Performance of Quantitative Buffy Coat, QBC Fluorescence and Staining Technologies™ Test, and SD Bioline™ Malaria Rapid Test in Malaria Diagnosis in Western Kenya

Abstract

Malaria remains the most important parasitic disease in sub-Saharan Africa as a cause of morbidity and mortality.  Effective management of malaria relies on prompt and accurate diagnosis to guide treatment.  The World Health Organization (WHO) recommends that all suspected malaria cases be tested before initiation of treatment, thus diagnosis of malaria requires parasitological confirmation of malaria parasites in the blood of suspected patients.  This cross-sectional study conducted at the Ahero County Hospital, Kisumu, Kenya, evaluated the performance of quantitative buffy coat (QBC) (QBC Fluorescence and Staining Technologies™(QBC F.A.S.T.™)-improved QBC system and SD Bioline™ malaria rapid tests) against 'gold standard' (Giemsa blood stained slides microscopy) for the detection of Plasmodium species in children<five years old (n=385)in a malaria holo-endemic area of western Kenya.  Real-time PCR was performed on discrepant samples across the tests and the gold standard (microscopy).Sensitivity of QBC, QBC F.A.S.T.™ and SD Bioline™ malaria rapid tests were 90% (95% CI: 85-94), 77% (95% CI: 71-83) and 91% (95% CI: 86-94), respectively, while specificity was 30% (95% CI: 24-37), 83% (95% CI: 77-88) and 67% (95% CI: 60-73), respectively.  The positive predictive values (PPV) were 58% (95% CI: 52-63), 83% (95% CI: 77-88) and 74% (95% CI: 63-80), respectively, while the negative predictive values (NPV) were 74% (95% CI: 63-84), 78% (95% CI: 71-83) and 87% (95% CI: 81-92), respectively.Although the standard QBC malaria test and the SD Bioline™ malaria rapid diagnostic test (RDT) showed better sensitivity relative to the improved QBC F.A.S.T.™ test, the latter had a better specificity.  The performance of these tests remains modest against microscopy.

Keywords: Malaria, Quantitative buffy coat, QBC F.A.S.T.™, SD Bioline™