21 Nov 2012
A faster method to test for tuberculosis has also proved more effective in a pilot project undertaken at 18 sites in the country.
The cartridge–based nucleic acid amplification test (CBNAAT), also called GeneXpert, has increased the detection rate at the 18 labs where it has been introduced, according to the results of a baseline survey. From World TB Day in March till October, 22,345 patients suspected with TB were tested with both CBNAAT and traditional procedures, with 20 per cent returning positive from the new method against 10–12 per cent from the century–old, sputum smear microscopy test.
"The utility of this new test is mainly that it has helped increase the detection of TB cases," Dr Neeraj Raizada, medical officer of Foundation for Innovative New Diagnostics (FIND), told The Indian Express.
Central TB division officials said FIND is a technical partner of the government in looking for ways to detect TB cases faster. FIND is a not–for–profit foundation recognised by the Swiss government as an "other international organisation". With offices in a number of countries including India, it has been working closely with local authorities on introducing new tools into existing systems. In Maharashtra, Dr Sharad Sabnis, director of the state TB control programme, said GenXpert tests has begun at Dharavi, Mumbai while those in Amravati will start soon.
The test’s other major advantage is that it reduces the diagnosis time from eight weeks to two hours for a drug–resistant TB patient, and treatment can start immediately.
The flip side is that GeneXpert detects cases that are strugling for treatment anyway. Dr Zareer Udwadia, chest physician at Mumbai’s Hinduja Hospital, agreed GeneXpert is a great device to identify drug–resistant TB cases, but questioned if India has the capacity to treat such huge numbers. Less than 1 per cent multi–drug resistant TB cases are being treated at government centres, he said, stressing the need to roll out better treatment strategies.
GeneXpert test for the presence of TB bacteria and resistance to the anti–TB drug rifampicin. The tool has WHO approval and the device can lead to a projected three times higher detection in drug–resistant TB.
The CBNAAT labs are part of Expand TB project, facilitated by FIND. The cost of a device is Rs 10 lakh and these have been funded by FIND.
According to programme officers, the technology will be made cost–effective so that it can be used in 100 districts. "The Xpert test is rapid and highly sensitive and now we will conduct further population studies to make it cost–effective," Raizada said.