Tuberculosis Guides

Tuberculosis (TB) testing looks for evidence of infection with the bacteria that cause TB. The two common approaches are a blood test, which measures the immune response to TB proteins, and a skin test. Blood testing has become more widely used because it requires only a single visit and a single sample.

A TB test cannot tell the difference between a latent infection, in which the bacteria are present but inactive, and active TB disease, which causes symptoms and can be spread to others. That distinction requires a clinical evaluation, imaging, and sometimes further lab work.

TB testing is often required for certain jobs and school programs, and for people who have traveled to or lived in areas where TB is more common, or who have a weakened immune system.

Because TB can remain inactive for years, a positive test often reflects exposure at some point in the past rather than current illness. A positive result usually leads to further evaluation rather than a diagnosis on its own.

Each guide explains how the test is performed, what type of sample is used, when results are available, and how a result is typically followed up. Screening is safe and widely available, and no special preparation is usually needed before a TB blood test.

These guides are educational only and are not medical advice. If you have symptoms such as a persistent cough, fever, or weight loss, or if you may have been exposed to TB, seek care from a qualified healthcare provider promptly.