The World Health Organization (WHO) said that a new test that can detect tuberculosis (TB), including drug-resistant forms, in less than two hours could revolutionize treatment of the disease. Tuberculosis is still a major killer worldwide killing 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.
At present the test that diagnoses the disease is 125 years old and it means microscopic examination of a sputum sample. It fails to be accurate and does not detect the growing number of strains that are resistant to antibiotics, or TB where the patient is co-infected with HIV. At places this takes as long as three months to be diagnosed. This means their treatment is delayed and their recovery prospects decreased. This gap in time 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 gives results in 100 minutes said Dr Mario Raviglione, director of WHO’s Stop TB department. He added, “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… We have the scientific evidence, we have defined the policy, and now we aim to support implementation for impact in countries.” The number of resistant cases could increase threefold and the number of cases where the patient is co-infected with HIV could double once the actual figures come out via this test. A study published in the New England Journal of Medicine in September showed the test, called Xpert MTB/RIF, is 98% successful in identifying TB in more than 1,700 people.
The new test has been tried for over 18 months in a number of different countries, involving more than 8,000 patients. It is an automated test based on the principle of 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. On the other hand it needs continuous electricity supply – a problem in many rural areas.
It has been developed by 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. It will cost $55,000 to $62,000 (£35,000 to £39,000), with an additional $55 to $82 for the cartridges it uses. This may become a hurdle but makers, Cepheid, have agreed to cut the price by 75% for the poorest, worst-affected countries. 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 that may come from US government’s Pepfar and the Global Fund to fight Aids, TB and malaria. The test is slated to start in South Africa and India.
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