Quantiferon-TB

QuantiFERON-TB Gold Plus Testing

The QuantiFERON-TB Gold Plus (QFT-Plus) test is a modern, highly accurate blood test used to detect latent and active tuberculosis (TB) infections. It is an alternative to the traditional tuberculin skin test (TST) and offers several advantages, including single-visit testing and results that are not affected by prior BCG vaccination.

How It Works

The QuantiFERON-TB test is an interferon-gamma release assay (IGRA). It works by measuring the immune system's response to specific proteins from the TB bacteria.

1. Blood Collection: A small blood sample is collected into specialized tubes. These tubes contain specific antigens that stimulate the immune cells (T-cells) in your blood.
2. Incubation: The blood samples are incubated, during which the T-cells from individuals who have been exposed to TB will release a protein called interferon-gamma.
3. Laboratory Analysis: The amount of interferon-gamma released is measured in a laboratory to determine if your body has had an immune response to the TB bacteria.

Why Choose QuantiFERON-TB?

• Single Visit: Unlike the skin test, which requires a return visit to have the result read, the QuantiFERON-TB test only requires one visit for the blood draw.
• High Accuracy: The test is highly specific and sensitive, meaning it is very effective at correctly identifying people with or without a TB infection.
• Unaffected by BCG Vaccine: Results are not affected by a previous BCG (Bacille Calmette-Guérin) vaccination, which can often cause a false positive result on a skin test.

Who Should Get Tested?

This test is typically recommended for individuals who:

• Have been in close contact with someone with active TB.
• Are at an increased risk for TB infection (e.g., healthcare workers, people who have lived in countries with high TB rates).
• Require a TB test for immigration, employment, or school entry.
• Have received a BCG vaccination in the past.

How to Prepare for the Test

No special preparation is needed for a QuantiFERON-TB test. You do not need to fast, and you can eat and drink as you normally would before your blood draw.

Understanding Your Results

Your results will be reported as either:

• Positive: A positive result indicates that you have been infected with TB bacteria. It does not distinguish between latent TB infection and active TB disease. A positive result will require further evaluation by a healthcare provider, which may include a chest x-ray and other medical assessments.
• Negative: A negative result means it is unlikely that you have a TB infection.
• Indeterminate: This result means the test could not be completed, often due to a compromised immune system or other factors. An indeterminate result may require a retest or further consultation with a healthcare provider.