In December 2012, Dr Zarir Udwadia and team published a report about 12 totally drug resistant (TDR) TB cases. It blew up into a controversy with the Union Ministry later deciding that it was to be called XXDR-TB (extensively drug resistant TB). Today there is some good news that some of those patients have tested negative after salvage treatment. In hindsight, was the controversy a wake up call – for policy makers as well as treating clinicians?
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Dr Camilla Rodrigues
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In any eventuality, whatever helps patients is good. Yes the controversy did help drug resistant patients in Mumbai.
What are the trends in TB diagnostics in India?
Lack of diagnostics for TB has been a a crucial barrier in the past. Smear microscopy is rapid and cost effective but requires a sufficient number of TB bacilli to flag as positive. Much reliance was placed on chest X-ray but now India’s Revised National TB Control Programme: (RNTCP) has moved away from that.
In the last five years, the WHO has given a boost to validating TB diagnostics.
For one, the WHO has issued a negative policy recommendation on the use of serology that was being used rampantly in our country. We live in a TB endemic country and most of us are TB IgG positive. A positive serological test was used as a valid reason to prescribe TB drugs for any suspicious lesion on the lung or any patient who had a pyrexia of unknown origin.
The Government of India issued a Gazette notification in mid-2012 which banned the use of serology tests. The Government is vital in such situations because they have the wherewithal to stop the import of such kits. This has been a great step towards getting on the right track to diagnose TB.
Secondly, there is another test known as the interferon gamma release assay This is a good test to diagnose latent TB. But again, most Indians are latently infected with TB. The problem with this test is that it can detect latent TB but cannot differentiate it from active TB. WHO has come out with a negative policy recommendation, for the use of these tests in the diagnosis of active TB in endemic countries
In 2010, WHO advocated the use of GeneXpert MTB/RIF assay for MDR suspects. This molecular test diagnoses TB as well as accurately detects drug-resistance to rifampicin. The test takes two hours to give results and does not require any skilled manpower and is a game changer in TB diagnostics.
Currently in India, the cost of consumables for Xpert is being subsidised by the Foundation of Innovative New Diagnostics (FIND), in the public sector, as well as in the private sector via the Initiative for Promoting and Affordable Quality TB Tests (IPAQT). All accredited labs can become a part of IPAQT. Under this initiative, in the private sector, the effective reduction in cartridge cost is passed on to the consumer.
Two additional tests that WHO has approved are:
- MGIT automated liquid culture which allows for much faster detection of TB Liquid culture clearly enhances the rate of recovery and the time to detection. To have a TB culture facility, you require biosafety precautions in place. Expertise is required to avoid contamination issues .
- Another molecular test that is called the Hain Line Probe Assay (LPA). The National Programme is training personnel across the country to do these tests. These tests, in the last five years, have completely revolutionised TB diagnosis. In fact, sometimes at a molecular level, TB is detected faster than other routine infections!
We now require non-invasive, point-of-care tests, but we are at least two years away from such immuno-chromatic tests (ICTs) for detection of TB.
What has been the response of policy makers in India and the RNTCP?
Laboratory capacity building for TB in the nation will take time. I think the response of the programme has been good because you have public hospitals like JJ Hospital in Mumbai that also perform the LPA tests. The authorities have outlined certain areas in each state for upgradation.
Where are the gaps?
The gaps exist in terms of improving patient awareness about these tests and their availability. Patients still want a blood test done rather than a test based on sputum. To convince patients that these tests are actually better than a blood test needs a lot of awareness.
It is also important to create awareness about the fact that a cough persisting for over two weeks, weight loss, night sweats, low grade fever cannot be ignored and require a consultation. If the person has had TB before, or is in contact with a person with drug resistant TB, then we need to quickly do a test to diagnose resistance. And the earlier testing is done, unnecessary treatment can be avoided. If required, treatment too has to be rational. So, physicians need to be goaded into that direction. The situation is definitely improving. Role models, perhaps from Bollywood, may help to raise awareness about such issues!
One of the projects you are working on is testing biomarkers for immunity to Mycobaterium tuberculosis in exposed but uninfected healthcare workers, which is a collaborative project with Imperial College, London, UK. Could you tell us a little about this project?
This project is looking at why some healthcare workers, like nurses, paramedics etc., who though being continuously exposed to TB are not positive for latent TB. We are looking at biomarkers in their immune system that prevents the normal response. We are doing this in collaboration with Dr Ajit Lalwani in Oxford.
A lot of imaging techniques are been investigated to diagnose TB in cases like bone TB. What are you views on that?
To be very honest, from a microbiology perspective, seeing is believing. I have to see the micro-organism. So, I do not think we can make judgement calls based on radiological examination alone. We need to have a sample from the patient and test it.
The 16th Annual L’Oréal-UNESCO for Women in Science Awards awarded five women scientists on International Women’s Day. Do you feel that women scientists in India get their due? What can be done to set this right?
They need better visibility within the scientific community. I also really believe in the power of the pen. If you publish good work, you get noticed.
What is the future of microbiology?
The sky is the limit as far as microbiology is concerned because everything starts with a diagnosis. There is so much that can be done and you need passionate and motivated people