RESUMO
INTRODUCTION: Most studies dealing with automated hematology analyzers (HAs) and malaria diagnosis are conducted in endemic countries. METHODS: We retrospectively studied cell blood counts (CBCs) performed with Sysmex XE-2100 and XE-5000 HAs in our center (Angers, France) regarding 67 patients returning from endemic areas and infected with various Plasmodium species. RESULTS: In 83% of infected samples with Plasmodium vivax (Pv), ovale (Po), or malariae (Pm), extra clouds of dots were present in neutrophil and/or eosinophil area(s) on routine differential (DIFF) scattergrams. In contrast, samples infected with Plasmodium falciparum (Pf) failed to show such DIFF scattergrams, or any other suggesting malaria infection (0/ 49 pts). Abnormal areas from DIFF scattergrams were related to the presence of mature schizonts and gametocytes, undestroyed by lysis agent, the latter not observed in Pf-infected patients from our series. The internal parameter WBC[DIFF] - WBC[BASO] raised in parallel to parasitemia in Pv, Po, and Pm samples but could not be used as a surrogate for parasitemia. In Pf infection, reticulocyte/ immature reticulocyte fraction (IRF) ratio showed a significant correlation with parasitemia (P < 0.05). A diagnostic model developed for Pf in endemic countries showed sensitivity of 77%. CONCLUSION: Using SYSMEX analyzers, Pv, Po, and Pm infections are easy to ascertain as DIFF scattergrams are almost specific (specificity = 99.9%). Pf infection diagnosis by CBC may be a more promising tool.
