NextBillion - An Initiative of the William Davidson Institute at the University of Michigan

Wednesday, October 30, 2013

London — A new, sophisticated diagnostic test for tuberculosis now being rolled out promises to be faster and more accurate than the old methods and much easier to use. But the first trials of the GeneXpert MTB/RIF Assay test in real-life situations have proved that while all this is true, it did not make any significant difference to treatment outcomes.

The problem with the traditional TB tests is that they need trained lab technicians and tend to be either inconclusive or extremely slow. Some cases of TB can be spotted simply by inspecting a sputum sample under a microscope, but not all; chest X-rays can also be a guide as to whether the disease may be present.

But to be sure, the samples have to be cultured in a laboratory, and the process takes around eight weeks to produce a result. By then a patient may have wandered off and disappeared, and even if he does then start treatment, he has had two more months to infect other people.