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Epidemiologic Notes and Reports Expanded Tuberculosis Surveillance and Tuberculosis Morbidity -- United States, 1993

Because of the resurgence of tuberculosis (TB) in the United States, in 1987 the Advisory Committee for the Elimination of Tuberculosis recommended the strengthening of TB surveillance to improve monitoring and to assist in targeting groups at risk for disease (1). In addition, because of outbreaks of nosocomial multidrug-resistant TB (MDR-TB) in New York and Florida during 1990-1992 (2), in 1992, the National MDR TB Task Force recommended that drug-susceptibility testing be performed on all initial and final Mycobacterium tuberculosis isolates from each TB patient and that the results be reported to CDC (3). In January 1993, in conjunction with state and local health departments, CDC implemented an expanded surveillance system for TB. This report summarizes final TB surveillance data for 1993, compares findings with previous years, and provides information on expanded surveillance.

In November 1992, following approval of the Report of a Verified Case of TB (RVCT) form for reporting TB cases to CDC, TB programs in state and local health departments were asked to use the new surveillance form beginning January 1993. In July 1993, a new computer software package (SURVS-TB) was distributed for data entry, analysis, and transfer of records to CDC. Additional elements of the RVCT included results for human immunodeficiency virus (HIV) testing, occupation, history of substance abuse, homelessness, and residence in a correctional or long-term-care facility. To evaluate the outcomes of antituberculous therapy, information was collected about initial therapy, type of health-care provider, sputum culture conversion, and use of directly observed therapy (DOT).

In 1993, 25,313 cases of TB (9.8 cases per 100,000 population) were reported to CDC from the 50 states, the District of Columbia, and New York City (Figure_1), a 5.1% decrease from 1992 (26,673 {10.5 cases per 100,000}) (4) but a 14% increase over 1985 (22,201) (the year with the lowest number of TB cases since national reporting began in 1953). During 1985-1993, there was an excess of approximately 64,000 reported cases, compared with the number predicted based on the trend of decline from 1980 through 1984.

During 1993, 33 states reported fewer TB cases than in 1992; in comparison, during 1992, 27 states and the District of Columbia reported fewer cases than in 1991. The states reporting fewer cases in 1993 included those characterized by the greatest increases in cases since 1985 (California, New York, and Texas). Fifteen states and the District of Columbia reported increases in TB cases (Table_1).

Compared with 1992, the number of reported TB cases decreased for all age groups except for persons aged less than 15 years. Decreases were greatest for persons aged 15-24 (6.6%) and 25-44 years (7.8%). Among persons aged less than 15 years, the number of cases increased 0.8%; of all cases, the proportion accounted for by persons in this group increased from 6.4% in 1992 to 6.8% in 1993. During 1993, persons born outside the United States and its territories (i.e., foreign-born) composed 29.6% of reported cases, compared with 27.4% in 1992.

Selected characteristics were analyzed for cases in states where greater than or equal to 75% of records contained information requested for the first time in 1993 (Table_2). Among these persons, injecting-drug use was reported by 2.4%, noninjecting-drug use by 4.7%, excessive use of alcohol during the preceding 12 months by 13.0%, and homelessness by 5.3%. For patients aged 25-44 years, HIV test results were reported for 33%; 18 reporting areas reported HIV results for greater than or equal to 50% of cases. These 18 reporting areas accounted for 63% of cases in persons aged 25-44 years with HIV results.

From January 1, 1993, through May 25, 1994, antibiotic-susceptibility results for M. tuberculosis isolates were reported for 10,941 (54%) of the 20,090 persons with culture-positive TB. For 26 reporting areas, drug-susceptibility results were available for greater than or equal to 75%; however, these areas included only two of the 12 states in which greater than or equal to 1% of cases had isoniazid and rifampin resistance in the previous national survey (5).

Reported by: Div of Tuberculosis Elimination, National Center for Prevention Svcs, CDC.

Editorial Note

Editorial Note: The findings in this report document a substantial decrease in the number of reported TB cases from 1992 to 1993 (5.1%; p less than 0.001 *), probably reflecting the effectiveness of prevention and control measures implemented during 1989-1993. However, a portion of this decrease may be due to two other factors, including 1) delayed reporting caused by use of the new TB surveillance reporting form and the change from paper records to a computerized system; and 2) underreporting because of modification of the acquired immunodeficiency syndrome (AIDS) surveillance case definition in January 1993 (6).

