Abnormal WBC scattergram: a clue to the diagnosis of malaria

Malaria is highly prevalent and endemic in tropical countries and carries a significant health burden. The detection of malaria by light microscopy of Giemsa-stained smears is the gold standard. There are many hematological abnormalities associated with malaria like anemia, thrombocytopenia, and leucopenia; however, none of these abnormalities are specific. The present study was undertaken to assess the utility of WBC scattergram in predicting the diagnosis of malaria.

In this study all cases diagnosed as Plasmodium vivax/Plasmodium falciparum infection on peripheral smear examination were included. Their complete blood counts and WBC scattergrams obtained from XT2000i were critically evaluated. Accordingly, sensitivity, specificity, positive predictive value (PPV), and negative predictive value of detection of malaria by abnormal WBC scattergram with and without abnormal blood counts were also calculated.

A total of 2251 ethylendiaminetetraacetic acid samples were run on XT2000i hematology autoanalyzer. Out of these 148 cases of malaria were diagnosed on peripheral smear (128 P. vivax and 20 P. falciparum). While analyzing the WBC scattergrams, 233 cases including 124 (83.8%) malaria cases showed different abnormalities. Sensitivity and PPV for the diagnosis of malaria by abnormal WBC scattergram were 83.78 and 53.20%, respectively. This had increased to 98.60 and 57.25%, respectively, when cytopenias were included.

Sysmex XT-2000i is capable of detecting specific abnormalities in WBC scattergram in patients with malaria. Therefore, the presence of an abnormal WBC scattergram with thrombocytopenia in a febrile patient helps the pathologist to clinch the diagnosis of malaria.