The New York Times - July 1, 2008
Lawrence K. Altman

Multiple-drug-resistant TB, or MDR-TB, is a growing public health problem in the world. Five percent of new TB cases are resistant to first-line drugs. That is 450,000 of the 9 million new TB cases that are detected each year, WHO says.

In the United States, the prevalence of drug-resistant tuberculosis among foreign-born TB patients has been about 1.5 percent, roughly three times the percentage among American-born patients with TB.

"The new test is revolutionary," said Dr. Mario Raviglione, WHO's director of tuberculosis control.

Detecting cases rapidly and accurately is a major source of delay in tuberculosis control. In most developing countries, cases cannot be detected easily or at all, causing lags in starting proper treatment that can lead to a patient's death and the further spread of resistant strains.

The new test was described for reporters by telephone on Monday by officials from WHO, a U.N. agency, and three other international health groups: the Stop TB Partnership, Unitaid and the Foundation for Innovative New Diagnostics (FIND).

The TB test, called a line probe assay, costs less than $8 and detects mutations in bacterial DNA linked to drug resistance.

It is based on the same laboratory methods that scientists have used to determine parentage and detect certain genetic diseases, said Dr. Richard O'Brien, an official of FIND.

Drug-resistant TB, like drug-sensitive TB, can be transmitted by an infected individual in droplets through coughing, sneezing, singing and other activities.

It may require two years of treatment with drugs that are much more costly than the first-line regimen. Technically difficult surgery may also be required.

Health officials have sounded alarms because they believe TB could reach the point where, without efforts like the new laboratory test to help stop the spread of the disease, most new cases in some countries would be resistant to many drugs.

A concern is the potential for outbreaks of MDR-TB to evolve into those of the even deadlier XDR-TB.

Raviglione and other officials urged use of the test everywhere, particularly in poor countries where HIV is also epidemic. HIV, the virus that causes AIDS, increases the risk of tuberculosis.

Versions of the test are licensed in a number of European countries, Canada and Japan, but not in the United States, the teleconference speakers said.

Researchers have documented the test's accuracy in South Africa, where government officials are today expected to recommend its widespread use in that country.

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