White blood cell differential fluorescence abnormal scattergram: A useful indicator for early detection of malarial parasite

Background & Objective: Undiagnosed malarial infectionis associated with significant mortality and morbidity. Laboratory investigations leading to rapid, accurate and timely diagnosis of malaria is still a challenge. This study was done to assess the utility of abnormal White blood cell differential fluorescence (WDF) scattergram for diagnosis of malaria. Our aim was to study the utility of WDF scattergram for early detection of malarial parasite.

Methods: All EDTA anti-coagulated blood samples received in laboratory during a period from Dec 2019 to May 2020 were analyzed on anautomated hematology analyzer, Sysmex XN 1000. All abnormal WDF scattergrams pertaining to plasmodium specie were critically evaluated and recorded. Review of Leishman-stained peripheral smears as well as immune-chromatographic assay by rapid test devices (RTD) was done. Accordingly, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for detection of malaria by abnormal scattergram were calculated.

Results: Out of total 1, 26,000of samples analyzed, abnormal WDF scattergrams were detected in 96 cases. Amongst these, 95.8% (92) were positive for MP on Leishman-stained peripheral smear as well as on ICT with a p-value of 0.05. WDF scattergram abnormalities typical of malaria showed a sensitivity of 80% and specificity of 93.26%. Positive predictive value of 95.8% whereas negative predictive value of 99.9% was detected. Significant findings of hemolysis, platelet clumps, nucleated RBCS (NRBCs) and RBC agglutination were noted in cases (n=4) with abnormal WDF scattergram negative for malaria on peripheral smear.

Conclusion: Interpretation of abnormal WDF scattergram not only increases the early detection rate for malarial parasite but isa strong indicator for presence of hemolysis, RBC agglutination, platelet clumps and leucoerythroblastic blood picture as well.