A test that can detect TB, including drug-resistant forms, in less than two hours could revolutionise treatment of the disease, according to the World Health Organisation, which is urging its roll-out across the globe.
Tuberculosis killed 4,700 people every day last year. The annual death toll of 1.7 million includes 380,000 people who are at particular risk because they have HIV, the virus that depresses the immune system and causes Aids.
The current diagnostic test for TB has been used for 125 years. It involves microscopic examination of a sputum sample and is not ideal because it doesn’t easily detect the growing number of strains that are resistant to antibiotics, or TB where the patient is also infected with HIV.
Some patients have to wait as long as three months to be diagnosed, which means their treatment is delayed and their prospects of recovery are reduced. The long wait also increases the chances they will infect others and, if they are given the wrong antibiotics for their particular strain of TB, drug resistance can worsen.
The new test delivers a result in 100 minutes. Dr. Mario Raviglione, Director of the WHO’s Stop TB department, said, “This new test represents a milestone for global TB diagnosis and care. It also represents new hope for the millions of people who are at the highest risk of TB and drug-resistant disease.”
He added, “We have the scientific evidence, we have defined the policy, and now we aim to support implementation for impact in countries.” The number of TB cases is set to rise as the test is rolled out. The WHO says drug-resistant cases could increase threefold and the number of cases where the patient is co-infected with HIV could double.
Trials and demonstration studies have been carried out over 18 months in a number of different countries, involving more than 8,000 patients. The test is a fully-automated nucleic acid amplification test, which the WHO says is simple and safe to use. It incorporates modern DNA technology that can be used outside of conventional laboratories - although the need for a constant electricity supply may be a problem in rural settings.
The major issue will now be cost. The market price for the equipment is $55,000 to $62,000, with an additional $55 to $82 for the cartridges it uses. The makers, Cepheid, have agreed to cut the price by 75 per cent for the poorest countries. However, at $16.86 per test, the cost is higher than the current system and the roll-out will depend on donor funding.
http://www.thehindu.com/health/medicine-and-research/article941615.ece
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