Spatiotemporal Characteristics and Risk Zonation Analysis of Rodents and Surface-Parasitic Fleas — Inner Mongolia Autonomous Region, China, 2013–2021

Meng Shang^1,2; Haoqiang Ji ^1,2,; Ke Li²; Xiaoxu Wang^1,2; Lu Wang^1,2; Wanjun Jiang^1,2; Ying Liang²; Qiyong Liu^1,2,#

1. Department of Vector Control, School of Public Health, Cheeloo College of Medicine, Shandong University, Jinan City, Shandong Province, China;

2. National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China;

^# Corresponding author: Qiyong Liu, liuqiyong@icdc.cn.

Recent plague cases in Inner Mongolia prompted research on rodents and fleas. This study aimed to describe the spatiotemporal characteristics of parasitic fleas on predominant rodent species and identify plague risk areas. We assembled monitoring data from the National Plague Surveillance System for 12 regions in Inner Mongolia from 2013 to 2021. We performed descriptive statistics using relative indices, analyzed interannual flea index trends using the Mann-Kendall test, compared spatiotemporal characteristics using the Kruskal-Wallis H test and Dunn's test, and delineated plague risk areas based on cluster analysis. In total, 134,181 rodents belonging to 28 species across four families were captured in Inner Mongolia. Among them, 42,216 rodents were parasitized by fleas, with an average parasitism rate of 31.46%. A total of 143,958 fleas were collected, resulting in a total average flea index of 1.07. The predominant rodent species were the Mongolian gerbil, Meriones unguiculatus and Daurian ground squirrel, Spermophilus dauricus. The overall flea index showed a decreasing trend (Sen's slope=–0.06, P<0.05). M. unguiculatus exhibited two seasonal peaks (May and October), with a delay of one to two months after peak flea parasitism. S. dauricus had a single seasonal peak in May but two flea parasitism peaks (March and November). M. unguiculatus and S. dauricus flea indices varied significantly across regions (H=25.75, P<0.001; H=29.88, P<0.001). Erdos City and Xilingol League had the highest cumulative flea indices for each species, respectively. Cluster analysis divided the 12 regions into three risk zones. The two predominant rodent species in Inner Mongolia have demonstrated an overall decline in flea index over time. The hotspots for flea index are primarily concentrated in Erdos and Xilingol League. Strengthening regional cooperation is crucial for tailored plague prevention and control measures.

啮齿动物及其体表寄生蚤时空特征和风险区划分析 — 内蒙古自治区，中国，2013–2021年

尚猛^1,2；冀好强^1,2；李轲²；王晓旭^1,2；王璐^1,2；姜宛均^1,2；梁莹²；刘起勇^1,2

1. 山东大学齐鲁医学院公共卫生学院媒介生物控制学系，济南市，山东省，中国；

2. 传染病溯源预警与智能决策全国重点实验室，中国疾病预防控制中心传染病预防控制所，北京，中国；

^# 通信作者：刘起勇，liuqiyong@icdc.cn。

近期在内蒙古发生的鼠疫病例引发了对啮齿动物和蚤类的研究。本研究旨在描述主要啮齿动物寄生蚤的时空特征，并识别鼠疫高风险区域。该研究从国家鼠疫监测系统收集了2013-2021年内蒙古12个地区的监测数据。采用相对数指标进行描述性统计，通过Mann-Kendall检验分析蚤指数的年际变化趋势，使用Kruskal-Wallis H检验和Dunn's检验比较时空特征，并基于聚类分析划定鼠疫风险区域。在内蒙古共捕获134,181只啮齿动物，涉及4科28种。其中42,216只啮齿动物被蚤寄生，平均寄生率为31.46%。共采集到143,958匹体表寄生蚤，总均蚤指数为1.07。主要的啮齿动物为长爪沙鼠（Meriones unguiculatus）和达乌尔黄鼠（Spermophilus dauricus）。总体蚤指数呈下降趋势（Sen's slope=-0.06, P<0.05）。M. unguiculatus在5月和10月出现两个季节性高峰，且峰值出现在蚤寄生高峰后的1-2个月。S. dauricus在5月有一个季节性高峰，但在3月和11月出现两个蚤寄生高峰。M. unguiculatus和S. dauricus的蚤指数在地区间差异显著（H=25.75, P<0.001；H=29.88, P<0.001）。鄂尔多斯市和锡林郭勒盟分别是两种啮齿动物蚤指数最高的地区。聚类分析将12个地区分为三类风险区。内蒙古的两种主要啮齿动物的蚤指数整体呈下降趋势，蚤指数的热点主要集中在鄂尔多斯和锡林郭勒盟。加强区域合作对于制定有针对性的鼠疫防控措施至关重要。

