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U.S. Department of Health and Human Services


Core Curriculum on Tuberculosis, 2000

Chapter 6
Treatment of Latent TB Infection (LTBI)

Candidates for Treatment of Latent TB Infection

Targeted testing programs should be designed to identify persons who are at high risk for TB and who would benefit from treatment of LTBI. Careful assessment to rule out the possibility of TB disease is necessary before treatment for LTBI is started.

Persons in the following high-risk groups should be given treatment for LTBI if they have positive skin test results (>= 5 mm):

  • HIV-positive persons;
  • Recent contacts of a TB case;
  • Persons with fibrotic changes on chest radiograph consistent with old TB;
  • Patients with organ transplants, and other immunosuppressed patients (receiving the equivalent of >= 15mg/day of prednisone for >= 1 month).

In addition, persons in the following high-risk groups should be considered for treatment of LTBI if their reaction to the tuberculin skin test is >= 10mm:

  • Recent arrivals (< 5 years) from high-prevalence countries;
  • Injection drug users;
  • Residents and employees of high-risk congregate settings (e.g., correctional facilities, nursing homes, homeless shelters, hospitals, and other health care facilities);
  • Mycobacteriology laboratory personnel;
  • Persons with clinical conditions that make them high-risk (see Transmission and Pathogenesis);
  • Children < 4 years of age, or children and adolescents exposed to adults in high-risk categories.

No Known Risk Factors
Persons with no known risk factors for TB may be considered for treatment of LTBI if their reaction to the tuberculin test is >=15 mm. This group should be given a lower priority for prevention efforts than the groups listed above.

Close Contacts
Some contacts who have a negative tuberculin skin test reaction (less than 5 mm of induration) should be evaluated for treatment of LTBI, after TB disease has been ruled out. These contacts include children under 4 years of age, immunosuppressed people, and others who may develop TB disease quickly after infection. Close contacts who have a negative reaction to an initial skin test should be retested 10 to 12 weeks after they were last exposed to TB. Treatment of latent infection may be discontinued if the skin test result is again negative and if the person is no longer exposed to TB. However, persons known to have or suspected of having HIV infection and other immunocompromised persons should be given treatment for LTBI regardless of their skin test reaction.

Children and Adolescents
Because or their age, infants and young children with LTBI are known to have been infected recently, and thus are at a high risk of their infection progressing to disease. Infants and young children are also more likely than older children and adults to develop life-threatening forms of TB. Children < 4 years of age who are close contacts should receive treatment for LTBI even if the tuberculin skin test result and chest radiograph do not suggest TB, because infected infants may be anergic as late as 6 months of age. A second tuberculin test should be placed 10-12 weeks after the last exposure to infectious TB. Treatment of LTBI can be discontinued if all of the following conditions are met:

  • The infant is at least 6 months of age;
  • The second tuberculin test is also negative;
  • The second test was performed at least 10 weeks after the child was last exposed to infectious TB.


Released October 2008
Centers for Disease Control and Prevention
National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention
Division of Tuberculosis Elimination -

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