Nonspecific reaction to test for tuberculosis Save

Nonspecific Reaction to Test for Tuberculosis

When it comes to diagnosing tuberculosis (TB), there is no single test that can confirm the presence of the disease. Instead, healthcare providers often use a combination of tests and evaluations to make a diagnosis. One such test is the tuberculin skin test (TST), which is also known as the Mantoux test.

The TST involves injecting a small amount of purified protein derivative (PPD) under the skin of the forearm. After 48-72 hours, the healthcare provider will measure the size of the resulting bump. A positive reaction to the TST means that the person has been infected with the bacteria that cause TB, but it does not necessarily mean that they have active TB disease.

However, there are also instances where the TST may produce a false positive result. This means that the test indicates that a person has TB when they actually do not. This can happen for a variety of reasons, including:

1. Prior BCG vaccination: BCG is a vaccine that is used in many countries to prevent TB. However, the vaccine can also cause a positive reaction to the TST, even in people who have never been infected with TB before.
2. Other mycobacterial infections: There are other types of mycobacteria that can cause infections similar to TB. These infections can also cause a positive reaction to the TST.
3. Incorrect administration of the test: If the TST is not administered correctly, it can produce a false positive result.
4. Immune system disorders: People with certain immune system disorders, such as HIV, may have a false positive reaction to the TST.

It is important to note that a false positive result from the TST does not mean that a person has active TB disease. However, it may lead to further testing and evaluation to determine if the person has been infected with TB or if there is another reason for the positive result. If you have questions or concerns about the TST or TB testing in general, talk to your healthcare provider.