RESUMO
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 microscopic 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. RESULTS: The diameter of erythrocytes infected with P. malariae decreased significantly compared with that of the normal erythrocytes. 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 analyzed, all showing statistically significant differences (all P< 0.01). CONCLUSIONS: 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, value of diameter variation, and ratio of diameter variation varies at different developmental stages in different cases.