Aims: An automated hematology analyzer XN-30 is a new flowcytometry-based device developed by Sysmex Corporation to quantitatively measure the number (MI-RBC#) and ratio (MI-RBC%) of erythrocytes which are infected with malaria parasites. It can also distinguish malaria parasite species by flagging “Malaria?(p.f)” or “Malaria?(others)”, and, in fact, in about a minute. In order to evaluate feasibility of the XN-30 for malaria diagnosis, we analyzed clinical blood samples.
Methods: The blood samples were collected several times from malaria patients who visited NCGM hospital. Plasmodium falciparum samples (22 patients), P. vivax samples (2 patients), P. malariae samples (1 patient), P. falciparum - P. ovale mixed samples (1 patient) and P. knowlesi samples (1 patient) were tested. The information obtained through the XN-30 measurement was compared with that obtained through microscopic observations.
Results: MI-RBC% was reported for all samples which were regarded as positive through microscopic observation. The correlation coefficient between the MI-RBC% and the parasitemia calculated by microscopy was 0.99. The XN-30 could also detect parasitemia as low as 50-100 parasites/μl. For the 22 falciparum malaria cases, "Malaria?(p.f)" was displayed for all the samples. For the 3 cases of non-falciparum malaria cases (2 cases of P. vivax, and 1 case of P. malariae), "Malaria?(others)" was displayed to all the samples from them. For a P. falciparum -P. ovale mixed infection and a P. knowlesi infection, "Malaria?(p.f)" was displayed for both of them, but we could suspect the presence of non-falciparum parasites by examining the patterns of scattergrams.
Conclusions: The information on the MI-RBC#, MI-RBC% and the malaria parasite species could be obtained accurately and very rapidly by the XN-30 that will be useful for supporting clinical malaria diagnosis.