Newer versus conventional methods in the diagnosis of malaria : A comparison

Abstract

Background: This study attempts to evaluate and compare the efficacy of polymerase chain reaction (PCR) and quantitative buffy coat (QBC) assay with conventional Giemsa stained peripheral blood smear (PBS) examination in the diagnosis of malaria. Methods: The study was conducted on 50 cases of smear positive malaria (group 1), 50 cases of clinically suspected malaria (group 2) and 15 healthy controls. All were subjected to Giemsa stain slide examination both thick and thin smear, QBC assay and PCR. PBS examination by Giemsa stain was taken as gold standard. Result: In this study the overall sensitivity and positive predictive value (PPV) of QBC assay in group 1 was 100% and that of PCR was 60% and 100% respectively. In group 2 the sensitivity, specificity, PPV and NPV of QBC assay was 100% and that of PCR was 71%, 100%, 100% and 73% respectively as compared to the gold standard. All the 15 healthy controls were negative by all the three assays showing 100% specificity. Conclusion: QBC assay was an excellent alternative to the conventional method as it is rapid and less time consuming and can directly demonstrate the parasite. Utility of PCR lies in species-specific diagnosis of falciparum malaria especially when there is a high degree of clinical suspicion and the report is negative by the other two methods.