Various diagnostic means are available to highlight TB infection and TB disease:
TUBERCULIN SKIN TEST (TST) TO DIAGNOSE BK INFECTION
Also called intradermal or Mantoux test, this test allows to know if a person is infected or not by the bacillus of Koch.
It consists of injecting tuberculin into the dermis of the forearm and seeing, 3 to 5 days later, if a reaction appears. This one indicates probable contamination by tubercle bacilli.
Vaccination with BCG may also cause a reaction during the test but is not a contraindication.
IGRA tests are more expensive blood tests that offer an alternative to TCT, but they are not currently used routinely in USA.
TST and IGRA tests are the only way to detect latent TB infection.