Screening for Latent TB: A Review of Interferon-Gamma Release Assays and the Tuberculin Skin Test (TST)

Authors: Dr. Saurabh Chhotalal Norris, Binda Prakashbhai Pipaliya, Himani Bhardwaj Pandya, Rachana Dhirubhai Patel, Dr. Tanuja Bakul Javadekar

DOI: 10.18231/j.ijirm.12686.1943244482

Keywords: Latent TB infection, TST; Mantoux test, IGRA, QuantiFERON, T SPOT.TB, diagnostic accuracy, predictive value, guideline recommendations

Abstract: Tuberculosis (TB) remains a major concern in global health, with latent tuberculosis infection (LTBI) estimated to affect nearly a quarter of the world’s population. Early and accurate diagnosis of LTBI plays a vital role in breaking the transmission chain and progressing toward TB elimination. The Tuberculin Skin Test (TST or Mantoux test) and Interferon-Gamma Release Assays (IGRAs), including QuantiFERON-TB Gold and T-SPOT.TB, are widely used for LTBI screening. However, the TST has limitations due to cross-reactivity with Bacille Calmette-Guérin (BCG) vaccination and environmental non-tuberculous mycobacteria. In contrast, IGRAs offer improved specificity by detecting immune responses to antigens specific to Mycobacterium tuberculosis, such as ESAT-6 and CFP-10. This review critically evaluates both diagnostic methods by analyzing their underlying principles, comparative performance in different populations, and predictive value for progression to active disease, implementation challenges, and relevance to current international and national TB control guidelines.