TB: Centre bans ‘inaccurate’ serology tests

The Centre has banned the manufacture and sale of serodiagnostic kits for tuberculosis. A notification issued by the Joint Secretary

Written by Anuradha Mascarenhas | Pune | Published:June 20, 2012 12:46 am

The Centre has banned the manufacture and sale of serodiagnostic kits for tuberculosis. A notification issued by the Joint Secretary,Ministry of Health and Family Welfare,Arun Panda on June 7 states that serodiagnostic test kits have led to imprecise results and inconsistent diagnosis of TB,leading to risk to human lives.

According to Section 26(A) of the Drugs and Cosmetic Act,1940,the Centre has prohibited the manufacture,sale and distribution of the serodiagnostic test kits for diagnosis of tuberculosis.

The Indian Express had in August last year reported that scientists had warned against the use of TB tests as they were inaccurate.

Dr Madhukar Pai,Associate Professor at McGill University,Canada,and Dr Karen Steingart of the University of Washington School of Public Health,Seattle,had performed a systematic review and meta-analysis of 92 studies evaluating the diagnostic accuracy of commercial serological tests for pulmonary and extra-pulmonary TB (where the infection affects parts of the body other than the lungs) with focus on their relevance in developing nations.

They concluded that the accuracy of serological tests is very low for both forms of TB.

When contacted,Pai said,“To my knowledge,India is the first and only country to have banned these tests,following the WHO policy. Hopefully,the ban will be enforced and patients in the private sector will now be protected from a useless test.”

According to Dr Sarman Singh,Professor of Clinical Microbiology at the All India Institute of Medical Sciences (AIIMS),Delhi,poor detection rates lead to mismanagement of infectious cases and possibility of drug resistance development. Singh and Dr V M Katoch,Director General of Indian Council of Medical Research have in their recent paper in the Indian Journal of Medical Research pointed out that a search showed there were more than 73 manufactures of TB serological test kits.

Most of these (60) are prepared in rapid test format as compared to microwell ELISA (13). Sensitivity or ability to diagnose true TB cases is very critical and any test which has lesser detection rate than sputum microscopy does not warrant serious attention.

India accounts for one-fifth of the global TB burden — 9.2 million new cases and 1.7 million deaths every year.

It is estimated that due to high false positivity of commercially available serological tests,1,57,000 false (non-diseased) cases may be wrongly treated in India alone.

This costs billions of rupees to the government and thousands of such wrongly treated cases may develop side effects of anti-TB treatment,says Singh.

How it can be diagnosed

* Tuberculosis can be diagnosed through chest X-rays,analysis of sputum,skin tests. Chest X-rays can reveal evidence of active tuberculosis pneumonia. X-rays can also show scarring (fibrosis) or hardening (calcification) in the lungs,suggesting that the TB is contained.

* Examination of the sputum on a slide (smear) under the microscope can show the presence of TB-like bacteria. A sample of sputum is usually taken and cultured in special incubators so that the TB bacteria can be identified.

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