Rapid tests for drug-resistant TB

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 due to two initiatives 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 should increase that proportion at least seven-fold over the next four years, to 15% or more.

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

Over the next four years — as laboratory staff are trained, laboratory facilities enhanced and 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 2009-11 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.