Principles and clinical applications of interferon-gamma release assays in latent tuberculosis diagnosis

Latent tuberculosis (TB) refers to a state in which an individual is infected with Mycobacterium tuberculosis but shows no clinical symptoms. The World Health Organization estimates that 23% of the global population has latent TB, which poses a significant public health challenge owing to the risk of progression to active TB. Diagnosis of latent TB involves tests, such as the tuberculin skin test (TST) and interferon-gamma release assays (IGRAs). The TST can yield false positives due to prior Bacillus Calmette-Guérin (BCG) vaccination, whereas IGRAs offer higher specificity and are unaffected by BCG vaccination. Factors, such as age and recent vaccinations, can affect test performance. Treatment with isoniazid and rifampicin is recommended for those diagnosed, as it has been shown to prevent 80%-90% of active TB cases, although more extended follow-up studies are needed to confirm its long-term efficacy. Indeterminate IGRA results, especially in immunocompromised individuals, add complexity to the diagnosis and treatment decisions, highlighting the need for careful interpretation. Further research is vital to improve the diagnostic accuracy, interpretation, and treatment effectiveness.