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.
[摘要] 目的 分析郴州市消除疟疾后疟原虫血片质量, 为持续巩固消除疟疾成果提供科学依据。方法 2018—2022 年, 不定期抽取郴州市各县 (市、区) 发热病人疟原虫血片, 阳性血片全部进行复核、阴性血片抽检数量不少于总数的 3%。对血片制作、染色、清洁度及镜检结果进行复核, 采用描述性统计方法对血片质量复核结果进行分析。结果 2018—2022 年, 郴州市累计开展发热患者疟原虫血检 13 625人, 其中检出疟原虫阳性 21 人、阴性 13 604 人。共复核血片 687 张, 阳性血片 21 张、阴性血片 666 张, 阴性血片复核率 4.90% (666/13 604), 阴性血片制作合格率为 63.51%、染色合格率为 67.87%、清洁度合格率为 76.13%, 未发现漏检; 复核所有阳性血片 21 张, 制作合格率、染色合格率和清洁度合格率均为 85.71%, 发现分型错误血片 2 张 (9.52%)。2022 年阴性血片制作合格率为 51.41%, 较 2019 年显著下降 (χ2 = 9.033, P < 0.05); 2022年阴性血片染色合格率为 60.19%, 较 2019 年显著下降 (χ2 = 19.498, P < 0.001); 2022 年阴性血片清洁度合格 率为 62.96%, 较2019年显著下降 (χ2 = 23.826, P < 0.001)。2020—2022 年阴性血片制作合格率 (χ2 = 0.260, P > 0.05)、染 色合格率 (χ2 = 1.094, P > 0.05) 差异均无统计学意义, 但清洁度合格率差异有统计学意义 (χ2 = 12.175, P < 0.05)。结论 疟疾消除后, 郴州市发热患者疟原虫血检未出现漏检现象, 血片制作、染色和清洁度合格率有所下降, 应加强重点地区 血片质量控制。.