title: Differences in automated depolarization patterns of Plasmodium falciparum and P. vivax malaria infections defined by the Cell-Dyn CD4000 haematology analyser.
abstract: Of 1014 samples submitted for full blood count analysis and malaria screening, 854 were designated malaria-negative by blood film microscopy, 79 were unequivocally identified as Plasmodium vivax and 81 as P. falciparum. All samples were additionally analysed with the Abbott Cell-Dyn CD4000 haematology instrument, and leucocyte differential plots of 90 degrees polarized vs. 90 degrees depolarized (NEU-EOS plot) and 90 degrees depolarized vs. 0 degree light (EOS I plot) scatter were specifically examined for abnormal depolarization patterns. Depolarization pattern types were correlated with microscopy (species) results, and these correlations were consolidated by polymerase chain reaction analysis. All 854 microscopically-designated malaria-negative samples showed a type 1 (normal) CD4000 depolarization pattern. Abnormal pattern types 2, 3a and 3b were entirely restricted to one of the two malaria categories. Plasmodium falciparum malaria showed two CD4000 pattern types only; a 'normal' type 1 pattern was seen in 36/75 (48%) cases and the remaining 39 cases were all abnormal pattern type 3a. In contrast, most (79/85) P. vivax malaria cases showed a distinctive clustered EOS I population (types 2 and 3b patterns) that was not seen with P. falciparum. Automated depolarization analysis provides an effective means of detecting malaria-associated haemozoin, and the patterns of intracellular haemozoin further appear to provide species differentiation between P. falciparum and P. vivax.
authors.affiliation: Haematology Section, Department of Laboratory Medicine and Pathology, Hamad Medical Corporation, P.O. Box 3050, Doha, Qatar.
authors.forename: Zainab O
authors.initials: ZO
authors.lastname: Fawzi
authors.forename: Naila A
authors.initials: NA
authors.lastname: Fakhro
authors.forename: Randa A
authors.initials: RA
authors.lastname: Nabhan
authors.forename: Ali
authors.initials: A
authors.lastname: Alloueche
authors.forename: Colin Stephen
authors.initials: CS
authors.lastname: Scott
mesh_terms: D000818:Animals; D004804:Eosinophils / Q000378:metabolism / Q000469:parasitology; D006420:Hemeproteins / Q000378:metabolism; D006801:Humans; D016778:Malaria, Falciparum / Q000175:diagnosis*; D016780:Malaria, Vivax / Q000175:diagnosis* / Q000469:parasitology; D008859:Microscopy, Polarization / Q000379:methods*; D009000:Monocytes / Q000378:metabolism / Q000469:parasitology; D010274:Parasitology / Q000379:methods; D010963:Plasmodium falciparum / Q000302:isolation & purification; D010966:Plasmodium vivax / Q000302:isolation & purification
chemical_list: D006420:Hemeproteins; C020753:hemozoin