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Accurate diagnosis – imperative for TB control in India

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The figures are out there.  There is enough evidence to show India has a serious TB problem on hand and it’s undeniably a cause for concern.  To use a cliche’, while prevention is the best form of cure, it is still aeons away in India, as we have a myriad problems to solve before that.  Where are we on nutrition, sanitation, housing, poverty alleviation, etc, etc?  That’s another story, but it’s also very closely linked to TB control, mainly prevention and one cannot be achieved without the other.

Given that we will continue to have people spreading TB and continue to have people falling ill with TB till the basic issues are fixed, isn’t it logical that we need to put robust diagnostics and treatment regimens in place if we want to prevent the problem from getting worse that it already is? TB is easily cured if accurately detected and treated on time, but this is currently a big challenge in India and the causes for this are many.

Diagnosis for instance.  The most widely used method of TB diagnosis (sputum smear microscopy) currently used, misses more than half of all cases and is largely ineffective in patients with HIV co-infection; while the most sensitive test (culture testing) takes weeks to provide a result, is costly and can only be carried out by highly-trained staff in specialist laboratories.  Additionally, as the first blog on this site demonstrated, the sputum test cannot be used for children as they are unable to cough up sputum unlike adults.

Ineffective TB diagnostics are a lucrative market in India. Patients seeking TB care in the private sector are commonly subjected to diagnostic tests i.e. the antibody-based blood tests, including ELISA, that are completely ineffective at detecting TB. This is because a large number of the world’s population has TB antibodies (which will show up in the blood test), though only about 10% of them will go on to develop the active form of the disease. If patients who do not have TB are misdiagnosed, they could undergo six months of toxic treatment. If patients have active TB and the test misses it, the disease may worsen and they may continue to spread the disease in their community.

According to a preliminary analysis of over 80 labs in the country, it is estimated that patients undergo more than 1.5 million useless TB antibody tests each year. “If they worked, the problem of a gap in the pipeline for a point-of-care assay would have
been solved decades ago,” comments Madhukar Pai, co-chair of the STOP-TB
Partnership’s new diagnostics working group. “The pity is that they don’t work.
In fact, they’re inaccurate and useless. If they worked, the problem of a gap in the pipeline for a point-of-care assay would have been solved decades ago”, comments
Madhukar Pai, co-chair of the STOP-TB Partnership’s new diagnostics working
group. (WHO recommends against innacurate tuberculosis tests by Kelly Morris, Vol 377 January 8, 2011)

The absence of regulatory mechanisms results in the import of these inaccurate diagnostics from France, the UK, US or other countries, where these tests are not approved for TB diagnosis. These tests generate at least US $15 million. In a country that has around 100,000 labs, this estimate is probably only a fraction of the total market.

Correct diagnosis is crucial to the control of tuberculosis in India, particularly in view of the fact that India has set new targets as a part of its Revised National TB Control Plan (RNTCP), which includes early detection of 90 percent of all TB cases by 2015.

Bharathi Ghanashyam

For further reading:WHO recommends against inaccurate tuberculosis tests

Written by JournalistsAgainstTB

January 11, 2011 at 3:04 pm

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