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 (WHO), 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 far from ideal because it does not easily detect the growing number of strains that are resistant to antibiotics, or TB where the patient is co-infected with HIV.
Some patients have to wait as long as three months to be diagnosed, which means their treatment is delayed and their recovery prospects reduced. The long wait also increases the chances they will infect others and, if they are given the wrong antibiotics for the strain of TB they have, drug-resistance can worsen and spread.
The new test delivers a result in 100 minutes. Dr Mario Raviglione, director of 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 recorded TB cases is set to rise as the test is rolled out. 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 (NAAT), which WHO says is simple and safe to use. It incorporates modern DNA technology that can be used outside of conventional laboratories, says WHO – although the need for a constant electricity supply may be a problem in rural settings.
The test been developed by the Foundation for Innovative New Diagnostics (FIND) with the private company Cepheid and the University of Medicine and Dentistry of New Jersey. The funding came from the National Institutes of Health in the US and the Bill and Melinda Gates Foundation.
The major issue will now be cost. The market price for the equipment is $55,000 to $62,000 (£35,000 to £39,000), with an additional $55 to $82 for the cartridges it uses.
The makers, Cepheid, have agreed to cut the price by 75% for the poorest, worst-affected countries, and it will come down further as the test is more widely bought. However, at $16.86 per test, the cost is much higher than using the current system and extensive roll-out will depend on donor funding.
Donor organisations such as the US government's Pepfar and the Global Fund to fight Aids, TB and malaria have expressed an interest in helping. South Africa and India already have plans to introduce the test.