For more information: https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2024.241

Epidemiological Features and Spatial-Temporal Clustering of Visceral Leishmaniasis — China, 2011–2022

Zhengbin Zhou¹; Zhuowei Luo²; Gaiqin Pan³; Yuanyuan Li^1,; Zhongqiu Li,¹ Qin Liu¹; Yuwan Hao¹; Limin Yang¹; Zelin Zhu¹; Qiang Wang¹; Yi Zhang^1,4; Shizhu Li^1,4,#

¹ National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, National Institute of Parasitic Diseases at Chinese Center for Disease Control and Prevention, Chinese Center for Tropical Diseases Research; NHC Key Laboratory of Parasite and Vector Biology; WHO Collaborating Center for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology, Shanghai, China;

² Beijing Center for Disease Prevention and Control, Beijing, China.

³ Liaocheng People's Hospital, Liaocheng City, Shandong Province, China;

⁴ School of Global Health, Chinese Center for Tropical Diseases Research-Shanghai Jiao Tong University School of Medicine, Shanghai, China.

^# Corresponding author: Shizhu Li, lisz@chinacdc.cn.

Visceral leishmaniasis (VL), transmitted by sandflies, is a zoonotic disease of public health importance in central and western China. This study is to elucidate the current epidemiological features and spatial-temporal clustering of visceral leishmaniasis in order to provide evidence for further strategies. Data on VL cases in the Chinese mainland from 2011 to 2022 were collected from the NNDRS. Indigenous and imported cases were defined according to epidemiological investigations of individual cases. Joinpoint regression was used to identify turning points and divide the disease incidence trend into statistically significant sections. Getis-Ord Gi* statistical data in ArcGIS were used for hotspot analysis. Spatial-temporal cluster analysis was conducted using retrospective space-time permutation scan statistics using a flexible spatial scan statistic in SaTScan software. All incidence data were processed separately for the 3 years for which data were available, and potential spatial clusters were detected using the restricted log likelihood ratio (RLLR). A Monte Carlo simulation was used for permutation testing, with statistical significance determined by P value. A P<0.05 indicated a statistically significant cluster. From 2011 to 2022, 3,041 VL cases were reported from 400 counties in 24 PLADs. Of these, 2,572 (84.6%) were indigenous cases that occurred in 124 endemic counties. These cases comprised 173 anthroponotic visceral leishmaniasis (AVL), 788 desert-type zoonotic visceral leishmaniasis (DT-ZVL), and 1,611 mountain zoonotic visceral leishmaniasis (MT-ZVL) cases . The remaining 469 (15.4%) cases were imported to 276 non-endemic counties. The incidence of MT-ZVL declined during 2011–2015 (APC=–17.98, P<0.05) but increased significantly during 2015–2022 (APC=14.06, P<0.05). Conversely, the incidence of DT-ZVL increased rapidly during 2011–2015 (APC=163.20, P<0.05) and decreased during 2015–2022 (APC=–57.75, P<0.05). Overall, the incidence of AVL showed a slight decline between 2011 and 2022. Approximately three-quarters of VL cases were distributed across three provinces: Xinjiang (n=947, 31.1%), Gansu (n=829, 27.3%), and Shanxi (n=481, 15.8%) PLADs. Among 118 endemic counties these counties, three were responsible for 43.9% (1,130/2,572) of indigenous cases: Jiashi County (637 cases) in Xinjiang, and Wudu District (283 cases) and Zhouqu County (210 cases) in Gansu Province. Sixty-eight counties in seven PLADs were identified as re-emerging areas between 2011 and 2022 with a total of 675 indigenous cases reported, most of which (671/675) were the MT-ZVL type. Major high-incidence regions were observed in southern Gansu Province and northern Sichuan Province from 2011 to 2019, in southern Xinjiang Uygur Autonomous Region from 2014 to 2016, and in the border areas of Shanxi-Hebei provinces and Shanxi-Shaanxi provinces from 2019 to 2022. VL cases occurred mainly in preschool children, particularly those aged 0–2 years, who accounted for 42.3% (n=1,285) of all cases. In terms of occupation, farmers were the most affected population, excluding preschool children. The peak incidence of DT-ZVL occurred from April to May, while that of MT-ZVL occurred from October to November. Actions are recommended to restrain the rapid expansion of MT-ZVL: Firstly, implement One Health approaches, such as timely diagnosis and treatment of patients, promoting insecticide-impregnated dog collars, and restraining the number of dogs in endemic areas. Secondly, strengthen surveillance-response systems for sandflies and infective dogs in potential risk areas.

