Is there a test for latent TB infection?
Until recently the only way of testing for latent TB was through the use of the Tuberculin Skin Test (TST). This test is over one-hundred years old and involves injecting a small amount of killed TB bacteria into the skin and measuring any bump that forms 2-3 days later. The test can often be inaccurate, particularly in those people who have been vaccinated against TB (with the BCG vaccine) or people who have a suppressed immune system. These inaccuracies can occur in up to half of the skin tests done. The usual skin test used is called the Mantoux test.
