Laboratory diagnosis of malaria by conventional peripheral
blood smear examination with Quantitative Buffy Coat
(QBC) and Rapid Diagnostic Tests (RDT) - A comparative
study

Bhat S; hya K; Sastry Apurba S; Nagaraj E.R.; Sharadadevi Mannur; Sastry An; S

Abstract

Laboratory diagnosis of malaria by conventional peripheral blood smear examination with Quantitative Buffy Coat (QBC) and Rapid Diagnostic Tests (RDT) - A comparative study

Aim: Rapid diagnosis is prerequisite for effective treatment and reducing mortality and morbidity of malaria. Microscopy has been the Gold standard for malaria diagnosis for decades. Recently, many new rapid diagnostic tests like Quantitative Buffy Coat (QBC) examination and rapid antigen detection methods are being widely used. We made an attempt to compare peripheral smear, QBC and rapid antigen detection methods for the diagnosis of malaria.

Materials and Methods: A total number of 500 samples were collected from patients presenting with classical symptoms of malaria. Thick and thin blood smears were prepared and stained with Leishman’s stain. QBC, Histidine Rich Protein-II antigen test and plasmodium Lactate Dehydrogenase tests were done using commercially available kits.

Results: Taking thick smear as gold standard, thin smear had sensitivity, specificity, positive and negative predictive values of 90.9%, 100%, 100% and 98.6% respectively. QBC showed sensitivity, specificity, positive and negative predictive values of 95.45%, 100%, 100% and 99.31% respectively. HRP-II antigen detection showed sensitivity, specificity, positive and negative predictive values of 56.06%, 100%, 100% and 94.20%. pLDH showed sensitivity, specificity, PPV and NPV of 95.45%, 100%, 100% and 99.40% respectively.

Conclusion: In our study, QBC had highest sensitivity followed by pLDH assay. Leishman’s stained thick smear is cost effective but requires technical expertise to interpret the results, so if facilities are available, QBC can be used for routine diagnosis. In places where facilities are not available rapid diagnostic test devices can be used, especially in endemic areas.

Author(s): Bhat Sandhya K , Sastry Apurba S , Nagaraj E.R. , Sharadadevi Mannur , Sastry Anand S

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