NAAT Revolutionizes TB Care and Control By Providing Accurate Diagnosis

One of the best chances of stemming the tide of tuberculosis (TB) epidemic in low and middle income countries is to thwart the transmission cycle by early diagnosis and treating it successfully without delay.

The microscope has been around since 1882 as the key standard TB diagnostic tool with low sensitivity (50-60%). It is clear that it is high time we use better, more effective and efficient tools to accurately detect TB.

This was a clear thought emerging out of the “International Symposium on Tuberculosis Diagnostics: Innovating to make an impact” (ITBS 2010), organized by the International Centre for Genetic Engineering and Biotechnology (ICGEB) in New Delhi, India with support from the Aeras Global TB Vaccine Foundation, Bill and Melinda Gates Foundation and Foundation for Innovative New Diagnostics (FIND).

Although high-income countries have moved on to using better and modern diagnostic tools, many low and middle income countries still rely principally on sputum smear microscopy.

One of the diagnostic tools that the World Health Organization (WHO) recently endorsed is a fully automated Nucleic Acid Amplification Test (NAAT) – Xpert MTB/RIF. This is a new and novel rapid test for TB which especially relevant in high TB burden countries.

According to WHO, the test could revolutionize TB care and control by providing an accurate diagnosis for many patients in about 100 minutes, compared to current tests that can take up to three months to have results. This WHO endorsement of NAAT has come after 18 months of rigorous assessment of its field effectiveness in the early diagnosis of TB, as well as multidrug-resistant TB (MDR-TB) and TB complicated by HIV infection, which are more difficult to diagnose.

But this new ‘while you wait’ test incorporates modern DNA technology that can be used outside of conventional laboratories. It also benefits from being fully automated and therefore easy and safe to use.

WHO is now calling for the fully automated NAAT to be rolled out under clearly defined conditions and as part of national plans for TB and MDR-TB care and control. Policy and operational guidance are also being issued based on findings from a series of expert reviews and a global consultation held last week in Geneva. The consultation was attended by more than a hundred representatives from national programmes, development aid agencies and international partners.

Affordability has been a key concern in the assessment process. Co-developer FIND (the Foundation for Innovative and New Diagnostics) announced recently it has negotiated with the manufacturer, Cepheid, a 75% reduction in the price for countries most affected by TB, compared to the current market price. Preferential pricing will be granted to 116 low and middle income countries where TB is endemic with additional reduction in price once there is significant volume of demand.

WHO is also releasing recommendations and guidance for countries to incorporate this test in their programmes. This includes testing protocols (or algorithms) to optimize the use and benefits of the new technology in those persons where it is needed most.

Though there have been major improvements in TB care and control, tuberculosis killed an estimated 1.7 million people in 2009 and 9.4 million people developed active TB last year. (CNS)