Interferon-gamma release assays (IGRAs) are blood tests used to detect Mycobacterium tuberculosis, the bacteria that causes tuberculosis (TB). These tests measure the immune response to specific TB proteins, helping to identify if a person has been infected with the bacteria, even if they do not show symptoms. IGRAs are particularly useful for diagnosing latent TB infection, which means the bacteria are present in the body but inactive. Unlike traditional skin tests, IGRAs do not require a follow-up visit and are not affected by prior vaccination with BCG or by most other infections, making them a reliable option for screening.