CDC Recommends New TB Blood Test Believed To Yield Fewer False Positives Than Skin Test
CDC on Thursday recommended the new tuberculosis blood test QuantiFERON-TB GOLD, saying it is less likely to produce false-positive results and is more convenient than the 100-year-old tuberculin skin test, the AP/Seattle Post-Intelligencer reports. With the QuantiFERON test, patients are required to have their blood drawn once and are notified of their results when they become available, which can be as soon as the next day. In comparison, the skin test requires health workers to inject tuberculin under the patient's skin, and patients must return after two to three days so health workers can examine the swelling to determine if the test is positive. In addition, various bacteria not related to TB, previous TB vaccinations, and HIV/AIDS and other immune deficiency conditions often trigger false-positive results from the skin test. Although more studies need to be conducted, QuantiFERON -- which is manufactured by Australian medical technology firm Cellestis -- yields fewer false positives, CDC said (Stobbe, AP/Seattle Post-Intelligencer, 12/15). QuantiFERON also detects immune responses to proteins associated with TB and therefore can detect infection even if symptoms have not developed, according to Cellestis spokesperson Marcy Pozzo. She added that the tuberculin skin test has a higher rate of false positives in people who are asymptomatic(GlobalHealthReporting.org, 3/16). CDC's recommendations for using the QuantiFERON test and updated guidelines for investigating contacts of people with infectious TB are available in the Dec. 16 issue of MMWR Recommendations and Reports (MMWR Recommendation and Reports, 12/16).
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