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Tuberculin Test

Tuberculin Test is a skin test used to determine whether or not a child has been infected with TUBERCULOSIS (TB); the test is used to diagnose suspected cases of tuberculosis, prior to vaccination against the disease. During the test, the skin is first disinfected and a small dose of tuberculin (a protein extract of the tuberculosis bacilli) is introduced into the skin in one of a variety of ways.

In the Mantoux test the extract is injected into the skin with a needle; in the Sterneedle test the extract is dropped on the forearm as a spring-loaded instrument circled with a sharp prong forces the tuberculin into the skin. After 48 to 72 hours, the skin is inspected at the site; if the skin is unchanged, the reaction is negative, indicating the person has never been exposed to tuberculosis and has no immunity.

Skin that becomes red, hard, and raised after the injection indicates that the person has been exposed to tuberculosis, either through vaccination or infection.