Agent Scully reports

Interferon Gamma Release Assays for Detection of Latent Tuberculosis Infection

AHC Newsletters - Apr. 01, 2009

Interferon Gamma Release Assays for Detection of Latent Tuberculosis Infection

Abstract & Commentary

By Mary Louise Scully MD

Dr. Scully is Director, Travel and Tropical Medicine Center, Sansum Clinic, Santa Barbara, CA.

Dr. Scully reports no financial relationships relevant to this field of study.

Synopsis: Interferon gamma assays now are commercially available for the diagnosis of latent tuberculosis infection and have an advantage over tuberculin skin tests in being better able to identify persons with true latent tuberculosis infections versus prior Bacille Calmette-Guéron (BCG) vaccination.

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The full spectrum of the usefulness of IGRAs will require longitudinal studies and further studies in select populations such as young children and immunosuppressed patients. However, the data are encouraging and support the use of IGRAs in patients previously immunized with BCG. In this scenario, a BCG-vaccinated patient with a positive TST (but no recent high-risk TB exposure) and a negative IGRA test would not require a treatment course for latent tuberculosis infection that otherwise might have been recommended prior to the advent of IGRAs.