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U.S. Department of Health and Human Services

  

Core Curriculum on Tuberculosis, 2000

Chapter 4
Testing for TB Disease and Infection

Groups That Should Be Tested

In most U.S. populations, targeted testing for TB is done to find persons with infection and disease who would benefit from treatment. Therefore, all testing activities should be accompanied by a plan for follow-up care of persons with LTBI or disease. Healthcare agencies or other facilities should consult with the local health department before starting a skin-testing program to ensure that adequate provisions are made for the evaluation and treatment of persons whose tuberculin skin tests results are positive. Testing for TB infection should be done in well-defined groups. These high-risk groups can be divided into two categories:

  • Persons at higher risk for TB exposure or infection
  • Persons at higher risk for TB disease once infected

Groups that are not at high risk for TB should not be tested routinely, because testing in low-risk populations diverts resources from other priority activities and because positive tests in low-risk persons may not represent TB infection. Flexibility is needed in defining high-priority groups for testing. The changing epidemiology of TB indicates that the risk for TB among groups currently considered high priority may decrease over time, and groups currently not identified as being at risk subsequently may be considered as high priority.

In general, high-risk groups that should be tested for infection include:

Persons at higher risk for TB exposure or infection

  • Close contacts of persons known or suspected to have TB (i.e., those sharing the same household or other enclosed environments)
  • Foreign-born persons, including children, from areas that have a high TB incidence or prevalence (e.g., Asia, Africa, Latin America, Eastern Europe, Russia)
  • Residents and employees of high-risk congregate settings (e.g., correctional institutions, nursing homes, mental institutions, other long-term residential facilities, and shelters for the homeless)
  • Health care workers who serve high-risk clients
  • Some medically underserved, low-income populations as defined locally
  • High-risk racial or ethnic minority populations, defined locally as having an increased prevalence of TB (e.g., Asians and Pacific Islanders, Hispanics, African Americans, Native Americans, migrant farm workers, or homeless persons)
  • Infants, children, and adolescents exposed to adults in high-risk categories
  • Persons who inject illicit drugs; any other locally identified high-risk substance users (e.g., crack cocaine users)

Persons at higher risk for TB disease once infected

  • Persons with HIV infection
  • Persons who were recently infected with M. tuberculosis (within the past 2 years), particularly infants and very young children
  • Persons who have medical conditions known to increase the risk for disease if infection occurs, e.g., diabetes, end stage renal disease (see Transmission and Pathogenesis)
  • Persons who inject illicit drugs; other groups of high-risk substance users (e.g., crack cocaine users)
  • Persons with a history of inadequately treated TB

The preferred method of testing for TB infection in adults and children is the Mantoux tuberculin skin test. In some circumstances, testing for TB disease with chest radiographs or sputum smears may be more appropriate than testing for infection with the tuberculin skin test. For example, chest radiography is the preferred screening method when the objective is to identify persons who have current pulmonary TB and when treatment for LTBI is not the primary goal (e.g., in high-turnover jails or in some homeless shelters). Testing for TB infection or disease should always be carried out in consultation with the health department. Facilities such as drug treatment programs or long-term care facilities should test high-risk groups only when appropriate follow-up measures can be provided, either by that facility or by the health department.

Clinicians should identify patients who are in a high-risk category (high risk for acquiring infection or high risk of progressing to disease once infected), and they should give tuberculin skin tests to these persons as part of their routine evaluation. In particular, persons with certain medical conditions known to increase the risk for TB disease (see Transmission and Pathogenesis) should be tuberculin skin tested, and their tuberculin skin test status should be clearly noted on their medical record. Pregnant women should be targeted for tuberculin skin testing only if they have a specific risk factor for LTBI or for progression of LTBI to disease. Persons with a positive reaction should be evaluated for TB disease and, if disease is ruled out, considered for treatment for LTBI. For persons who have a positive PPD and who have had TB disease ruled out, routine follow-up skin tests and chest radiographs are unnecessary. These patients should be instructed to seek medical attention if they experience signs and symptoms suggestive of active TB disease.

Health care workers in facilities or communities where TB cases have occurred should be included in a TB testing and prevention program (see Infection Control in Health Care Facilities). In addition, testing is recommended for the staff of congregate living facilities who 1) may be exposed to persons with TB on the job (e.g., staff of correctional facilities) or 2) would pose a risk to large numbers of susceptible persons if they developed infectious TB (e.g., staff of AIDS hospices). Such persons should be tuberculin skin tested upon employment and thereafter at intervals determined by the risk of transmission in that facility. This testing is done for two reasons:

  • To detect TB infection or disease in staff so that they may be given treatment
  • To determine whether TB is being transmitted in the facility (indicated by skin test conversions among staff)

Health care workers who have a documented history of a positive tuberculin skin test, adequate treatment for disease, or adequate treatment for latent infection, should be exempt from further tuberculin skin testing. Health care workers with positive tuberculin skin test results should have a chest radiograph as part of the initial evaluation of their tuberculin skin test; if negative, repeat chest radiographs are not needed unless symptoms develop that could be attributed to TB. If health care workers with a documented history of a positive tuberculin skin test develop signs and symptoms suggestive of TB, they should undergo a medical evaluation including a chest radiograph. However, more frequent monitoring for symptoms of TB may be considered for recent converters and other tuberculin skin test-positive health care workers who are at increased risk for developing active TB (e.g., HIV-positive or otherwise severely immunocompromised health care workers).

 


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

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