Abstract: Objective　To analyze the epidemiological characteristics and diagnosis of imported malaria before and after malaria elimination in Nanjing City of Jiangsu Province, so as to provide the scientific evidence for formulating the malaria control strategy after malaria elimination. Methods　Data pertaining to the epidemic situation and individual investigation of malaria in Nanjing City before (from 2012 to 2016) and after malaria elimination (from 2017 to 2020) were captured from the National Notifiable Communicable Disease Reporting System and the Information System for Parasitic Diseases Control and Prevention and were analyzed statistically. Results　A total of 178 malaria cases were reported in Nanjing City from 2012 to 2020, and all were imported cases. There were 99 malaria cases reported before malaria elimination in Nanjing City, including 78 cases with Plasmodium falciparum malaria (78.79%), 5 cases with P. vivax malaria (5.05%), 10 cases with P. ovale malaria (10.10%), 3 cases with P. malariae malaria (3.03%) and 3 cases with mixed infections (3.03%), and 79 malaria cases reported after elimination, including 63 cases with P. falciparum malaria (79.75%), 5 cases with P. vivax malaria (6.33%), 9 cases with P. ovale malaria (11.39%), 2 cases with P. malariae malaria (2.53%). There was no significant difference in the proportion of each type of malaria cases in Nanjing City before and after malaria elimination ([χ2] = 2.400, P > 0.05). Malaria cases mainly acquired Plasmodium infections in African regions, and no significant difference was seen in the proportion of malaria cases returning to Nanjing City from African countries before and after malaria elimination ([χ2] = 0.093, P > 0.05). The number of malaria cases peaked in Nanjing City in January and during the period from May to July before elimination, and there was no apparent seasonal variation in the distribution of malaria cases after elimination. The proportion of malaria cases living in Nanjing City was significantly greater after malaria elimination than before elimination (72.15% vs. 55.56%; [χ2] = 5.187, P = 0.023). The proportions of businessmen and international students were both 5.05% before malaria elimination, and increased to 15.19% and 13.92% after elimination, respectively ([χ2] = 5.229 and 4.229, both P values < 0.05). The percentage of definitive diagnosis of malaria at initial diagnosis was 18.75% in county⁃level hospitals before malaria elimination and increased to 61.11% after elimination ([χ2] = 6.275, P = 0.012), while the proportion of malaria cases with definitive diagnoses in county⁃level hospitals was 4.04% before malaria elimination and increased to 13.92% after elimination ([χ2] = 5.562, P = 0.018). During the period from 2012 to 2020, the proportion of malaria cases with definitive diagnoses within 1 to 3 days post⁃admission increased from 27.27% in Nanjing City before malaria elimination to 45.57% after elimination ([χ2] = 6.433, P = 0.011). Conclusions　The epidemic situation of imported malaria remains serious in Nanjing City during the post⁃elimination stage, and malaria parasite infections predominantly occur in African regions. In addition, there are changes in regional and occupational distributions of malaria cases and the diagnostic capability of malaria increases in county⁃level hospitals in Nanjing City after malaria elimination. Further improvements in the malaria surveillance system and the diagnostic and treatment capability of malaria in medical institutions at each level are required to consolidate malaria elimination achievements in Nanjing City.

Key words: Malaria, Elimination, Imported case, Epidemic situation, Nanjing City

摘要： 目的　对江苏省南京市疟疾消除前后输入性疟疾疫情特征及诊断进行比较分析，为制定消除疟疾后防控策略提供科学依据。方法　通过国家传染病报告信息管理系统和寄生虫病防治信息管理系统，收集南京市疟疾消除前（2012—2016年）和消除后（2017—2020年）疟疾疫情数据及病例流行病学个案调查资料，进行统计分析。结果　2012—2020年，南京市累计报告疟疾病例178例，均为境外输入性病例。消除前报告99例疟疾病例，其中恶性疟78例（78.79%）、间日疟5例（5.05%）、卵形疟10例（10.10%）、三日疟3例（3.03%）、混合感染3例（3.03%）；消除后报告79例病例，其中恶性疟63例（79.75%）、间日疟5例（6.33%）、卵形疟9例（11.39%）、三日疟2例（2.53%）；疟疾消除前后，各类疟疾病例所占比例差异无统计学意义（[χ2] = 2.400，P > 0.05）。病例感染地均以非洲地区为主，消除前后来源于非洲的病例占比差异无统计学意义（[χ2] = 0.093，P > 0.05）。消除前，1月和5—7月出现疟疾病例报告高峰；消除后病例分布无明显季节性。消除疟疾后，居住地为南京市的疟疾病例数占报告病例总数的72.15%，高于消除前的55.56%（[χ2] = 5.187, P = 0.023）。消除前，经商人员和留学生疟疾病例所占比例均为5.05%；消除后，两类人群所占比例分别提高至15.19%和13.92%，差异均有统计学意义（[χ2] = 5.229、4.229, P均＜0.05）。区（县）级医院首诊确诊率由消除前的18.75%上升至消除后的61.11%（[χ2] = 6.275, P = 0.012），确诊病例占比由消除前的4.04%上升至消除后的13.92%（[χ2] = 5.562, P = 0.018）。2012—2020年，就诊后1～3 d确诊的疟疾病例占比由消除前的27.27%上升至消除后的45.57%，差异有统计学意义（[χ2] = 6.433, P = 0.011）。结论　南京市疟疾消除后，输入性疟疾疫情依然严峻，病例感染地仍以非洲地区为主，病例地区分布和职业分布发生变化，区（县）级医院诊断水平提高。今后应继续完善疟疾监测体系，进一步提升各级医疗卫生机构疟疾诊治水平，以巩固消除成果。 　

关键词: 疟疾, 消除, 输入性病例, 疫情, 南京市