Blood test to detect TB is unreliable: WHO

Updated on: Aug 8, 2011, 23:54:36 IST

Hindustan Times | By Chetan Chauhan, New Delhi

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The World Health Organisation (WHO) has termed the commonly used methodology to detect tuberculosis (TB) as unreliable with Indian health ministry deciding to issue an advisory to hospitals to discontinue popular blood tests. Chetan Chauhan reports.

The World Health Organisation (WHO) has termed the commonly used methodology to detect tuberculosis (TB) as unreliable with Indian health ministry deciding to issue an advisory to hospitals to discontinue popular blood tests.

The blood tests are conducted on about two million people every year to detect tuberculosis, of which the WHO says about half of the results are wrong. Both private and government hospitals in India use blood tests to detect TB.

"They are a waste of time, and they are a waste of money, and very importantly, they put at risk those people who suffer from TB," Mario Raviglione, director of WHO's Stop TB department said, while releasing a negative policy recommendation for the tests.

This comes after the WHO started investigating the blood tests in 2005 after governments reported increase in prevalence of TB despite machinery to provide medical aid to the patients.

“The tests may have failed to detect TB and by the time it got detected it was too late,” said a senior health ministry official.

After a six year long analysis, the WHO termed the tests as a money making business centered on selling substandard tests on unreliable results. The WHO also found that some companies had remarketed the tests under different names after the earlier versions were found to be giving imperfect results.

The doctors were also getting financial incentives to conduct the test based on detection of antigens produced by Mycobacterium tuberculosis, the organism that causes TB.

The WHO also warned that consequences of such inaccurate diagnoses were significant as TB goes untreated and individuals are not only at risk of death but also unknowingly transmit the disease to others.

“Antibody response is a poor indicator because the various types of mycobacteria share antigens, and other infections raise similar antibody responses,” said a report published in Science Magazine this week.

In place of blood tests, the WHO has recommended use of standard microscopy or a new molecular testing system called GeneXpert.

“The advantage of GeneXpert is that you can immediately diagnose TB and determine whether that TB is drug resistant or not,” the WHO said.

The new test provides results in two hours compared with the weeks required to complete a traditional TB culture diagnosis. However, the testing equipment costs US $ 20,000.

Although Health ministry has not suggested any alternative it wants medical associations across India to look for affordable alternatives in wake of the WHO finds.

ABOUT THE AUTHOR
Chetan Chauhan
Chetan Chauhan is the National Affairs Editor looking into all aspects of news and features from across India. A Chevening scholar with over three decades of experience in reporting and news management, Chetan has extensively covered all important aspects of the social sector, political economy, environment and climate change nationally and internationally. He did a journalism course at the Reuters Institute of Journalism in Oxford and Digital Media training at Nanyang Technological University in Singapore. He started as a reporter with The Statesman in 1996 and joined the Hindustan Times in 2000 in the metro bureau covering environment, crime and Delhi politics. He covered hot local news, from the Jessica Lal murder case to the rebellion of Delhi Congress MLAs against then Chief Minister Sheila Dikshit, to the replacement of toxic vehicle fuel with cleaner compressed natural gas (CNG) in the national capital. Some of his stories on air pollution became part of the Supreme Court’s landmark MC Mehta versus Government of India case in the National Capital Region (NCR), forcing the government to take corrective measures. As part of the national political bureau since 2004, he covered important central sectors such as environment, education, social justice, labour, rural development, water resources, renewable energy, agriculture, broadcasting and the Planning Commission for more than a decade producing several exclusive and investigative breaking stories. His specialisation is the environment, having covered at least a dozen United Nations global conferences on climate change, biodiversity and wildlife including climate summits in Paris, Copenhagen and Bali. He also covered India’s two five-year plans ---11th and 12th and reported on drafting and execution of right based laws such as Right to Education, Right to Information and rural job guarantee law, MG-NREGA, now being introduced in new format as VG-RAM-G Act. He has in-depth knowledge of social sector issues. He was one of the first to report on tigers vanishing from Sariska and Panna wildlife reserves in 2004 and 2008, respectively, leading to the setting up of the National Tiger Conservation Authority (NTCA) and the introduction of stringent penal provisions for poaching. He has written extensively on the rising human-animal conflict in India and the degradation of India’s biodiversity hotspots because of mining and other activities. Since 2004, Chetan has covered Parliament comprehensively and participated in training on the nuanced coverage of Parliament proceedings. He has travelled extensively across India to cover national and provincial elections since 1998, especially in the Hindi heartland states, considered India’s road to power. He writes a regular column for Hindustan Times, Ecostani, on important national politics, economy, Himalayan ecology and environmental issues. His other responsibilities include providing inputs for edits and edit page articles for the publication, apart from managing news flow from across India.Read More

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