Automated Plasmodium detection by the Sysmex XN hematology analyzer

Malaria is a potentially severe disease affecting nearly 200 million people per year. Early detection of the parasite even in unsuspected patients remains the challenging aim for effective patient care. Automated complete blood counts that are usually performed for any febrile patient might represent a tool to ascertain malaria infection.

To evaluate the ability of the new generation of the Sysmex hematology analyzer (XN-series) to detect malaria.

We retrospectively studied 100 blood samples performed with the recent Sysmex XN analyzer that were positive for Plasmodium and explored its ability to detect the parasite. 100 samples from patients uninfected by malaria were used as control group.

Specific abnormalities such as additional events in the mature neutrophil/eosinophil area of the white blood cells differential (WDF) scattergram were noted for 1.1% of Plasmodium falciparum samples and 56.2% of other Plasmodium species samples. Mature parasite stages (schizonts or gametocytes) were observed on blood smears among those samples. WDF scattergrams were able to detect 80.0% (12/15) of Plasmodium mature stages. Furthermore, the differential in white blood counts between WDF and white cell nucleated (WNR) channels was a predictive signal of Plasmodium mature stages in 73.3% (11/15) of samples and may be explained by a differential destruction of particles with the analyzer reagent.

Associated to thrombocytopaenia, a Sysmex XN Plasmodium pattern may represent a useful warning for Plasmodium detection in unsuspected patients, particularly when mature parasite stages are present.