What is the most commonly used test to determine TB infection?

The Mantoux Tuberculin Skin Test (TST) is considered the most commonly used method to determine tuberculosis (TB) infection. This test involves injecting a small amount of purified protein derivative (PPD) into the skin and observing the reaction after 48 to 72 hours. A significant induration at the injection site indicates exposure to the TB bacteria, thus suggesting potential infection.

The widespread use of the Mantoux test is due to its efficacy, ease of administration, and ability to evaluate large groups of people, especially in settings like schools, healthcare facilities, and detention centers. It has been a standard screening tool for TB for many years.

While other tests, such as the QuantiFERON-TB Gold Test, are also available and becoming more widely used, particularly for specific situations like screening individuals who have received the BCG vaccine, the TST remains the primary method used due to its historical significance and infrastructure for administration. Additionally, X-ray tests and sputum cultures are diagnostic tools that confirm active TB disease rather than simply indicating infection status.