Inaccurate tuberculosis test shows need for better diagnostics

Inaccurate TB tests are being sold across the developing world and are misdiagnosing millions of people.  Alarm is being raised over serology tests being sold by private companies.  These have been described by Madhukar Pai, co-chair of the STOP-TB Partnership’s diagnostics working group, as “inaccurate and useless”.  This problem highlights the desperate need for better regulation and an accurate and cheap point of care test for tuberculosis. 

Serodiagnostic kits claiming to diagnose TB are available in much of the developing world, but the problem is largest in India where there are over 2 million new cases of TB every year.  It is estimated that these kits are used on at least 1.5 million people in India with suspected TB each year.  These tests are not available from the national TB programme but are available through the unregulated private sector.  In many cases the tests give more false results than they do true ones, meaning people are either diagnosed for TB when they don’t have the disease or people who are suffering from TB are told that they are TB negative.

The problem is so great that the World Health Organisations (WHO) will make a negative policy recommendation early this year advising against the use of these tests.  This is the first such recommendation made by the WHO.  The tests are manufactured in many countries.  Although they are not licensed for use in western countries, they are still manufactured in countries like the UK, France and the US, as well as in India and China, and are sold primarily in the developing world.  The annual market in India alone is estimated to be around $15 million.

The demand for these inaccurate tests raises issues beyond the tragedy of people taking toxic TB drugs they don’t need or dying of TB after being diagnosed as not having the disease.  Clearly regulation needs to improve to stop the tests from reaching the market and consumers need to be educated about the risks of unregulated TB diagnostics.  Questions must also be asked about why people are seeking these diagnostic tests in the first place, suggesting that availability of accurate diagnosis needs to improve through the national TB programmes and costs need to be reduced.  Finally, it demonstrates the urgent need for an accurate and cheap point of care diagnostic TB test to be developed.

Governments and public health authorities must take action following the WHO’s negative policy recommendation to better regulate these tests, improve diagnosis through official channels and dedicate more resources towards developing accurate, cheap point of care diagnostic tests for TB.

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