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Friday, October 24, 2014
Positive Quantiferon TB Test
I am a healthcare worker. I converted to + ppd more than 10 years ago, I was treated with INH for 6 months. I recently had a + Quantiferon TB test. I have a neg chest xray. Do I need a further workup?
As a healthcare worker with a history of a positive TB skin test and a normal CXR, you will likely be required (at a minimum) to have annual screening for symptoms of TB. The CDC no longer recommends periodic CXR's for TB screening. Your state's Department of Health most likely has guidelines for TB screening for health care workers. I suspect most states do not yet incorporate results of the Interferon Gamma Release Assay for TB (IGRA-TB), such as the Quantiferon Gold test, into their TB screening guidelines. When we have more experience using the IGRA's, we may learn what it means in terms of your risk for reactivating TB in the future to have a + IGRA after taking 6 months' INH in the past.
Lisa A Haglund, MD
Associate Professor of Clinical Medicine
College of Medicine
University of Cincinnati