A positive PPD (Purified Protein Derivative) test, also known as a tuberculin skin test or Mantoux test, is a diagnostic tool used to determine whether a person has been exposed to the bacterium Mycobacterium tuberculosis, which causes tuberculosis (TB). The test involves injecting a small amount of purified protein derived from the TB bacteria just beneath the skin of the forearm.

Here's how the test works and what a positive result might indicate:

1. Administering the Test: A healthcare professional administers the PPD test by using a small needle to inject a tiny amount of the TB protein, called tuberculin, into the top layer of the skin on the forearm. This creates a small bump or welt at the injection site.

2. Reading the Test: The person who received the test must return to the healthcare facility within 48 to 72 hours after the injection to have the test site examined. The healthcare provider will measure the size of the bump or welt and assess its appearance.

3. Interpreting the Results: The reaction at the injection site is measured in millimeters of induration (raised, hardened area). A positive PPD test is generally defined as an induration of a certain size, which can vary based on the individual's risk factors, age, and region. A positive result indicates exposure to the TB bacteria but does not necessarily mean that the person has active TB disease.

4. Further Evaluation: A positive PPD test requires further evaluation to determine if the exposure was due to a latent TB infection or active TB disease. Additional tests, such as chest X-rays, sputum cultures, and clinical evaluations, might be conducted to differentiate between these two possibilities.

It's important to note that a positive PPD test indicates exposure to TB but doesn't necessarily indicate active disease. Many people with a positive PPD test have latent TB infections, which means the bacteria are present in their bodies but are inactive and not causing illness. However, some individuals with a positive PPD test might have active TB disease and require treatment to prevent the disease from progressing and to reduce the risk of transmission to others.

The interpretation of PPD test results and the recommended actions vary depending on a person's individual risk factors, such as their age, medical history, and exposure to individuals with active TB disease. Healthcare professionals will consider these factors to determine the appropriate course of action, including further testing and potential treatment.

It's important to consult with a healthcare provider if you have questions or concerns about a positive PPD test or TB exposure. Additionally, medical guidelines and practices might have evolved beyond my last knowledge update in September 2021, so it's recommended to seek information from current medical sources.

свернуть