Latent Tuberculosis Infection

Latent tuberculosis infection (LTBI) is a subclinical infection with Mycobacterium (M.) tuberculosis. Children and immunosuppressed individuals due to pathologic conditions or therapeutic procedures are at a high risk of reactivation of LTBI to active disease compared to general population and require timely identification. The diagnosis of LTBI is based on the measurement an adaptive immune response against M. tuberculosis. The use of tuberculin skin test (TST) has been associated with a number of interfering factors that cause false-positive or false-negative test results. The new ex vivo whole blood tests determining interferon-gamma (IFN-γ) released from T-lymphocytes (interferon-gamma release assays, IGRAs) upon stimulation with M. tuberculosis specific antigens. The introduction of IGRAs to routine clinical practice has improved the diagnosis of LTBI, but recommendations and guidelines for the diagnosis of LTBI are not consistent between different European countries. Therefore, European centre for disease prevention and control developed guidance document based on the up-to-date scientific evidence. Novel concepts of IGRAs and new studies should be designed so as to provide answers to all open questions.