Abstract: Objective　To investigate the epidemiological characteristics of imported malaria cases in Shanghai Municipality from 2020 to 2024, so as to provide insights into dynamic adjustment of imported malaria control strategies. Methods　All data pertaining to malaria cases reported in Shanghai Municipality from 2020 to 2024 were collected from Infectious Diseases Reporting Information Management System and Parasitic Diseases Prevention and Control Information Management System of Chinese Center for Disease Control and Prevention, and epidemiological investigation reports of malaria cases. The type of malaria cases, source of acquiring infections, temporal, spatial and population distributions of malaria cases, type of initial diagnosis institutions, accuracy of initial diagnosis, time interval from disease onset to initial diagnosis, and the time interval from initial diagnosis to diagnosis were statistically analyzed. The monthly distribution of malaria cases was analyzed using a circular distribution method. Results　A total of 124 malaria cases were reported in Shanghai Municipality from 2020 to 2024, with 14, 52, 22, 8 and 28 cases annually, respectively, and all cases were overseas imported cases. Plasmodium falciparum malaria was the predominant type, accounting for 82.26% (102/124) of all malaria cases, while P. ovale, P. vivax and P. malariae malaria accounted for 8.06% (10/124), 7.26% (9/124) and 2.42% (3/124) of reported cases, respectively. Malaria cases acquired infections from 28 countries in 4 continents, with African countries as a major source of acquiring infections (96.77%, 120/124). Malaria cases were reported across all 16 districts in Shanghai Municipality. There were peaks in numbers of reported malaria cases in May 2021 (9 cases) and November 2021 (9 cases); however, there was no concentration trend in the reporting time of malaria cases from 2020 to 2024 (Z = 2.45，P > 0.05). The reported malaria cases included 116 males and 8 females, with a male⁃to⁃female ratio of 14.5 ∶ 1.0, and had a median age of 39 (17) years. Worker was the primary occupation of reported malaria cases, accounting for 48.39% (60/124) of all reported cases. City⁃level medical institutions were the predominant initial diagnosis institutions (75.81%, 94/124). The overall accuracy of initial diagnosis was 74.19% (92/124), and the median time interval from disease onset to initial diagnosis was 0 (2) day (healthcare seeking on the day of disease onset), with 72.58% (90/124) of malaria cases seeking healthcare services within one day. The median time interval from initial diagnosis to diagnosis was 2 (3) days, with 41.94% (52/124) of malaria cases that were definitively diagnosed within one day following initial diagnosis. There were significant differences in the accuracy of initial malaria diagnosis ([χ2] = 15.01，P < 0.05), the time interval from disease onset to initial diagnosis (H = 29.30, P < 0.001), and the time interval from initial diagnosis to diagnosis (H = 22.92, P < 0.001) among years from 2020 to 2024, and the time interval from disease onset to initial diagnosis (Z = -5.09, P < 0.001) and the time interval from initial diagnosis to diagnosis (Z = -4.14, P < 0.001) were both shorter during the period from 2020 to 2022 than those recorded from 2023 to 2024. In addition, a total of 2 malaria deaths were reported in Shanghai Municipality during the period from 2020 to 2024, both caused by P. falciparum malaria. Conclusions　The numbers of malaria cases fluctuated continuously in Shanghai Municipality from 2020 to 2024. It is recommended to continuously strengthen surveillance and response measures, improve malaria diagnosis and treatment capabilities, and conduct targeted health education activities among high⁃risk populations, such as labors going to overseas malaria hyper⁃endemic areas, so as to prevent re⁃establishment of imported malaria.

Key words: Malaria, Imported case, Epidemiological characteristic, Shanghai Municipality

摘要： 目的　分析2020—2024年上海市输入性疟疾流行特征，为动态调整输入性疟疾防控策略提供依据。方法　在中国疾病预防控制中心传染病报告信息管理系统、寄生虫病防治信息管理系统以及疟疾病例流行病学调查报告中收集2020—2024年上海市疟疾病例数据，对疟疾病例类型、感染来源、三间分布、初诊单位类型、初诊正确率、发病到初诊时间间隔、初诊到确诊时间间隔等进行统计分析，病例报告月份分布采用圆形分布法进行分析。结果　2020—2024年上海市共报告疟疾病例124例，各年分别报告14、52、22、8、28例，均为境外输入的确诊病例。报告病例以恶性疟为主，占82.26%（102/124），卵形疟、间日疟、三日疟病例分别占8.06%（10/124）、7.26%（9/124）、2.42%（3/124）。病例感染来源地分布于4个大洲的28个国家，以非洲国家为主，占96.77%（120/124）。上海市16个区均有病例报告，2021年5月（9例）和2021年11月（9例）为病例报告高峰，但2020—2024年疟疾病例报告时间无集中趋势（Z = 2.45，P > 0.05）。报告病例中，男性116例，女性8例，男女性别比为14.5∶1.0，年龄中位数（四分位数间距）［M（QR）］为39（17）岁，职业以工人为主，占48.39%（60/124）。报告病例初次就诊单位主要为地市级医疗机构，占75.81%（94/124），初诊正确率为74.19%（92/124），发病到初诊时间间隔M（QR）为0（2） d（发病当天就诊），72.58%（90/124）的病例在1 d内就诊；初诊到确诊时间间隔M（QR）为2（3） d，41.94%（52/124）的病例在初诊1 d内确诊；2020—2024年不同年份疟疾病例初诊正确率（[χ2] = 15.01，P < 0.05）、发病到初诊时间间隔（H = 29.30，P < 0.001）和初诊到确诊时间间隔差异（H = 22.92，P < 0.001）均有统计学意义；2020—2022年疟疾病例发病到初诊时间间隔（Z = −5.09，P < 0.001）、初诊到确诊时间间隔（Z = −4.14，P < 0.001）均短于2023—2024年。2020—2024年上海市共报告2例疟疾死亡病例，均为恶性疟病例。结论　2020—2024年上海市报告疟疾病例数呈波动趋势，应持续强化监测响应措施，加强疟疾诊疗能力，做好对往返境外疟疾高发地区的劳务人员等重点人群的健康教育宣传，防止疟疾输入再传播。

关键词: 疟疾, 输入性病例, 流行特征, 上海市