The urgent need for new TB diagnostics

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The Global Center’s David Bryden is reporting from the 41st Union World Conference on Lung Health, this week in Berlin.

The recent article in The New Yorker by Michael Specter, “Letter from India: A Deadly Misdiagnosis,” is required reading for anyone interested in global health, drug resistance and expanding access to affordable tuberculosis services.  The problems it reveals, including the irresponsible use of serological testing for TB in India, have been much discussed here in Berlin at the Union World Conference on Lung Health

TB kills about 900 people per day in India, or about two people every three minutes. And each year there are 99,000 cases of multi-drug resistant TB. Nearly five percent of the incident cases there are HIV-positive.

The article shows the web of financial incentives that lead physicians and small scale private sector providers to offer a blood test for tuberculosis which in fact provides no useful information and yet which costs patients, who are mainly poor, an enormous amount of money. 

In an online chat Thursday, Specter was asked, “Were any of the unlicensed doctors or shops [providing this test] reluctant to let you in? Are they at all nervous about getting caught?”  He replied, “Not one was reluctant or nervous. That is because it is so common there is no sense of doing anything wrong.”

When asked whether he felt optimistic about the situation in India or if the built-in incentives for private clinics to make money were just too substantial, Specter replied, “Well, it is going to be a tough challenge. But there are a lot of people out there trying to get these [state-of-the-art] kinds of diagnostics to those who need them – and the Indian government is filled with people who care. Also, the cost savings of using tests that are accurate would be immense over the long run.”

At a presentation yesterday in Berlin, the World Health Organization’s (WHO) Dr. Karin Weyer said that the WHO convened a group of experts to look at the use of serological testing for TB as well as the use of interferon gamma release assays.  Based on the results of that meeting, Weyer said in early 2011 the WHO will be issuing a strongly negative recommendation against both tests.  Experts from the Stop TB Partnership told me they hope this will help stamp out the widespread use of the serological test in India and other countries.

India has embarked on an ambitious program of upgrading and expanding the number of medical laboratories that can do proper TB testing, using microscopy, cultures, and line probe assay.  Yesterday at the Berlin meeting, the WHO’s Dr. Puneet Dewan said that India had set new targets as a part of its Revised National TB Control Plan, including early detection of 90 percent of all TB cases by 2015.  To do this, India is increasing the number of labs, increasing their capacity, and refining procedures.  He said that the country is drawing on some external funding for this expansion, including U.S. Agency for International Development support through PATH, and the WHO, UNITAID, and a Round 9 Grant from the Global Fund to Fight AIDS, TB and Malaria. Dewan said a crucial part of the strategy is the rapid adoption of new technology.

A new test with tremendous potential, discussed in The New Yorker piece, is the accurate and highly sensitive GeneXpert machine, which can diagnose TB in a sputum sample, including drug resistant TB, in just two hours.  The Xpert tests for presence of the bacterium’s DNA, and is currently the subject of intense negotiations between the manufacturer – Cepheid – and the Foundation for Innovative New Diagnostics (FIND) regarding how best to expand access at affordable prices.  Scientists are also investigating whether the machine could also be used to find TB using a stool or blood sample, which would make it very useful for pediatric diagnosis and for diagnosing TB outside the lungs.

Click here to see John Donnelly’s post on the subject of the GeneXpert and potential TB diagnostic breakthroughs with FIND’s CEO Georgio Roscigno.

The smallest version of the machine, which takes four cartridges for sputum samples, costs approximately $20,000 to $30,000, and the individual cartridges will sell for $20 to $30.  The Treatment Action Campaign in South Africa, joined by nearly 50 other groups from around the world, are delivering a letter this week to John L. Bishop, CEO of Cepheid,  to urge the company to take steps to make the machine and the cartridges more affordable, as well as ensure access to ongoing training  and required maintenance procedures.  One of the signers is the noted physician, Dr. Francois Venter, on behalf of the Southern African HIV Clinicians Society.

One thought on “The urgent need for new TB diagnostics

  1. rog

    I was surprised to read that WHO are to release a negative recommendation on
    the use of interferon gamma release assays.

    Interferon gamma release assays have been approved in the USA, Japan, EU and are in widespread use across the globe.

    The US CDC has issued guidelines indicating their preference for interferon gamma release assays in particular circumstances.

    WHO have published a study on serological tests for TB, it is available here.


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