Following the resurgence of TB in 1985 and the recognition of nosocomial outbreaks of MDR-TB in 1991 (2), the Public Health Service increased funding to state and local health departments for TB-prevention and TB-control activities, including DOT -- which has been shown to reduce TB case rates even in the presence of HIV infection -- and screening programs for persons at high risk for TB infection (7-9). In addition, some hospitals implemented recommendations to prevent nosocomial transmission of M. tuberculosis (10). These measures may account for a substantial proportion of the decrease in reported TB cases in 1993.

Most states require that laboratories notify the health department about patients with cultures positive for M. tuberculosis; during 1993, 79% of all reported TB cases were culture-positive for M. tuberculosis. In response to the initial report, local health departments conduct investigations to verify the diagnosis of TB and to collect information needed for completion of reporting. The addition of information needed for the new TB surveillance form may have delayed investigation of suspected TB cases and completion of case reports in 1993. Ongoing analysis is assessing the impact of delayed reporting.

The expansion of the TB surveillance system during 1993 coincided with the revision of the AIDS surveillance case definition. The revised AIDS case definition classifies as AIDS cases HIV-infection in persons who have either pulmonary TB or extrapulmonary TB (6). As a consequence, HIV-infected persons with pulmonary or extrapulmonary TB may have been reported to the AIDS surveillance program at the local or state health department but not to the TB program. This explanation may account for the apparent decrease in the number of reported TB cases in states characterized by a high incidence of AIDS (California, New York, and Texas) and in persons aged 15-24 and 25-44 years.

In the states with the largest TB/AIDS co-morbidity (i.e., California and New York), laws to protect the confidentiality of persons with AIDS have been interpreted to prohibit the disclosure of patients' names to anyone outside the AIDS program, including other programs within the state health department. Information on the HIV status of persons with TB in 1993 is incomplete (missing/unknown for 67% of TB patients in the 25-44-year age group); thus, the impact of HIV on the TB epidemic in the United States can only be indirectly measured in 1993. Collaboration between TB and HIV/AIDS surveillance programs will be necessary to accurately measure the extent of overlap between the TB and HIV epidemics.

Maintaining the current decline in TB morbidity and reaching the goal of eliminating TB in the United States will require sustaining prevention and control activities. In particular, health-care providers should attempt to identify all TB cases and report them to health departments and ensure that persons with active TB successfully complete treatment (e.g., DOT). In addition, TB skin-test screening programs that target persons at highest risk (e.g., contacts of persons with active cases) can ensure appropriate use of preventive therapy.


  1. CDC. A strategic plan for the elimination of tuberculosis in the United States. MMWR 1989;38(no. S-3).

  2. CDC. Nosocomial transmission of multidrug-resistant tuberculosis among HIV-infected persons -- Florida and New York, 1988-1991. MMWR 1991;40:585-91.

  3. CDC. National action plan to combat multidrug-resistant tuberculosis. MMWR 1992;41 (no. RR-11):1-48.

  4. CDC. Tuberculosis morbidity -- United States, 1992. MMWR 1993;42:696-7,703-4.

  5. Bloch AB, Cauthen GM, Onorato IM, et al. Nationwide survey of drug-resistant tuberculosis in the United States. JAMA 1994;271:665-71.

  6. CDC. 1993 Revised classification system for HIV infection and expanded surveillance case definition for AIDS among adolescents and adults. MMWR 1992;41(no. RR-17).

  7. Weis SE, Slocum PC, Blais FX, et al. The effect of directly observed therapy on the rates of drug resistance and relapse in tuberculosis. N Engl J Med 1994;330:1179-84.

  8. Chaulk CP, Chaisson RE, Lewis JN, Rizzo RT. Treating multidrug-resistant tuberculosis: compliance and side effects {Letter}. JAMA 1994;271:103-4.

  9. CDC. Tuberculosis prevention in drug-treatment centers and correctional facilities -- selected U.S. sites, 1990-1991. MMWR 1993;42:210-3.

