Use of Interferon-Gamma Release Assays to Calculate the Annual Risk of Tuberculosis Infection

The objective was to assess the annual risk of tuberculosis infection by means of tuberculin skin testing (TST) in children, evaluating whether QuantiFERON-TB Gold In-Tube (QFN-G-IT) could improve the accuracy. On the basis of the positive TST results, the global annual incidence was estimated at 0.78%, with an increase in the prevalence from 0.64% to 1.68% in 2 years. However, QFN-G-IT was only positive in 6 of the 25 children with positive TST. The confirmation of the positive TST results by QFN-G-IT provided more accurate annual incidence estimation.