Tuberculosis is an infection caused by the bug mycobacterium tuberculosis. People are screened for TB with the skin prick test that is looked at a few days later for reaction. If redness and swelling develop at the skin prick site, that means you have been exposed to TB, and your body has developed an immune response to fight it off. You may or may not have an active TB infection.
Now there is a blood test “QuantiFERON-TB Gold In-tube assay” (QFT) that seems to be more accurate in diagnosing active TB infection. This blood test is too new to be in wide use. More experience is needed in order to understand its results. The skin prick test is still usually the screening test of choice. There is also a vaccine shot (called H:4IC31) being tested to prevent TB altogether.
Some people (often from Africa) received a TB vaccine called bacille Calmette-Guerin (BCG) in childhood. The BCG seems to offer some protection from TB. It also usually makes you have a positive TB skin test. Some of our clients who had the BCG vaccine in Africa are being tested by the new blood test.
Tuberculosis can be treated and often cured with pills. You can acquire TB by droplets from a person who has active TB.
Symptoms of TB include chronic cough, weight loss and fever. If you have lived with someone who had TB, make sure your doctor knows and that you are tested appropriately.
Information is from New England Journal of Medicine, 7/22/2018.