-born whites.

HIV test result reporting improved in 2011, with 81% of cases reported having a known HIV status. Among persons with TB who had a known HIV test result, 7.9% were coinfected with HIV. Vermont data were not available.§

A total of 109 cases of multidrug-resistant TB (MDR TB)¶ were reported in 2010, the most recent year for which complete drug-susceptibility data were available. Drug-susceptibility test results for isoniazid and rifampin were reported for 97.5% and 97.1% of culture-confirmed TB cases in 2009 and 2010, respectively. Among these cases, the percentage of MDR TB for 2010 (1.3% [109 of 8,422]) was unchanged from the percentage for 2009 (1.3%). The percentage of MDR TB cases among persons without a previous history of TB has remained stable at approximately 1.0% since 1997. For persons with a previous history of TB, the percentage with MDR TB in 2010 was approximately four times greater than among persons not previously treated for TB. In 2010, foreign-born persons accounted for 90 (82.6%) of the 109 MDR TB cases. Four cases of extensively drug-resistant TB** (all occurring in foreign-born persons) have been reported for 2011.

Reported by

Roque Miramontes, MPH, Robert Pratt, Sandy F. Price, Carla Jeffries, MPH, Thomas R. Navin, MD, Div of TB Elimination, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention; Gloria E. Oramasionwu, MD, EIS Officer, CDC. Corresponding contributor: Gloria E. Oramasionwu, iyo8@cdc.gov, 404-718-8633.

Editorial Note

Despite the continued decline in U.S. TB cases and rates since 1993, the 6.4% decline from 2010 to 2011 to a rate of 3.4 per 100,000 falls short of the 2010 goal of TB elimination (less than one case per 1,000,000) set in 1989 (4). If current efforts are not improved or expanded, TB elimination is unlikely before the year 2100 (5).

In 2011, Asians became the largest single racial/ethnic group represented among TB cases, with a case rate 25 times that of non-Hispanic whites. Although the case rate among Asians declined in 2011 compared with 2010, this 0.6% decline was smaller than among any other racial/ethnic group. This finding underscores the need for increased TB awareness and prevention programs in Asian communities. A decrease in TB rates was associated with one such program, implemented in predominantly black and Hispanic neighborhoods in Texas, which raised TB awareness in the community while also treating anyone found to have latent TB infection (LTBI) (6). Moreover, because 95% of Asians with TB in 2011 were foreign-born, further support of global TB control will be important for reducing TB rates.

Addressing the increasing difference between TB rates in foreign-born and U.S.-born persons is critical for TB elimination. Most foreign-born persons with TB (78.8%) had their TB diagnosed after being in the United States for more than 2 years,†† consistent with reactivation of LTBI acquired abroad. Therefore, treating LTBI will be critical for accelerating the TB decline among foreign-born persons (5). In 2007, CDC published technical instructions for TB screening in prospective immigrants to the United States (7). As more high-TB burden countries adopt these technical instructions, screening and treating immigrants should improve. Persons screened overseas and found to have LTBI should receive preventive TB treatment upon arrival in the United States. A new, shorter regimen for LTBI requiring just 12 once-weekly drug administrations has been recommended by CDC and might result in better adherence to LTBI treatment in foreign-born and U.S.-born populations (8,9).

Approximately 81% of TB cases in 2011 had known HIV status at TB diagnosis. This increase (66.3% in 2010) is attributed to increased reporting from selected regions. The American Thoracic Society and the Infectious Disease Society of America recommend that all TB patients be counseled and tested for HIV (10).

This analysis is limited to reporting provisional TB cases and case rates for 2011. Case rates are based on estimates of population denominators from either 2010 or 2011. CDC's annual TB surveillance report will provide final TB case rates based on updated denominators later this year.

Progress toward TB elimination in the United States will require ongoing surveillance and improved TB control and prevention activities. Sustained focus on domestic TB control activities and further support of global TB control initiatives is important to address persistent disparities between non-Hispanic whites and racial/ethnic minorities and between U.S.-born and foreign-born persons.

Acknowledgments

State and local TB control officials.

References

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