Data_Sheet_1_Increasing incidence of Plasmodium ovale and persistent reporting of Plasmodium vivax in imported malaria cases: an analysis of 9-year surveillance data in four areas of China.docx

BackgroundThis study aimed at exploring the epidemiological pattern of imported malaria in China before malaria elimination in 2021, to provide evidence-based data for preventing malaria re-establishment in China.
MethodsNine-year surveillance data on imported malaria in four provincial-level administrative divisions (PLADs) (Anhui, Chongqing, Guangxi, and Zhejiang) between 2011 and 2019 were thoroughly collected and analyzed.
ResultsA quite stable trend in imported malaria cases between 2011 and 2019 was observed. In total, 6,064 imported patients were included. Plasmodium falciparum was the most frequently reported species (4,575, 75.6%). Cases of malaria were most frequently imported from Western Africa (54.4%). We identified an increasing trend in P. ovale and a persistence of P. vivax infections among the cases of malaria imported from Western Africa. Most patients (97.5%) were 20–50 years old. Among imported malaria infections, the main purposes for traveling abroad were labor export (4,914/6,064, 81.0%) and business trips (649, 10.7%). Most patients (2,008/6,064, 33.1%) first visited county-level medical institutions when they sought medical help in China. More patients were diagnosed within 3 days after visiting Centers for Disease Control and Prevention (CDCs) or entry–exit quarantine facilities (EQFs) (1,147/1609, 71.3%) than after visiting medical institutions (2,182/3993, 54.6%).
ConclusionImported malaria still poses a threat to the malaria-free status of China. County-level institutions are the primary targets in China to improve the sensitivity of the surveillance system and prevent the re-establishment of malaria. Health education should focus on exported labors, especially to Western and Central Africa. Increasing trend in P. ovale and persistence of P. vivax infections indicated their underestimations in Western Africa. Efficient diagnostic tools and sensitive monitoring systems are required to identify Plasmodium species in Africa.

研究背景：本研究旨在探究2021年中国消除疟疾前境外输入性疟疾的流行病学特征，为防范我国疟疾再度建立本土传播提供循证依据。
研究方法：系统收集并分析了2011至2019年安徽、重庆、广西、浙江4个省级行政区（provincial-level administrative divisions, PLADs）的9年境外输入性疟疾监测数据。
研究结果：2011至2019年我国境外输入性疟疾病例整体呈现相对稳定的态势，共计纳入6064例输入性疟疾病例。其中恶性疟原虫（Plasmodium falciparum）为最常见感染虫株（4575例，占75.6%）；病例主要输入来源地为西非地区（54.4%）。在来自西非的输入性疟疾病例中，卵形疟原虫（P. ovale）感染呈上升趋势，间日疟原虫（P. vivax）感染则持续存在。患者年龄以20~50岁群体为主，占比达97.5%。境外出行的主要目的为劳务输出（4914例，占81.0%）及商务出行（649例，占10.7%）。就诊初期选择县级医疗机构的患者占比最高（2008/6064，33.1%）。在就诊后确诊时间方面，前往疾病预防控制中心（Centers for Disease Control and Prevention, CDCs）或出入境检疫设施（entry–exit quarantine facilities, EQFs）的患者中，71.3%（1147/1609）可在3日内获得确诊，高于前往普通医疗机构的患者（54.6%，2182/3993）。
研究结论：境外输入性疟疾仍对我国无疟疾状态构成威胁。县级医疗机构是提升我国疟疾监测系统敏感性、防范疟疾再度建立本土传播的核心防控节点。健康教育应重点面向劳务输出人群，尤其是前往西非及中非地区的群体。卵形疟原虫感染的上升趋势与间日疟原虫感染的持续存在，提示西非地区对该两类疟原虫的识别存在低估。需依托高效诊断工具与灵敏监测系统，实现非洲地区疟原虫虫株的精准鉴别。