.

内脏利什曼病流行病学特征及时空聚类分析 — 中国，2011–2022年

周正斌¹；罗卓韦²；潘改芹³；李元元¹；李中秋；刘琴¹；郝瑜婉¹；杨丽敏¹；朱泽林¹；王强¹；张仪^1,4；李石柱^1,4#

1.传染病溯源预警与智能决策全国重点实验室,中国疾病预防控制中心寄生虫病预防控制所,国家热带病研究中心；国家卫生健康委员会寄生虫病原与媒介生物学重点实验室；世界卫生组织热带病合作中心；科技部国家级热带病国际研究中心，上海，中国；

2.北京市疾病预防控制中心，北京，中国；

3.山东省聊城市人民医院，聊城市，山东省，中国；

4.上海交通大学医学院-国家热带病研究中心全球健康学院，上海,中国。

^# 通信作者：李石柱，lisz@chinacdc.cn。

内脏利什曼病（VL）是一种由白蛉传播的人畜共患疾病，做好其防控在中国中西部地区具有重要的公共卫生意义。本研究旨在阐明目前内脏利什曼病的流行病学特征和时空聚类，为进一步的策略提供依据。收集2011-2022年中国大陆VL病例数据。根据病例的流行病学调查，确定本地病例和输入病例。采用Joinpoint回归模型来识别VL的发病趋势，并将疾病的发病率趋势划分为具有统计意义的不同部分。利用ArcGIS中的Getis-Ord Gi*统计法进行热点分析。采用SaTScan软件中空间扫描统计量，实施回顾性时空重排扫描来进行时空聚类分析。对所有可获得的发病率数据按年份分别处理，并使用对数似然比（RLLR）检测潜在的空间聚类情况。采用蒙特卡罗模拟进行排列检验，当P值<0.05时，表示聚类结果具有统计学意义。2011-2022年，24个省份400个县共报告VL病例3041例。其中，2572例（84.6%）是发生在124个流行县的本地感染病例。其中人源型内脏利什曼病(AVL) 173例，荒漠型内脏利什曼病(DT-ZVL) 788例，山丘型内脏利什曼病(MT-ZVL) 1611例。其余469例（15.4%）病例为276个非流行县输入病例。2011-2015年MT-ZVL发病率下降（APC=-17.98， P<0.05）， 但2015-2022年MT-ZVL发病率显著上升（APC=14.06， P<0.05）。相反，2011-2015年DT-ZVL发病率快速上升（APC=163.20， P<0.05）， 而2015-2022年下降（APC= -57.75， P<0.05）。总体而言，AVL的发病率在2011年至2022年间略有下降。大约75%的VL病例分布在三个省：新疆（n=947, 31.1%）、甘肃（n=829, 27.3%）和山西（n=481, 15.8%）。118个流行县中，有3个县占本地病例的43.9%(1130/2572)，分别是新疆伽师县（637例）、甘肃省武都区（283例）和舟曲县（210例）。2011年至2022年期间，7个省份的68个县被确定为复燃流行县，共报告了675例本地感染病例，其中大多数（671/675）为MT-ZVL型。2011-2019年主要高发区为甘肃南部和四川北部，2014 - 2016年主要高发区为新疆维吾尔自治区南部，2019-2022年主要高发区为晋冀和晋陕边境地区。VL病例以学龄前儿童为主，以0-2岁儿童为主，占全部病例的42.3% （n=1285）。就职业而言，农民是除学龄前儿童外受影响最大的人群。DT-ZVL的发病高峰出现在4-5月，MT-ZVL的发病高峰出现在10-11月。抑制MT-ZVL快速蔓延的措施：一是实施“全健康”方针，及时诊治患者，推广犬驱项圈，控制疫区犬只数量；其次，在潜在风险地区加强对白蛉和感染犬的监测相应体系建设。

