Results of a tuberculosis-specific IFN-gamma assay in children at high risk for tuberculosis infection.

The specificity of the tuberculin skin test (TST) for the diagnosis of latent tuberculosis infection (LTBI) is adversely affected by bacille Calmette-Guérin (BCG) vaccination and infection with non-tuberculous mycobacteria. Interferon-gamma release assays (IGRAs) using TB-specific antigens promise higher specificity. We compared a new IGRA and TST in 184 schoolchildren at high risk for LTBI. The IGRA and TST were positive in 33.2% and 43.5% of the children, respectively (P < 0.001). If studies confirm that this difference is due to higher specificity of this IGRA, it may have an important role to play in the diagnosis of LTBI and identification of children at true risk for TB.