From the Guidelines
A positive QuantiFERON test indicates that you have been infected with tuberculosis (TB) bacteria, but it doesn't necessarily mean you have active TB disease. This test measures your immune system's reaction to TB proteins and is more specific than the traditional skin test 1. If you have a positive result, you should see a healthcare provider promptly for further evaluation, including a chest X-ray and physical examination to determine if you have latent TB infection (LTBI) or active TB disease.
Key Considerations
- The risk for progression to TB disease varies, with the greatest risk occurring within the first 2 years after infection 1.
- Certain clinical conditions, such as HIV infection, diabetes mellitus, and use of therapeutic agents that antagonize the effect of cytokine tumor necrosis factor (TNF-), are associated with increased risk for progression from LTBI to TB disease 1.
- For LTBI, the standard treatment is usually isoniazid (INH) 300mg daily for 6-9 months, or a shorter regimen of isoniazid plus rifapentine weekly for 12 weeks.
- If active TB is diagnosed, you'll need a combination of multiple antibiotics (typically isoniazid, rifampin, ethambutol, and pyrazinamide) for at least 6 months 1.
Importance of Treatment
- It's crucial to complete the full course of treatment even if you feel better, as incomplete treatment can lead to drug-resistant TB.
- The positive test result occurs because your body has developed T-cells that recognize TB proteins, releasing interferon-gamma which is detected in the blood sample during testing 1.
Next Steps
- Consult a healthcare provider to determine the best course of action based on your individual situation and risk factors.
- Adhere to the recommended treatment regimen to minimize the risk of progression to active TB disease and prevent drug resistance.
From the Research
Positive Quantiferon Test
- A positive Quantiferon test indicates the presence of latent tuberculosis infection (LTBI) 2
- The risk of developing active tuberculosis (TB) in individuals with a positive Quantiferon test result is low, with a probability of clinical breakdown of 0-0.0104/person-year 2
Treatment of Latent Tuberculosis Infection
- The mainstay therapy for LTBI is a 9-month regimen of daily isoniazid (9H) 3
- Alternative regimens include:
- These regimens have varying efficacy, safety, and completion rates, with 3HP and 4 months of rifampin showing promise as shorter and safer alternatives to 9H 3, 4, 5, 6
Efficacy and Safety of Treatment Regimens
- 3HP has been shown to have less hepatotoxicity and better efficacy and completion rates compared to 9H 4
- 4 months of rifampin has been found to have significantly better completion and less toxicity compared to 9H 3
- 3-month isoniazid-rifapentine has been determined to be equal to other LTBI regimens in effectiveness and has higher treatment completion rates 5