Abstract: Objective To investigate the epidemiological features of hemorrhagic fever with renal syndrome (HFRS), rodent distribution, and the molecular evolutionary characteristics of hantavirus (HV) carried by rodents in Chuxiong, Yunnan province, China. Methods The data of HFRS cases were collected for descriptive epidemiological analysis. The night trapping method was used for rodents, and the composition ratio and density of rodents were calculated. Rodent lungs were collected to detect HV nucleic acid by RT-PCR and to sequence partial fragments of the L gene. Homology and phylogenetic tree analyses were performed using the bioinformatics software ClastalX 1.83 and MEGA 6.0. Results A total of 186 cases of HFRS were reported in Chuxiong from 2015 to 2018, with a mean annual incidence of 7.74/100 000. HFRS occurred in 14 townships of Chuxiong and was mainly epidemic in Lucheng and Donggua towns, which had 75.27% (140/186) of the total cases. There was onset of the disease every month throughout the year. The male-to-female ratio was 2.1:1, and the most cases were young adults and farmers. A total of 1 053 rodents involving 3 species were captured in the residential area of Chuxiong from May to October of 2015-2018; Rattus norvegicus, R. tanezumi, and R. sladeni accounted for 97.06%, 1.80%, and 1.14%, respectively; the densities of the three species were 2.57%, 0.05%, and 0.03%, respectively, with the highest density of 3.09% in Lucheng and Donggua towns. RT-PCR showed that HV nucleic acid was positive in 2 (4.00%; CX04-06 and CX07-09) of 50 lung specimens of R. norvegicus captured in 2016. According to the homology analysis of partial L fragment, the virus strains CX04-06 and CX07-09 were 72.34% to 93.52% homologous in nucleotides to 8 Seoul viruses (SEOV), and had the highest homology (92.39% to 93.52%) to the DLR2 strain of Xiangyun county, Yunnan province and L0199 strain of Laos among the 8 strains, but still with significant differences; they had a low homology to Hantaan virus (69.54% to 71.76%) and Puumala virus (51.19% to 54.44%). Phylogenetic analysis exhibited that the CX04-06 and CX07-09 strains had a close relationship with SEOV reference strains from Xiangyun and Laos. Conclusion There is a high incidence of HFRS in Chuxiong. Rattus norvegicus is the dominant species in the indoor environment of residential areas and carries SEOV, and the epidemic strains show regional characteristics. The rise of HFRS epidemic in Chuxiong is closely related to the widespread distribution and increased population density of R. norvegicus.

Key words: Hemorrhagic fever with renal syndrome, Epidemiological features, Rodent, Hantavirus, Homology analysis, Phylogenetic analysis

摘要： 目的 调查云南省楚雄市肾综合征出血热（HFRS）流行特征、鼠类分布及其携带汉坦病毒（HV）的分子进化特征。方法 收集HFRS病例资料，采用描述流行病学方法进行分析。用笼夜法捕鼠，计算鼠种构成比和鼠密度。鼠肺标本用反转录-聚合酶链式反应（RT-PCR）检测HV核酸及L基因部分片段，并进行序列测定，使用ClastalX 1.83和MEGA 6.0等生物信息学软件进行HV同源性分析和构建系统进化树。结果 2015-2018年楚雄市共报告HFRS病例186例，年平均发病率为7.74/10万。楚雄市14个乡镇均有HFRS病例报告，其中鹿城和东瓜镇发病数占发病总数的75.27%（140/186），为主要流行区。全年各月均有病例发生，男女性别比例为2.1：1，以青壮年和农民居多。2015-2018年的5-10月在楚雄市居住区共捕获鼠类3种1 053只，其中褐家鼠、黄胸鼠和斯氏家鼠的构成比依次为97.06%、1.80%和1.14%，鼠密度依次为2.57%、0.05%和0.03%，以鹿城和东瓜镇褐家鼠密度最高（3.09%）。2016年在楚雄市采获的50只褐家鼠肺脏组织标本经RT-PCR检测，HV核酸阳性2份（CX04-06和CX07-09），带病毒率为4.00%。L基因部分序列同源性分析表明，CX04-06和CX07-09病毒株与8株HV汉城型病毒（SEOV）的核苷酸同源性为72.34%～93.52%，其中，与云南省祥云县DLR2株和老挝L0199株同源性最高（92.39%～93.52%），但仍存在明显差异；与汉滩型病毒和普马拉病毒的核苷酸同源性分别仅为69.54%～71.76%和51.19%～54.44%。系统进化分析表明，CX04-06和CX07-09株与来自云南省祥云县和老挝等地的SEOV参考株具有较近的亲缘关系。结论 楚雄市HFRS高发，褐家鼠为居民区室内优势鼠种并携带SEOV，流行株具有地域特征。楚雄市HFRS疫情上升与褐家鼠广泛分布及其种群密度增高密切相关。

关键词: 肾综合征出血热, 流行特征, 啮齿动物, 汉坦病毒, 同源性分析, 进化分析