July 1, 2008

New TB Test Identifies Drug Resistance Faster

By Steve Sternberg

Rapid DNA tests that can save thousands of lives by cutting delays in diagnosis of drug-resistant tuberculosis from two months to two days will be rolled out in 16 countries fighting twin epidemics of HIV and TB, health officials said Monday.

Current TB tests are more than a century old. The new tests, which apply DNA "fingerprinting" techniques to TB for the first time, mean that patients who show evidence of TB infection can now be tested and treated quickly rather than waiting while a stubborn infection turns lethal.

"We are going to tell the world that they should adopt this test as rapidly as possible," says Mario Raviglione, director of the Stop TB Department of the World Health Organization, noting that this is the first time WHO has issued such an endorsement.

The test has not yet been approved by the Food and Drug Administration, though doctors in the USA diagnose dozens of drug-resistant TB cases every year. "There's great interest in the U.S.," says Richard O'Brien of FIND Diagnostics, which played a key role in developing the new test.

Drug-resistant TB has lost its vulnerability to the first-line drugs isoniazid and rifampin. About 5% of the nearly 10 million people diagnosed with TB every year have drug-resistant forms of the disease and are much more difficult to treat.

Treatment is often delayed by the difficulty of diagnosing drug resistance, which can take two to three weeks in the USA and two to three months in developing countries. Each year, doctors diagnose nearly half a million cases of drug-resistant TB, and more than 130,000 patients die. Only about 2% of cases worldwide are diagnosed and treated promptly because lab services are lacking.

A consortium of public health groups said Monday that they would try to increase that total to 15% over the next four years. They plan to create and update laboratory facilities, train staff, and make the new rapid DNA tests widely available. They will cost about $5 each, O'Brien says.

The initiative's four-year start-up funding of $26.1 million will be supplied by UNITAID, a global drug-purchasing facility founded by Brazil, Chile, France, Norway and the United Kingdom to provide low-cost drugs to poor countries. India, China and Russia will fund their own programs, with help from other donors.

Two versions of the test are available. The new initiatives will rely on one made by Hain Lifescience in Germany, which detects resistance to isoniazid and rifampin. Innogenetics of Belgium makes a test that detects only rifampin resistance.

The test was tried in one of the world's poorest countries, Lesotho, where 25% of the population has HIV and which has a TB rate of 500 per 100,000. By last year, it was in widespread use.

"If you can do it in Lesotho, you can do it anywhere," O'Brien says. (c) Copyright 2008 USA TODAY, a division of Gannett Co. Inc. <>