New test quickly detects multi drug-resistant tuberculosis

Jul 1 2008

Researchers have developed a new test which can quickly detect multi drug-resistant tuberculosis (MDR-TB).

The DNA-based test is a breakthrough in diagnosing MDR-TB and takes just two days to show results.

According to the World Health Organisation (WHO) the rapid molecular diagnostic tool will be available over the next four years in sixteen countries.

At present the standard tests take up to three months because only 2 percent of MDR-TB cases worldwide are diagnosed and treated appropriately.

The new test will mean diagnosis and treatment of MDR-TB can be expected to increase to 15 percent or more within four years.

The WHO says the test only costs $5 but another $15 then has to be spent on lab equipment and staff salaries, taking the total cost to $20 compared with up to $34 for older methods.

The new test can detect, directly from a patient's saliva, whether the tuberculosis bacteria can be treated with the two main antibiotics, isoniazid and rifampicin, making it easier to prescribe the drug to cure the disease and prevent its spread.

Previous tests required saliva samples to be incubated for as many as 60 days in order for microbacteria to grow and be tested against different antibiotic compounds.

Drug-resistant tuberculosis strains are particularly dangerous for HIV/AIDS sufferers and those with weak immune systems and errors in prescribing antibiotics can worsen drug resistance problems and lead to XDR-TB.

XDR-TB an untreatable form of the disease that has emerged in 49 countries including the United States, France, Russia, South Africa, Brazil and Australia.

Lesotho will be the first country to receive the lab equipment and training to use the new diagnostics under a programme supported by the WHO's partners UNITAID and the Foundation for Innovative New Diagnostics.

Other countries due to receive support to use the new test in the next four years are: Azerbaijan, Bangladesh, Cote d'Ivoire, the Democratic Republic of Congo, Ethiopia, Georgia, Indonesia, Kazakhstan, Kyrgyzstan, Lesotho, Moldova, Myanmar, Tajikistan, Ukraine, Uzbekistan and Vietnam.

The tests are currently only used in research settings, but soon 16 countries with a significant MDR-TB problem will become equipped to use the test.

The United Nation estimates 400,000 new cases of MDR-TB out of 9 million TB cases will occur every year.

The problem at present lies in the usually late detection of the infection when no response to standard TB treatment is likely and this delays the administration of second-line drugs - late detection makes MDR-TB harder to treat and the new test which is affordable, promises to be both feasible and effective in countries where TB is endemic.

Mario Raviglione, director of the WHO's Stop TB department, says the molecular test represents a big breakthrough in the fight against tuberculosis, a contagious respiratory ailment that kills 1.5 million people a year.