for Veterans and the Public
TB is short for tuberculosis, a disease that people with HIV are at higher risk for getting. Most people who are exposed to TB don't get sick from it-the bacteria can live in the body for a long time without causing disease. But some people develop tuberculosis disease, and this is more likely if the immune system is weakened.
There are two types of tests for exposure to TB. One is the TB skin test (also known as PPD), which requires the person to return to the clinic 2-3 days after the skin test is placed for the test to be interpreted. The other is a blood test called an interferon-gamma release assay (IGRA) (QuantiFERON and TSpotTB are two examples of IGRA blood tests).
HIV can make both types of tests less reliable for diagnosing tuberculosis, particularly if the immune system is weak. Neither of these tests can tell the difference between exposure to TB (where a person is not sick with TB) and active TB (where a person is sick with TB). If a person has been exposed to TB, treatment can reduce the risk of becoming sick with TB in the future.