Indirect Blood Test for Tuberculosis

A new test for tuberculosis (TB) detects immune responses to specific proteins associated with TB infection. The test has been cleared by the U.S. Food and Drug Administration (FDA).

Called QuantiFERON-TB Gold, the test is designed as a new alternative to the tuberculin skin test (TST). Clinical data have demonstrated that the new test offers superior specificity (> 99%) over the TST. The TST is highly subjective, has poor reproducibility, and requires two patient encounters: one to inject the patient and a second to interpret the inflammation it may produce. In contrast, the QuantiFERON test measures immune responses to peptides that simulate tuberculosis proteins that are not present in the BCG vaccine or most nontuberculosis mycobacteria. The QuantiFERON technology was initially developed by Australian researchers for the detection of TB in cattle.

The lower cost of performing the new test and the elimination of false-positive results are expected to result in cost savings for hospitals and clinics. For patients born in the United States, the false-positive rate due to nontuberculosis infections can be as much as 50% of all TST responses. For other patients, cross reactivity to past TB vaccination with Bacillus Calmette-Guerin (BCG) is a common cause of false-positive TST responses.

TB is responsible for more than two million deaths each year. The U.S. Centers for Disease Control and Prevention (CDC, Atlanta, GA, USA) estimate that 10-15 million U.S. residents are infected with TB in its latent phase.

"There are numerous markets where our test will have a significant impact, including prisons and jails, public health TB programs, and for screening recent immigrants, healthcare workers, and military personnel,” noted Tony Radford, Ph.D., CEO of Cellestis, Inc. (Valencia, CA, USA), which is commercializing the QuantiFERON test.





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