Could GeneXpert viral load test represent a potential win-win for the TB and HIV responses?

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Researchers comparing measures in India study say yes

The breakthrough represented by the development and WHO approval in 2010 of the GeneXpert rapid test to detect tuberculosis and TB drug resistantance still stands alone among innovative diagnostic advances against the disease, researchers from McGill University writing to The Lancet Global Health journal have noted. But in contrast to the possibilities the test offered then, to increase TB case-finding by about 30 percent and to improve the effectiveness of treatment by identifying resistance to the most common treatments roughly three-fold, access to the tests continues to lag, stymied by cost and policies, even where they are needed most.

The authors of the correspondence in the August edition of the journal note that using the machine’s capacity to use different cartridges to test for additional diseases of global impact could maximize investments in the technology, as well as access to it. One of the most recent examples of that was reported here, with coverage of how the test had shown promise as a gold standard for monitoring the persistence of Ebola in survivors’ semen.

The authors point to another test enabled by Xpert technology, known for three years but still needing to be validated for clinical use in settings where it is needed, to provide quick, accurate measures of HIV viral load at the places where people being treated for the virus receive care. In India, they write, where in spite of accelerated acquisition of the technology, use of it to diagnose tuberculosis remains stalled, and where only an estimated 7000 of 800,000 needed HIV viral tests are completed, dual use of the tests could have a significant impact, both on tuberculosis detection and treatment, and on progress toward UNAIDS 90-90-90 goals for HIV treatment to be effective in at least 90 percent of people receiving it.

Comparing viral load measures provided by the current test used in India to results from GeneXpert in a hospital where Xpert technology already is in use for TB detection, they set out to show what the tests could do in a clinical setting. They encountered obstacles in both supply and quality of the cartridges, but they also found viral loads measured by Xpert and currently used technology close. The results are on par with those found in other countries they add. They note that in addition to the obstacles they identified in their research, price issues will need to be addressed.

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