Abstract :
Latent tuberculosis infection (LTBI) affects a substantial portion of the global population and represents a key reservoir for future active tuberculosis (TB) cases. Early and accurate detection of LTBI is essential for TB control and elimination strategies, particularly in high-burden countries like India. The Tuberculin Skin Test (TST) and Interferon-Gamma Release Assays (IGRAs), including QuantiFERON-TB Gold and T-SPOT.TB, are the principal diagnostic tools for LTBI. TST is simple, low-cost, and suitable for peripheral healthcare settings, but its specificity is limited by prior BCG vaccination and environmental non-tuberculous mycobacteria. IGRAs provide improved specificity by detecting T-cell responses to Mycobacterium tuberculosis-specific antigens, offer single-visit testing, and are particularly useful in immunocompromised or BCG-vaccinated populations. This review evaluates the diagnostic principles, comparative performance, predictive value for progression to active TB, operational challenges, cost-effectiveness, and guideline-based recommendations for TST and IGRA. Emphasis is placed on India-specific implementation strategies, including tiered diagnostic approaches, quality assurance, and use in special populations, highlighting the potential of these tools to optimize LTBI screening and accelerate progress toward national TB elimination goals.
Keyword :
Latent TB infection, TST, Mantoux test, IGRA, QuantiFERON, T SPOT.TB, Diagnostic accuracy, Predictive value, Guideline recommendations.