The Correlation of Spurious Eosinophilia in Automated Hematological Analyzer Sysmex Xs-800i with Plasmodium Infection Diagnosis.

ABSTRACT

Context Automated analyzers based on flow cytometry have evolved as an effective adjuvant diagnostic tool in malaria diagnosis. Aim: To find out the correlation of interpretive (IP) message from automated hematology analyzer XS-800i and Plasmodium infection diagnosed in peripheral smear. Settings and Design: Prospective study carried over a period of 2 years (July 2010 to June 2012). Materials and Methods: All cases with IP message of eosinophilia in Sysmex XS-800i analyzer were screened for microscopic correlation of eosinophilia and other peripheral smear findings. Results: In 24 out of 5012 patients with eosinophilia, microscopic eosinophil counts were normal. In these 24 cases, IP message in hematology analyzers was that the eosinophilia and WBC scattergram showed narrowed space between the eosinophil and neutrophil population. On careful examination of the peripheral smears of all 5012 cases, 39 cases revealed different stages of Plasmodium vivax (trophozoites, schizonts or gametocytes) in erythrocytes. Conclusion: Peripheral smears of the cases having inconsistent eosinophilia result with that of Sysmex XS-800i analyzer should be examined carefully for the presence of malaria parasites in the red blood cells. Sysmex XS-800i analyzers have moderate range of sensitivity and high degree of specificity in diagnosing malaria as spurious eosinophilia.