CDC Logo Tuberculosis Information CD-ROM   Image of people
     
jump over main navigation bar to content area
Home
TB Guidelines
Surveillance Reports
Slide Sets
TB-Related MMWRs and Reports
Education/Training Materials
Newsletters
Ordering Information
Help

 

U.S. Department of Health and Human Services

  

Core Curriculum on Tuberculosis, 2000

Chapter 3
Epidemiology of TB in the United States

Trends

After the introduction of anti-TB medication in the late 1940s, there was hope that TB would soon be eradicated. There was a steady decrease in the incidence of TB in the United States from 1953 through 1984 (Figure 1). The number of reported cases declined by an average of 5.6% per year, from more than 84,000 cases in 1953 to 22,255 cases in 1984. 1 However, after decades of steady decline in TB, from 1985 through 1992 the number of reported TB cases increased by 20%. 2 The major factors contributing to this increase were

  • A deterioration of the TB public health infrastructure
  • The HIV/AIDS epidemic
  • Immigration from countries where TB is common
  • Transmission of TB in congregate settings (e.g., health care facilities, correctional facilities, homeless shelters)

Since 1993, the number of reported TB cases has again declined; the nation has recovered from the resurgence of TB that occurred in the mid-1980s, and is back on track toward TB elimination. This decline has been primarily attributed to increased efforts to strengthen TB control programs that promptly identify persons with TB, initiate appropriate treatment, and ensure the completion of therapy. 3

During 1998, a total of 18,361 cases (rate of 6.8 per 100,000 population) of TB were reported to CDC from the 50 states and the District of Columbia, representing an 8% decrease from 1997. 1 This sixth annual consecutive decline in the number of reported TB cases also marks the lowest number and rate of reported TB cases since national reporting began in 1953.

Although the overall number of TB cases is decreasing, TB cases continue to be reported in every state. In 1998 seven states (California, Florida, Georgia, Illinois, New Jersey, New York, and Texas) reported 60% of all TB cases. 1 Cases of TB remain concentrated in urban areas: in 1998, nearly 40% of TB cases were reported from 64 major cities. 1

During 19921998, the overall decrease in TB cases reflected the substantial decline in cases among U.S.-born persons in all age groups and a small increase in the number of cases among foreign-born persons. Although the number of TB cases among foreign-born persons increased 4% during this period, 1 most of these foreign-born TB patients were probably infected before arrival in the United States.  4 The proportion of TB cases among foreign-born persons has increased steadily since the mid-1980s and increased markedly since 1992 (from 27% in 1992 to 42% in 1998) (Figure 2). 1 The TB case rate for foreign-born persons has remained at least four to six times higher than that for U.S.-born persons. 1

Surveillance data have shown that TB in the United States affects racial/ethnic minorities disproportionately. Compared with non-Hispanic whites, Asians are almost 16 times more likely to have TB; African Americans 8 times more likely; and Hispanics, Native Americans, and Alaskan Natives 5 times more likely. 1 However, it has been suggested that much of the increased risk for TB, particularly among U.S.-born persons in these racial/ethnic minorities, may be due to socioeconomic status. 5

HIV-positive persons are at high risk for active TB disease after infection with M. tuberculosis. Because incomplete reporting has limited the analysis of national TB surveillance data by HIV status, state health departments have compared TB and AIDS registries to help estimate the proportion of reported TB cases with HIV coinfection. In the most recent registry comparison conducted by the 50 states and Puerto Rico, 14% of all TB cases reported during 19931994 had a match in the AIDS registry; 27% of cases were in persons aged 2544 years. 6 Both this study and recent TB surveillance data indicate that the impact of the HIV/AIDS epidemic also differs by geographic location. 1

Multidrug-resistant TB (MDR TB), particularly among HIV-positive persons, contributed to the resurgence of TB in the late 1980s and early 1990s. Even now, resistance to anti-TB drugs among reported TB cases in the United States remains a serious public health concern. Since CDC began monitoring anti-TB drug resistance through the national TB surveillance system in 1993, levels of isoniazid resistance have been relatively stable. 1,7 Even among patients without a history of prior TB, resistance to isoniazid was 4% or higher in 46 states and the District of Columbia during 1993-1998. 8 Overall, the number and proportion of MDR TB cases has decreased. 1,7 Nevertheless, 45 states and the District of Columbia reported at least one MDR TB case during 1993-1998 8 (Figure 3). The extent of drug resistance confirms the importance of initial treatment regimens of four first-line drugs for most TB patients and the use of drug susceptibility testing to guide optimal treatment of patients with culture-positive disease. All health departments must be prepared to deal with the challenge of MDR TB, which includes the capacity to ensure that clinicians with expertise in the management of MDR TB are always involved in the care of these patients.

 


Released October 2008
Centers for Disease Control and Prevention
National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention
Division of Tuberculosis Elimination - http://www.cdc.gov/tb

Please send comments/suggestions/requests to: hsttbwebteam@cdc.gov, or to
CDC/Division of Tuberculosis Elimination
Communications, Education, and Behavioral Studies Branch
1600 Clifton Rd., NE - Mailstop E-10, Atlanta, GA 30333