LONDON -A new rapid test for tuberculosis (TB) has received a major thumbs-up world Health Organization (wHO), a measure which should lead to deployment in the world in the coming years. The new test, in which a device the size of a luggage bag to air for bacterial DNA in a person's sputum is cheaper, faster and more accurate than standard TB tests used in developed and developing countries, representatives of WHO said yesterday at a press conference here.
"This system allows doctors to test the patient while the patient is sitting there [in the waiting room]", said Marieke van der Werf, director of research at the KNCV Foundation Tuberculosis in the Netherlands, a member a group that has examined the evidence for the accuracy of the test. the panel released its report in the New England Journal of Medicine in September.
the difference with tests existing is huge, said Van der Werf. most of the current tuberculosis screening methods are based on a centuries-old technique in which sputum samples were cultured for 4-6 weeks and then examined under a microscope for the presence of disease causing Mycobacterium tuberculosis . This long delay is particularly problematic for people who are immunocompromised and who can not wait for two months before going on treatment.
In 09, 9.4 million new cases of tuberculosis were recorded worldwide. TB can be treated with a course of 6 to 12 months to four different medications, but many patients in developing countries have no access to medicine or medical care too late. Untreated, the disease can be fatal. WHO estimates that there are about 1.7 million TB-related deaths each year worldwide.
New TB test was developed by Cepheid, a company in Sunnyvale, California, in partnership with the Foundation for Innovation New Diagnostics (FIND) and the University of Medicine and Dentistry New Jersey. It is a "fully automated" system, which even the health workers in developing countries can operate after minimal training, said FIND Chief Giorgio Roscigno.
At the press conference yesterday, FIND staff demonstrated the machine using a water sample. They put the liquid in a beaker and add a reagent, which would neutralize all the TB germs in the sputum infected by breaking their cell walls; then the sample was injected into a closed cartridge and jumped into the machine. The test, which takes only 0 minutes, would detect the TB bacteria by looking for genetic signatures characteristic, called PCR amplified in a process.
The test can also detect whether the microbes carrying a gene that confers resistance to rifampicin, a drug commonly used to treat tuberculosis. This is an important piece of information for doctors; if the patient is also resistant to a second drug called isoniazid it takes a separate test for know-strain is regarded as multi-drug resistant (MDR), and you have another cocktail of drugs to treat. WHO estimates that there were 440,000 new MDR-TB cases in 08. It also expects the new test to yield twice as tuberculosis diagnoses in people infected with HIV; about 12% of people with the disease are also HIV positive.
For non-governmental organizations and low- and middle-income, the cost per test is $ 16, a price should fall to $ 14 a year and $ 10 within 2 years . The machine costs $ 17,000; that is after a decline of 75% of the original price of Cepheid negotiated by FIND. The price is a fraction of what it would cost to build and staff a laboratory that performs standard microscopy test sputum smear, Roscigno said.
WHO convened a global meeting last week in Geneva to draw up plans on how the new test based on PCR can be made available as many countries around the world the quickly as possible. The agency has produced a roadmap that places 116 low- and middle-income first in line to receive cheap machines.
South Africa, India, Uganda and several other countries are considering deploying the test immediately. A crucial question is how it plays in the field, where tropical temperatures and the lack of electricity and Internet access - which the machine needs to signal that needs maintenance - could pose problems. A test version of the running machine on the batteries is already underway in India and Pakistan, among other countries, and the results are expected next year.
The new diagnostic tool raises new questions, however. Even if countries can detect MDR patients, most are not prepared to handle a large number of them, said Van der Werf. An effort led by WHO should be in place to get treatment to those in need, she said.
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