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Latent Tuberculosis Infection (LTBI): Whom to Treat



Highest Priority (Regardless of Age)

All household or other close contacts of persons with current pulmonary tuberculosis

  • High-risk contacts including children under 5 years and immunocompromised individuals (HIV infection, chronic corticosteroids,
    chemotherapy, etc) should receive treatment for LTBI regardless of tuberculin skin test (TST) reaction if the index case is
    smear or culture (+) for M. tuberculosis.
  • Refer to Contact Investigation Guidelines for other groups
  • At 8-10 weeks following exposure, contacts with a negative IGRA or TST (<5mm) will be retested. If the non-
    immunocompromised contact is still negative (includes children) and the index case is on TB chemotherapy, treatment of LTBI
    may be discontinued. Immunocompromised close contacts should complete a full course of treatment regardless of repeat TST
    results since test results may be unreliable.


TB Test Converters

  • TST Converter: Increase in the size of the tuberculin reaction by at least 10 mm from less than 10 mm to 10 mm or more within
    a 2 year period.
  • IGRA Converter, Contact: Current positive test with a documented prior negative result within the past two years
  • IGRA Converter, non-Contact: Current positive test with a documented prior negative result within the past two years


IGRA positive or TST reactors (5mm or greater)with abnormal chest films 

Consistent with dormant tuberculosis patients that have not had adequate prior therapy. It is important to exclude current disease by bacteriologic evaluation and/or a review of serial x-rays.


IGRA positive or TST reactors (5mm or greater) with HIV infection or at high risk of HIV infection.


IGRA positive or TST reactors (10mm or greater) who are injection drug users

(HIV testing should be strongly encouraged for all individuals in this group) and have a risk factor for progression as listed in special medical conditions. 


IGRA positive or TST reactors (10mm or greater) who are homeless

or have a transient living arrangement and is a TST converter, contact, or is HIV infected or immunosuppressed 

  • Because of increased TB disease susceptibility and probability of TB exposure in group settings, HIV testing should be strongly
    encouraged for all homeless tuberculin reactors). 
  • These patients should always be placed on DOT


IGRA positive or TST reactors with special medical conditions

that increase risk of disease progression. Prioritization of contacts, foreign-born and homeless persons with the following conditions should be made:

  • HIV infection
  • Diabetes mellitus
  • Current tobacco smokers 
  • Immunosuppressive therapy such as prolonged corticosteriod therapy (>15mg daily of prednisone or equivalent for 2-4 weeks),
    TNF-antagonists, post-transplant immunosuppressive drugs, and cancer chemotherapy. 
  • Cancer of the head and neck and hematologic malignancies (leukemia or lymphoma
  • End-stage renal disease
  • Organ transplant candidates/recipients
  • Intestinal bypass or gastrectomy (especially with weight loss)
  • Low body weight (10% or more below ideal)
  • Silicosis

Note: a 5 mm TST cut point is considered positive for persons who are on immunosuppressive therapy, corticosteroids, or have leukemia or lymphoma.  A 10mm cut point should be used for other medical risk groups. 


Less than 50 years of age foreign-born IGRA positive or TST reactors (10 mm or greater

 who come from areas of the world with a high TB incidence (includes Central and South America, Asia, Philippines, the former Soviet Union, and Africa)

For additional information about LTBI treatment regimens, completion and monitoring see:

San Francisco Treatment Guidelines for Latent Tuberculosis Infection


Nursing/Pharmacy Monitoring of LTBI Treatment in the Community-Oriented Primary Care Clinics 


Sample Treatment Refill No-show Letter 


Sample Script to Explain LTBI Treatment 



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