Final answer:
The tuberculin test for tuberculosis, also known as the Mantoux test, is used to identify a person's past or present infection based on a positive skin reaction showing cellular hypersensitivity to TB proteins.
Step-by-step explanation:
The test that is used to determine past or present infection based on a positive skin reaction is known as the tuberculin test, which is specifically designed for the diagnosis of tuberculosis (TB). This form of diagnosis assesses delayed hypersensitivity. The procedure involves injecting bacterial proteins from Mycobacterium tuberculosis into the skin. A positive reaction is usually observed a couple of days later and is characterized by a raised red area, firm to the touch, known as an induration, resulting from a cellular infiltrate. The induration is a response composed mainly of activated macrophages. A positive tuberculin test indicates that the individual has had prior exposure to TB and that their cellular immune system responds accordingly.
However, a positive test does not necessarily confirm an active TB infection. It could also indicate a past infection or latent TB due to memory T cells that were produced either during a current infection or from previous exposure. The Mantoux test, which involves a single subcutaneous injection of purified tuberculin material, is the modern variant of this hypersensitivity test. The test's outcome must be interpreted with caution and alongside clinical symptoms or radiographic findings to confirm true infection.