Faster Detection of TB May Be on the Horizon

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FRIDAY, Sept. 25 (HealthDay News) -- A new test can rapidly identify active tuberculosis in people who've had negative sputum tests, say European researchers.

In about half of all people with active TB, the disease-causing bacterium can't be identified using sputum tests. Because of this, new diagnostic tests are needed to help control the spread of TB, the researchers said.

"In this study, we showed that a differentiation between active pulmonary tuberculosis and [latent TB infection] is possible by the ELISpot test," Dr. Christoph Lange, principal investigator of the Tuberculosis Network European Trials group study, said in a news release from the American Thoracic Society.

The study included 347 people, including 71 with active pulmonary TB. In the 71, ELISpot results were positive in 65 cases (91.5%). An ELISpot test detects active TB by comparing the frequencies of TB-specific T-lymphocytes in the blood with those in the lung, with results in a day. Current testing can take several weeks to get results, according to background information in the news release.

The findings show that a positive ELISpot test result is highly indicative of active TB, whereas a negative result almost excludes active TB, Lange said.

The study is published in the Oct. 1 issue of the American Journal of Respiratory and Critical Care Medicine.

About one-third of the world's population is infected with the bacterium that causes TB, M. tuberculosis, but only 10 to 20% of those who are infected will develop active TB, according to the World Health Organization. Active TB is the seventh-leading cause of death worldwide.

-- Robert Preidt

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SOURCE: American Thoracic Society, news release, Sept. 23, 2009