What is the purpose of a Mantoux test?

The Mantoux test, also known as the tuberculin skin test, is specifically designed to screen for tuberculosis infection. It involves injecting a small amount of purified protein derivative (PPD) into the skin and observing the reaction after 48 to 72 hours. The primary purpose of this test is to identify individuals who have been exposed to the tuberculosis bacteria, leading to an immune response.

When the immune system has been exposed to the bacteria that cause tuberculosis, it reacts to the protein in the test. A positive reaction, indicated by a raised, reddened area at the injection site, suggests that the individual may have been infected with tuberculosis, although it does not confirm that they have an active disease. This makes the Mantoux test a crucial tool for public health, especially for screening in populations at higher risk for tuberculosis.

In contrast, the other options refer to different diagnostic assessments that do not involve screening for tuberculosis infection. Assessing lung capacity and determining oxygen levels are performed through pulmonary function tests and arterial blood gas analyses, respectively, while diagnosing asthma typically involves evaluating symptoms and conducting a similar set of pulmonary function tests. These tests serve different purposes in respiratory health, distinguishing them from the specific role of the Mantoux test.