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New Test Can Rapidly Diagnose Multidrug-resistant Tuberculosis

By Liz Highleyman

Experts discussed multiple-drug-resistant tuberculosis at a news conference Monday in Geneva. Dr. Mario C. Raviglione, second from right, of the W.H.O., said a new test was “revolutionary.”

Tuberculosis (TB) is among the leading causes of death among people with HIV worldwide. In recent years, several countries have seen outbreaks of multidrug-resistant TB (MDR-TB) and even extensively drug-resistant TB (XDR-TB) in HIV patients.

On June 30, the World Health Organization (WHO), Stop TB Partnership, UNITAID (an international drug purchase facility), and the Foundation for Innovative New Diagnostics (FIND) announced that they would jointly distribute a new diagnostic test for MDR-TB that can quickly detect resistance to isoniazid and rifampicin, 2 of the antibiotics most often used to treat the disease. Experts estimate that about 5% of all TB cases worldwide are resistant to these drugs.

The new line probe assay, which detects resistance-associated mutations in TB genetic material (similar to how an HIV genotypic resistance test works) can produce results in 2 days, compared with the several weeks or months it can take to incubate and expose bacteria to various drugs (similar to how an HIV phenotype resistance test works).

More rapid identification of drug-resistant TB strains will reduced delays in establishing appropriate treatment, and in turn decrease transmission of resistant bacteria and emergence of further resistance due to inadequate treatment.

The test, produced by Hain Lifescience and Innogenetics, is ineffective for patients who cannot produce a sputum sample and cannot yet diagnose XDR-TB, though the company is working to develop a version of the test that will do so.

The new test is expected to cost less than the older standard assay. It will be distributed initially in Africa, then in several Central, South, and Southeast Asian countries over the next few years. In addition to the test, the Stop TB Partnership also plans to expand distribution of anti-TB drugs, in an effort to increase the percentage of MDR-TB cases that are properly diagnosed and treated from 2% to 15%.

Below is the text of the WHO's recent press release describing the new test:

New Rapid Tests for Drug-Resistant TB for Developing Countries

Geneva, 30 June 2008 -- People in low-resource countries who are ill with multidrug-resistant TB (MDR-TB) will get a faster diagnosis -- in two days, not the standard two to three months -- and appropriate treatment thanks to two new initiatives unveiled today by WHO, the Stop TB Partnership, UNITAID, and the Foundation for Innovative New Diagnostics (FIND).

MDR-TB is a form of TB that responds poorly to standard treatment because of resistance to the first-line drugs isoniazid and rifampicin. At present it is estimated that only 2% of MDR-TB cases worldwide are being diagnosed and treated appropriately, mainly because of inadequate laboratory services. The initiatives announced today should increase that proportion at least seven-fold over the next four years, to 15% or more.

"I am delighted that this initiative will improve both the technology needed to diagnose TB quickly, and increase the availability of drugs to treat highly resistant TB," said British Prime Minister Gordon Brown, who helped launch the Stop TB Partnership's Global Plan to Stop TB in 2006 and whose government is a founding member of UNITAID. "The UK is committed to stopping TB around the world, from our funding of TB prevention programmes in poor countries, to our support of cutting edge research to develop new drugs."

In developing countries most TB patients are tested for MDR-TB only after they fail to respond to standard treatments. Even then, it takes two months or more to confirm the diagnosis. Patients have to wait for the test results before they can receive life-saving second-line drugs. During this period, they can spread the multidrug-resistant disease to others. Often the patients die before results are known, especially if they are HIV-infected in addition to having MDR-TB.

The initiative comes just one week after WHO recommended "line probe assays" for rapid MDR-TB diagnosis worldwide. This policy change was driven by data from recent studies, including a large field trial -- conducted by FIND together with South Africa's Medical Research Council and National Health Laboratory Services -- which produced evidence for the reliability and feasibility of using line probe assays under routine conditions.

"Five months ago, WHO renewed its call to make MDR-TB an urgent public health priority," said WHO Director-General Dr Margaret Chan, "and today we have evidence to guide our response. Based on that evidence, we are launching these promising initiatives."

Two Projects

The new initiative consists of two projects. The first, made possible through US$ 26.1 million in funding from UNITAID, will introduce a molecular method to diagnose MDR-TB that until now was used exclusively in research settings. These rapid, new molecular tests, known as line probe assays, produce an answer in less than two days.

Over the next four years -- as lab staff are trained, lab facilities enhanced and new equipment delivered -- 16 countries will begin using rapid methods to diagnose MDR-TB, including the molecular tests. The countries will receive the tests through the Stop TB Partnership's Global Drug Facility, which provides countries with both drugs and diagnostic supplies.

As part of the project, WHO's Global Laboratory Initiative and FIND will help countries prepare for installation and use of the new rapid diagnostic tests, ensuring necessary technical standards for biosafety and the capacity to accurately perform DNA-based tests. One country, Lesotho, is already equipped to start using these tests; Ethiopia is expected to be ready by the end of 2008. The tests will be phased in during 2009-2011 in the remaining 14 countries.

Under a second, complementary agreement with UNITAID for US$ 33.7 million, the Global Drug Facility will boost the supply of drugs needed to treat MDR-TB in 54 countries, including those receiving the new diagnostic tests. This project is also expected to achieve price reductions of up to 20% for second-line anti-TB drugs by 2010. All the countries receiving this assistance have met WHO's technical standards for managing MDR-TB and already have treatment programmes in place. Some will use grants from the Global Fund against AIDS, Tuberculosis and Malaria to purchase the drugs.

"Through the US$ 60-million support provided by UNITAID, these projects are expected to produce significant results in diagnosing and treating patients as well as reducing drug prices and the costs of diagnosis. These efforts illustrate the way in which innovative financing can be deployed for health and development," said Philippe Douste-Blazy, Chairman of UNITAID's Executive Board.

7/08/08

Sources

World Health Organization. New rapid tests for drug-resistant TB for developing countries. Press release. June 30, 2008.

LK Altman. Officials Praise New Test for Drug-Resistant TB. New York Times. July 1, 2008.

 

 

 

 

 

 

 

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