For more information: https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2024.242.

Pilot Surveillance of Babesia, Borrelia burgdorferi, and Anaplasma phagocytophilum Among Chinese Blood Donors — Xinjiang, Inner Mongolia, and Heilongjiang PLADs, China, 2022–2023

Huimin Ji¹; Le Chang ^1,2; Ying Yan¹; Huizhen Sun¹; Lunan Wang^1,2,＃

1. National Center for Clinical Laboratories, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing Hospital/National Center of Gerontology, Beijing, China

2. Graduate School, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China.

^# Corresponding author: Lunan Wang, lnwang@nccl.org.cn.

This study aimed to assess the prevalence of Babesia, Borrelia burgdorferi (B. burgdorferi), and Anaplasma phagocytophilum (A. phagocytophilum) in areas with high tick distribution, which provides valuable insights into potential infection risks. In this study, we developed a quality control system for nucleic acid testing (NAT) screening for Babesia, B. burgdorferi, and A. phagocytophilum, evaluated the efficacy of five Chinese Triplex-NAT kits for these pathogens, and conducted an external quality assessment (EQA) of blood centers to guarantee screening quality. From June to July or July to August 2022–2023, 18 blood centers in the border areas of Heilongjiang, Inner Mongolia, and Xinjiang conducted nucleic acid screening for tick-borne pathogens on all blood donors. Samples that showed initial reactive results were sent to the National Clinical Laboratory Center for confirmation. Each of the five kits demonstrated excellent repeatability and reproducibility with high within-run and within-laboratory precision (CV value of <5%), but the LoDs differed among reagents. All participating laboratories had EQA scores exceeding 80. During the two-year surveillance process, a total of 92,700 blood donors were screened for tick-borne pathogens. A blood donor in Hegang, Xinjiang, tested positive for B. burgdorferi (1/4,629, 0.22‰), which is the first instance of detection of a B. burgdorferi infection in Chinese blood donors. Our study highlights the potential presence of tick-borne pathogens in Chinese blood donors. Therefore, enhanced screening strategies using reliable quality control systems and highly sensitive assays are crucial for detecting infected blood units. To further guarantee the security of blood transfusions, screening should be strengthened in high-risk locations outside border regions.

