Blood analyzer and blood analyzing method

A blood analyzing method comprising:

• mixing a blood specimen and a fluorescent dye to prepare a measurement sample in which nucleic acids of Plasmodia parasitizing in red blood cells are stained;
• irradiating light to the measurement sample;
• detecting a fluorescence and a scattered light from individual cells in the measurement sample, caused in response to the irradiation;
• and
• identifying, based on the detected fluorescence and the detected scattered light, cells having a similar characteristic to single-ring form;
• and
• creating a histogram of the identified cells with respect to a fluorescence intensity to analyze a variation of a distribution of the cells, wherein the variation smaller than a threshold value is indicative of the identified cells being single-ring form, and the variation equal to or greater than the threshold value is indicative of the identified cells being non-malaria infected cells.

A blood analyzer comprising:

• a sample preparation unit comprising a reactor configured to mix a blood specimen and a fluorescent dye for staining a nucleic acid to prepare a measurement sample in which nucleic acids of Plasmodia parasitizing in red blood cells are stained;
• a light sensor configured to receive fluorescence and scattered light from individual cells in response to light irradiated onto the measurement sample;
• and
• a processor programmed to:
• plot the individual cells on a coordinate plane having an axis of fluorescence intensity and an axis of scattered light intensity;
• count cells plotted in a first region on the coordinate plane where malaria-infected cells are plotted;
• obtain a value representing a variation of a distribution of cells appearing in a second region that is a narrowed part of the first range;
• and
• determine Plasmodium infection positive responsive to determining that the value representing the variation of the distribution in the second range is less than a threshold value and the number of cells in the first range is greater than a threshold value.