Description
The QuantiFERON®-TB Gold Plus (QFT-Plus) is an FDA-approved blood test used to screen for Mycobacterium tuberculosis, the bacteria that cause tuberculosis (TB). This test identifies an immune response to TB in the blood, making it one of the most reliable alternatives to the traditional tuberculin skin test (TST).
- Highly Specific – Up to 99% specificity in detecting TB infection
- Single Visit – Requires only one blood draw, unlike the TST which requires follow-up
- Fasting – Not required
What is Tuberculosis (TB)?
TB is a bacterial infection that primarily affects the lungs, but it can also damage the brain, kidneys, and spine. It spreads through airborne particles when a person with active TB coughs, sneezes, talks, or sings.
TB can exist in two forms:
- Latent TB infection – Bacteria are in the body but inactive; no symptoms and not contagious
- Active TB disease – Bacteria are active, causing symptoms and can spread to others
How the Test Works
This blood test detects the release of interferon-gamma (IFN-γ) when white blood cells are exposed to TB-specific antigens. A positive result suggests latent or active TB infection and may require further clinical evaluation.
Who Should Get Tested?
This test is recommended for individuals who:
- Have spent time with someone who has TB
- Work or live in high-risk environments (healthcare facilities, shelters, correctional institutions)
- Were born in or frequently travel to countries with high TB prevalence
- Have conditions that weaken the immune system (e.g., HIV/AIDS, autoimmune disorders)
- Are children under age 5 or adults over age 55
- Were previously treated inadequately for TB
- Have alcohol or substance use disorders