献血者中巴贝虫、伯氏疏螺旋体和嗜吞噬细胞无形体试点监测 — 新疆、内蒙古和黑龙江, 中国，2022–2023年

姬慧敏¹；常乐^1,2；闫颖¹；孙慧珍¹；王露楠^1,2#

1. 北京医院，国家老年医学中心，国家卫生健康委临床检验中心，中国医学科学院老年医学研究院，北京，中国；

2. 中国医学科学院，北京协和医学院研究生院，北京，中国。

^# 通讯作者: 王露楠：lnwang@nccl.org.cn。

本研究旨在评估蜱媒传播病原体（巴贝虫、伯氏疏螺旋体和嗜吞噬细胞无形体）在中国蜱虫流行地区献血者中的流行情况，为探究潜在感染风险提供依据。本研究通过建立针对巴贝虫、伯氏疏螺旋体和嗜吞噬细胞无形体的核酸检测（NAT）质量控制系统，对五种国产三联检NAT试剂进行性能评价，并对参与筛查的实验室进行室间质量评价（EQA）以确保筛查质量。黑龙江、内蒙古和新疆边境地区的18家血站对2022-2023年6月-7月或7-8月期间的所有献血者进行蜱媒病原体核酸筛查，初筛反应性样本送至国家卫生健康委临床检验中心进行确认。五种检测试剂的室内和室间精密度均良好（CV值<5%），但各试剂的最低检出限（LoD）存在差异。所有参与筛查的实验室的EQA得分均超过80分。在为期两年的监测过程中，共对92,700名献血者进行了蜱媒病原体的筛查，1例新疆鹤岗市的献血者确认为伯氏疏螺旋体核酸阳性（1/4,629，0.22‰），这是首次在中国献血者中发现伯氏疏螺旋体的感染。本研究提示蜱媒传播病原体在中国献血者中存在的可能性。因此，采用可靠的质量控制系统和灵敏的检测方法、加强筛查策略对确保血液安全至关重要。此外，应在边境区域以外的高风险地点加强筛查，以进一步保证血液安全。

For more information: https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2024.243

A Longitudinal Analysis of Antibody Dynamics in Severe Fever with Thrombocytopenia Syndrome Patients — High-Incidence Regions of China, 2010–2023

Yanhan Wen^1*; Dongmei Song^2*; Aqian Li^1*; Lina Sun¹; Shuhua Ma²; Tiezhu Liu¹; Xiaoxia Huang¹; Tao Huang¹; Boyang Li¹; Mengxuan Wang¹; Jiandong Li¹; Mifang Liang¹; Dexin Li¹; Wei Wu^1,#; Xinxian Dai^2,#; Shiwen Wang^1,#

1. National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, NHC Key Laboratory of Medical Virology and Viral Diseases, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China

2.  National Vaccine and Serum Institute, Beijing, China.

* Joint first authors.

# Corresponding author: Wei Wu, wuwei@ivdc.chinacdc.cn; Xinxian Dai, daixinxian@sinopharm.com; Shiwen Wang, wangsw@ivdc.chinacdc.cn.

This study aimed to characterize the longitudinal antibody kinetics in patients with severe fever with thrombocytopenia syndrome (SFTS) from high-incidence regions in China between 2010 and 2023 (with follow-up periods extending up to 10 years from symptom onset), to support vaccine development, optimize therapeutic strategies, and enhance diagnostic capabilities. A longitudinal analysis of 1,410 serum samples from 1,233 patients with confirmed SFTS was conducted.  IgM, IgG, and neutralizing antibody (NAb) levels were quantified, and their associations with viral load, clinical parameters, and demographic characteristics were evaluated. IgM levels peaked at 8–14 days after symptom onset and declined to near-undetectable levels by 180 days, while IgG and NAb levels peaked at 22–180 days and persisted for up to 10 years. IgM levels correlated significantly with viral load and multiple clinical parameters, with lower levels observed in fatal cases. Elderly patients exhibited reduced IgG levels during convalescence, while female patients had higher IgG levels than male patients. This study elucidates the long-term antibody dynamics in SFTS patients, highlighting the diagnostic utility of IgM in early infection and the persistence of IgG and NAb as indicators of durable immune protection. These findings provide a scientific basis for vaccine development, improved diagnostics, and preventive strategies in high-incidence regions.

