The TDF Laboratory is now offering a new diagnostic TB test, called QuantiFERON-TB Gold Plus.  It is a type of Interferon-Gamma Release Assay, commonly known as IGRA, that can help detect TB infection.  It is a simple blood test that can be used as a modern alternative to tuberculin skin test (TST), and it can also be used to confirm a positive skin test result.  Compared with tuberculin skin test, QuantiFERON (QFT) provides greater accuracy and a more reliable result while only requiring a single patient visit.  More importantly, QuantiFERON is not affected by prior Bacille Calmette-Guerin (BCG) vaccination.

A positive result in QuantiFERON-TB Gold Plus indicates likelihood of infection, but it does not necessarily mean that a patient has active TB.  Despite QFT being highly specific and sensitive, it cannot distinguish between active TB disease and latent TB infection.  Active tuberculosis is still diagnosed through a combination of laboratory tests, X-rays, and other clinical evaluations.