Tuberculosis is a communicable disease caused by infection with M.tuberculosis (MTB)complex organisms (M. tuberculosis, M. bovis, M. africanum), which typically spread to new hosts via airborne droplet nuclei from patients with respiratory tuberculosis disease. It is one of the most important health threatening problems worldwide. The World Health Organization estimates that one third of the worldâs population is infected with M.tuberculosis. Each person carrying latent TB infection (LTBI) has approximately a 10% chance of progressing to active disease. Interferon Gamma Release Assay (IGRA) measure a personâs immune reactivity to M.tuberculosis. T lymphocytes from most persons that have been infected with M.tuberculosis will release IFN-Î³ when mixed with special antigens derived from M.tuberculosis. IGRA is whole-blood test that can aid in diagnosing Mycobacterium tuberculosis infection, including both latent tuberculosis infection (LTBI) and tuberculosis (TB) disease.