  10. Fridkin SK, Manangan LP, Mayhall CG, et al. A survey of the use and efficacy of tuberculosis infection precautions. Proceedings of the Fourth Annual Meeting of the Society for Hospital Epidemiology of America. West Deptford, New Jersey: Society for Hospital Epidemiology of America, March 1994.

* Statistical significance assessed by Chi Square test for dispersion; statistical tests for differences in surveillance data must be interpreted in relation to epidemiologic and programmatic considerations.

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TABLE 1. Reported tuberculosis cases, by reporting area -- United States, 1992-1993
                          No. reported cases
Reporting area              1992       1993     % Change
Areas with decreases
  Arizona                    259        231      -10.8
  Arkansas                   257        209      -18.7
  California                5382       5212      - 3.2
  Colorado                   104        102      - 1.9
  Connecticut                156        155      - 0.6
  Florida                   1707       1655      - 3.0
  Georgia                    893        810      - 9.3
  Hawaii                     273        251      - 8.1
  Idaho                       26         12      -53.8
  Illinois                  1270       1242      - 2.2
  Louisiana                  373        367      - 1.6
  Maryland                   442        406      - 8.1
  Massachusetts              428        370      -13.6
  Michigan                   495        480      - 3.0
  Minnesota                  165        141      -14.5
  Mississippi                281        279      - 0.7
  Nebraska                    28         22      -21.4
  Nevada                      99         98      - 1.0
  New Jersey                 984        912      - 7.3
  New Mexico                  88         74      -15.9
  New York                  4574       3953      -13.6
  North Carolina             604        594      - 1.7
  North Dakota                11          7      -36.4
  Ohio                       358        315      -12.0
  Oklahoma                   216        209      - 3.2
  Pennsylvania               758        746      - 1.6
  South Dakota                32         16      -50.0
  Texas                     2510       2396      - 4.5
  Utah                        78         46      -41.0
  Washington                 306        286      - 6.5
  West Virginia               92         75      -18.5
  Wisconsin                  106        100      - 5.7
  Wyoming                      8          7      -12.5

Areas with increases
  Alabama                    418        487      +16.5
  Delaware                    55         66      +20.0
  District of Columbia       146        161      +10.3
  Indiana                    247        248      + 0.4
  Iowa                        49         59      +20.4
  Kansas                      56         80      +42.9
  Kentucky                   402        405      + 0.7
  Maine                       24         27      +12.5
  Missouri                   245        257      + 4.9
  Montana                     16         22      +37.5
  New Hampshire               18         26      +44.4
  Oregon                     145        154      + 6.2
  Rhode Island                54         64      +18.5
  South Carolina             387        401      + 3.6
  Tennessee                  527        556      + 5.5
  Virginia                   457        458      + 0.2

Areas with no change
  Alaska                      57         57        0
  Vermont                      7          7        0

Total                     26,673     25,313       -5.1

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TABLE 2. Reported tuberculosis cases, by selected characteristic, number of cases with information about
>=75% of cases, and percentage of cases with characteristics -- United States *, 1993
                         No. areas with information         % Cases
Characteristic                for >=75% of cases        with characteristic +
Initial drug regimen                 50                         ---
  Isoniazid and rifampin             ---                       14.2
  Isoniazid, rifampin,
    and pyrazinamide                 ---                       39.9
  Isoniazid, rifampin,
    and ethambutol
    or streptomycin                  ---                       32.5
  Other                              ---                       13.4

Injecting-drug use                   15                         2.4

Noninjecting-drug use                15                         4.7

Excessive alcohol use &              11                        13.0

Homelessness                         36                         5.3

  Correctional institution           47                         3.7
  Long-term-care facility            45                         4.5

Occupation                           23                         ---
  Health-care worker                 ---                        3.2
  Correctional employee              ---                        0.2
  Migrant worker                     ---                        0.8
  Unemployed                         ---                       68.2
  Other                              ---                       27.6
* Comprises the 50 states, the District of Columbia, and New York City.
+ Comprises reporting areas with information on characteristics reported for >=75% of cases.
& During preceding 12 months.

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