/How do they test for TB?

The TB skin test is used to find out if you have TB infection. A small amount of testing fluid is injected just under the skin on the underside of the forearm. After two or three days, you must return to have your skin test read by a health care worker to determine if it is positive or negative. A positive result usually means that you have been infected by someone with active TB disease. If you miss the skin reading, the entire test will have to be given again.

Another test is a blood test. The QuantiFERON®-TB Gold In-Tube test (QFT-G) is a whole-blood test to aid in diagnosing Mycobacterium tuberculosis infection, including latent tuberculosis infection (LTBI) and tuberculosis (TB) disease.