Abstract
Despite numerous published papers, diagnosis of latent tuberculosis infection (LTBI) in children is still an undefined area. The importance of this topic lies in the fact that one third of the world's population is infected with Mycobacterium (M.) tuberculosis. The majority of infected individuals are LTBI cases which make a reservoir for future active tuberculosis (TB) patients. The gold standard for LTBI detection is still undetermined and this is due to the effect of various confounding factors on existing diagnostic tests. Until a decade or so ago, throughout the last century, tuberculin skin test (TST) was the only diagnostic test for LTBI. Due to scientific advances, new in vitro assays, interferon-gamma release assays (IGRAs) were discovered recently. The sensitivities of IGRAs are a bit better than those of TST, while great progress has been made in increasing the specificity of IGRA relative to TST. Nevertheless, in the diagnosis of LTBI in children, TST still has some advantages. However, generations of IGRAs have brought many diagnostic advantages that are emphasized in this review. In a difficult procedure of diagnosing LTBI in children, performance of IGRA could be the key factor in making decision whether to use preventive therapy or not.