Role of WBC Scattergram, Histogram and Platelet Indices in Diagnosis of Malaria

Introduction: Malaria, a parasitic disease affecting more than 300 million people every year can sometimes be most serious and fatal too. It continues to be a major global health issue. Detection of malaria by light microscopy is the gold standard, which requires time and an expertise. In endemic areas, it is impractical to manually screen all peripheral blood films for the parasite and poses a challenge to all the laboratories, especially when the parasitic index is low. A rapid and cost effective screening of malaria is possible with the automated analysers, which provides a hint and prevents the misdiagnosis. Aim: To study the changes in WBC Scattergram, Histogram and Platelet indices in Malaria cases and compare with normal individuals. Materials and Methods: Prospective study was done in which blood samples were analysed using Beckman coulter LH-780. The scattergram, histogram, platelet count, mean platelet volume, platelet distribution width and Plateletcrit (PCT) of both positive and negative cases were recorded. The abnormal scattergrams and additional peaks in WBC histograms along with platelet indices were compared with peripheral smear examination. Smears were made, stained with Leishman’s stain and examined. Statistical analysis was done by using software SPSS version 20. Fisher-exact test was applied to calculate the p-value and <0.05 was considered as significant. Results: Suspected malaria cases were 822, of which 74 (9%) cases were positive on peripheral smear examination. Abnormal WBC scattergrams were observed in 90.5% of cases with malaria. Abnormal WBC histogram peaks were noted in 97.2% cases. Of the haematological abnormalities studied, thrombocytopenia was seen in 94.5% of cases. Mean Platelet Volume (MPV) was normal in 83.7% of cases. PCT was reduced in all cases (100%). Platelet Distribution Width (PDW) was increased in 98.6% of cases. Conclusion: An abnormal scattergram, abnormal histogram along with thrombocytopenia, low PCT and increased PDW can predict presence of malaria. Although automated analysers are not a screening tool for evaluation of malaria, most of the laboratories in India have cell counters but awareness is lacking regarding specific patterns of malarial infection in the histogram and scattergram.