[Quality of blood smear examinations for malaria parasites in Chenzhou City after malaria elimination].

OBJECTIVE: To analyze the quality of blood smear examinations for malaria parasites in Chenzhou City, so as to provide insights into sustainable consolidation of malaria elimination achievements.

METHODS: All positive blood smears from fever patients were irregularly sampled from each county (district) of Chenzhou City from 2018 to 2022 and reexamined, and no less than 3% negative blood smears were reexamined. The preparation, dyeing, cleanliness and microscopic examination results of blood smear were reexamined, and the quality of blood smear reexaminations was assessed using a descriptive statistical method.

RESULTS: A total of 13 625 fever patients received blood smear examinations for malaria parasites in Chenzhou City from 2018 to 2022, of which 21 were positive and 13 604 were negative; 687 blood samples were reviewed, and the percentage of negative blood smear reexaminations was 4.90% (666/13 604), with a 63.51% rate of qualified negative blood smears preparation, a 67.87% rate of qualified dyeing and a 76.13% rate of qualified cleanliness, and no missing diagnosis found. There were 21 positive blood smears reexamined, and the proportions of qualified blood smears preparation, dyeing and cleanliness were all 85.71%, with 2 smears mistaking Plasmodium species (9.52%). The percentage of qualified negative blood smears preparation was 51.41% in 2022, which reduced by 31.61% in relative to that (75.17%) in 2019 (χ2 = 9.033, P < 0.05), and the percentage of qualified negative blood smears dyeing was 60.19% in 2022, which reduced by 28.82% in relative to that (84.56%) in 2019 (χ2 = 19.498, P < 0.05), while the percentage of qualified negative blood smears cleanliness was 62.96% in 2022, which reduced by 28.93% in relative to that (88.59%) in 2019 (χ2 = 23.826, P < 0.001). In addition, there were no significant differences in the proportion of qualified negative blood smears preparation (χ2 = 0.260, P > 0.05) or dyeing (χ2 = 1.094, P > 0.05) among the three years, while a significant difference was detected in the percentage of qualified negative blood smears cleanliness (χ2 = 12.175, P < 0.05).

CONCLUSIONS: No missing diagnosis was seen in blood smear examinations for malaria parasites among fever patients in Chenzhou City after malaria elimination; however, there were reductions in proportions of qualified blood smears preparation, dyeing and cleanliness. Quality control of blood smear examinations is recommended to be reinforced in key regions of Chenzhou City.