发热伴血小板减少综合征患者抗体动态的纵向分析 — 中国高发地区，2010–2023年

闻闫瀚^1*；宋冬梅^2*；李阿茜^1*；孙丽娜¹；马淑花²；刘铁柱¹；黄晓霞¹；黄涛¹；李伯阳¹；王萌璇¹；李建东¹；梁米芳¹；李德新¹；芜为^1#；戴新宪^2#；王世文^1#

1. 传染病溯源预警与智能决策全国重点实验室，国家卫生健康委员会医学病毒学和病毒性疾病重点实验室，中国疾病预防控制中心病毒病预防控制所，北京，中国

2. 国药中生生物技术研究院有限公司，北京，中国。

* 共同第一作者

^# 通信作者：芜为，wuwei@ivdc.chinacdc.cn; 戴新宪，daixinxian@sinopharm.com; 王世文，wangsw@ivdc.chinacdc.cn。

本研究旨在分析中国SFTS高发区2010-2023年间患者的抗体动态（最长发病时间达10年），为疫苗开发、治疗优化和诊断提供支持。对1,233例患者的1,410份血清样本进行纵向分析，检测IgM、IgG和NAb水平，并评估其与病毒载量、临床指标及人群特征的关系。IgM抗体水平在感染后8-14天达峰，180天后几近消失；IgG和NAb抗体水平在22-180天达峰，持续至10年。IgM与病毒载量和多项临床指标相关，死亡病例中水平较低；恢复期老年患者IgG较低，女性高于男性。SFTS患者抗体动态的长期变化揭示了IgM在早期诊断中的价值，IgG和NAb的长期存在显示持久免疫保护，为疫苗开发、诊断改进和防控策略提供科学依据。

For more information: https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2024.244

Phylogeny of Seven Genomes of Monkeypox Virus — Anhui Province, China, 2023

Wanhang Lu¹; Qingqing Chen¹; Xiaomin Wu¹; Jiaqi Li¹; Ming Li¹; Yongkang Xiao¹; Lei Gong¹; Yong Sun^1,#

1. Anhui Provincial Center for Disease Control and Prevention, Hefei City, Anhui Province, China.

# Corresponding author: Yong Sun, biosunyong@163.com.

Monkeypox, first identified in Africa in 1958, is a zoonotic disease caused by monkeypox virus (MPXV). Since January 2022, a global outbreak of mpox has spread to over 100 non-endemic countries. As of June 30, 2024, there have been 99,176 confirmed cases and 535 probable cases across 116 countries, resulting in 208 deaths. This report presents an analysis of the whole genome sequences of seven MPXVs from Anhui Province. We discovered that, compared to the reference sequence (NC_063383.1), these genomes exhibit 91 nucleotide substitutions and 42 amino acid mutations. They are highly similar to genomes of MPXVs that emerged simultaneously in China, Japan, Korea, and Portugal, and are classified within the IIb C.1.1 lineage, with multiple transmission chains and no new branch. The MPXV in Anhui Province has undergone mutations in areas critical for viral replication, transcription, and immune escape, posing a risk of recurrent outbreaks. Therefore, vigilant mutation monitoring of MPXV is imperative.

7株猴痘病毒基因组系统发育分析 — 安徽省，中国，2023年

陆皖行¹；陈晴晴¹；吴小珉¹；李嘉琪¹；李明¹；肖永康¹；龚磊¹；孙永^1,#

1.安徽省疾病预防控制中心，合肥市，安徽省，中国。

^# 通信作者：孙永，sunyong@ahcdc.com.cn。

猴痘是一种由猴痘病毒（MPXV）引起的人畜共患疾病，于1958年在非洲首次发现。自2022年1月以来，猴痘疫情已蔓延到全球100多个非主要流行国家。截至2024年6月30日，116个国家共计报道99176例确诊病例和535例疑似病例，造成208人死亡。本报告对安徽省7株猴痘病毒的全基因组序列进行了分析。我们发现，与参考序列（NC_063383.1）相比，这些病毒基因组共存在91个核苷酸替换和42个氨基酸突变。它们与中国、日本、韩国和葡萄牙同时出现的猴痘病毒基因组高度相似，属于IIb C.1.1谱系，具有多个传播链，没有新的分支。安徽省出现的猴痘病毒在病毒复制、转录和免疫逃逸的关键区域发生了变异，存在再次暴发的风险。因此，对猴痘病毒进行严格的变异监测是极为重要的。

For more information: https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2024.245