TuberkulinHauttests

TuberkulinHauttests, also known as tuberculin skin tests orTSTs, are diagnostic procedures used to detect latent tuberculosis infection. The most common methods are the Mantoux test and the older Pirquet test. The Mantoux test involves injecting a small amount of purified protein derivative (PPD) tuberculin intradermally into the forearm. The Pirquet test, now less common, involved scratching the skin and applying tuberculin to the abrasion.

After 48 to 72 hours, the injection site is examined for a raised, hardened area called an induration. The size of this induration determines the test result. A positive result indicates that the person has been infected with tuberculosis bacteria at some point, but it does not distinguish between latent infection and active tuberculosis disease. False positives can occur due to prior BCG vaccination or infection with non-tuberculous mycobacteria. False negatives can result from impaired immune function or recent infection.

TSTs are a crucial tool in tuberculosis screening programs, particularly for individuals at high risk, such as healthcare workers, immigrants from high-prevalence countries, and those in close contact with infectious TB cases. A positive TST warrants further investigation, often including a chest X-ray and sputum tests, to rule out active disease and determine if preventive treatment is necessary for latent infection. The interpretation of TST results requires careful consideration of individual risk factors and exposure history.