Are molecular tests accurate enough to diagnose sleeping sickness?

Recently the department Biomedical Research of the Royal Tropical Institute (KIT) investigated the accuracy of new, high-technology diagnostics for sleeping sickness.

There were two leading questions. Firstly, does the accuracy of these tests warrant their implementation in endemic settings. Secondly, should limited resources be re-directed towards this goal.

Results
KIT Biomedical Research found that polymerase chain reaction (PCR) tests seem to have an acceptably high specificity and sensitivity for diagnosis of stage I sleeping sickness.
This conclusion is based on multiple-microscopy based techniques as reference standards (which may have low sensitivity) and a patient population that was not always representative.  

DNA amplification techniques can now help diagnose patients with many diseases, both communicable and non-communicable. A range of amplification techniques has been developed for the diagnosis of human African trypanosomiasis (HAT) with PCR at the forefront. Even though this is a high-technology diagnostic we expect the applicability of these tests to increase as laboratory strengthening in endemic areas increases. However, careful evaluation of these tests against the current reference standard, microscopy, must precede implementation. In addition, we must know whether to direct the limited resources available for sleeping sickness towards implementing molecular diagnostics in endemic areas. All published data on molecular amplification tests for sleeping sickness were pooled to see if we could make a generalised statement about the accuracy of these tests.

Recommendations
Based on our findings, it is apparent that there is not enough accuracy data to replace microscopy or serology for diagnosing sleeping sickness. We recommend that future studies should include those patients for which PCR may become the test of choice in order to ensure the diagnostic accuracy data available is representative for endemic populations. More certainty about the practical value of PCR tests for HAT diagnosis should come from non-accuracy design studies, like feasibility or cost-effectiveness studies.

You can find the publication here.

• Tags
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• diagnostics |
• disease control |
• health |
• health systems |
• research |
• trypanosomiasis

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