<s>[INST] Is there a test for the detection of TB infection (“LTBI” or “latent TB”)? [/INST] There are several methods to detect TB infection, broadly divided into tuberculin skin tests and blood tests. A tuberculin skin test (TST), which has been used to detect TB infection for over 100 years, requires an intradermal injection of a small amount of purified protein derivative (PPD) into the skin. In 48-72 hours, the resultant induration is measured. More recently, blood based tests, referred to as interferon gamma release assays (IGRAs), have been introduced. The technology of the T-SPOT.TB test, an IGRA, is based on the release of interferon-gamma secreted by individual effector T cells (both CD4 and CD8) after being stimulated by TB specific antigens. Source: T-SPOT ASIA. Link: https://tspot.asia/resources/frequently-asked-questions/. Field: Lung Disease. Disease: Tuberculosis </s>