Abstract: Objective To explore the size changes of erythrocytes infected with Plasmodium malariae，so as to improve the basic?level experimenters’microscopy capabilities for P. malariae identification in thin blood smears. Methods The micro? scopic features of erythrocytes infected with P. malariae in thin peripheral blood smears were observed，and a microscope image processing software was used to measure and analyze the diameter changes of the erythrocytes infected with P. malariae. Re? sults The diameter of erythrocytes infected with P. malariae decreased significantly compared with that of the normal erythro? cytes. The three parameters in this study：the diameter of erythrocytes，the value of diameter variation，and the ratio of diameter variation varied at different developmental stages of P. malariae，and the differences were statistically significant（all P < 0.01）. The variances of the three parameters grouped by different cases or different developmental stages in different cases were ana? lyzed，all showing statistically significant differences（all P< 0.01）. Conclusion All the developmental stages of P. malariae will cause the decrease of the diameters of infected erythrocytes in peripheral blood smears，but the influence on the diameter of erythrocytes，valueofdiametervariation，and ratio of diameter variation varies at different developmental stages in different cases.

Key words: Plasmodium malariae；Erythrocytes；Diameter

摘要： 目的探讨三日疟原虫寄生红细胞的大小变化，提高基层实验人员对三日疟原虫血涂片的镜检能力。方法 观察三日疟原虫寄生红细胞的镜下特点，应用显微镜图像处理软件测量和分析三日疟原虫寄生红细胞的直径变化。结 果三日疟原虫寄生红细胞直径较正常红细胞缩小（P < 0.001），不同发育阶段原虫寄生红细胞直径、直径的变化值和直 径变化比差异均具有统计学意义（P 均< 0.001）；原虫寄生红细胞直径、直径的变化值和直径变化比在不同病例或不同病 例的不同发育阶段间差异均具有统计学意义（P均< 0.001）。结论各发育阶段三日疟原虫寄生红细胞均会导致外周血 涂片红细胞直径减小，但是不同患者不同发育阶段原虫对寄生红细胞直径、直径变化和直径变化比的影响不一致。

关键词: 三日疟原虫；红细胞；直径