COMPARATIVE STUDY OF MODIFIED CENTRIFUGED BLOOD SMEAR, PERIPHERAL BLOOD SMEAR AND RAPID DIAGNOSTIC TEST METHODS IN THE DIAGNOSIS OF MALARIA INFECTION

Paul Columba Inyang-Etoh*, Godfrey Aniefiok Ben and Mfoniso Iniobong Udonkang.

ABSTRACT

The gold standard for malaria diagnosis is microscopy with peripheral blood smear (PBS). Rapid diagnostic test (RDT) is a substitute especially where trained personnels are not available. Adoption of methods which improve the accuracy of malaria diagnosis will reduce inappropriate use of new expensive antimalarial treatments. The aim of this study was to compare the modified centrifuged blood smear (MCBS) as an alternative and more sensitive technique in malaria diagnosis. Venous blood was collected from 140 symptomatic subjects and subjected to three techniques for the diagnosis of malaria; PBS examination, MCBS examination, and RDT (CareStart). The MCBS method detected infection in 40% of the subjects examined, followed by PBS (36%) and RDT (20%). MCBS had a sensitivity of 92% and specificity of 90%, while PBS recorded a sensitivity of 71.4%, specificity of 80%, PPV of 80% and NPV of 82%. RDT (CareStart) had a sensitivity of 43%, specificity of 95%, PPV of 85.7% and NPV of 91.4%. Addition of the centrifugation step in MCBS increased the sensitivity of the peripheral blood smear method from 71.2% to 92%, and also its specificity from 80% to 90%. This study has confirmed that MCBS is a more sensitive, easy to perform and affordable technique in the routine diagnosis of malaria.

Keywords: Malaria, Modified centrifuged blood smear, Peripheral blood smear, Rapid antigen detection.