Abstract: Objective To analyze the changes in the species and densities of the hosts and vectors of plague in Yuxi, Yunnan province, China, with understanding its epidemic pattern, and to provide scientific evidence for preventing and controlling plague. Methods According to the National Plague Surveillance Protocol and Yunnan Provincial Plague Surveillance Protocol, we collected the surveillance data of the hosts, vectors, pathogeny, and serology from seven counties and two districts of Yuxi from 1985 to 2018. We calculated the densities of plague hosts, rate of flea infestation, and flea index by Excel 2010 software, and estimated the Pearson correlation coefficient between Rattus tanezumi density and Xenopsylla cheopis by R3.5.1 software. Results There were two human plague outbreaks in Yuxi, 1985-2018, involving 11 confirmed cases of bubonic plague (9 cases in Yuanjiang county and 2 cases in Xinping county). A total of 59 331 myomorphous rodents were captured, involving 21 species of 13 genera of 6 families of 3 orders, and the overall capture rate was 3.78% (95% confidence interval:3.75%-3.81%). The dominant species was R. norvegicus, accounting for 57.80% of the total number. A total of 55 137 parasitic fleas were collected, involving 8 species of 8 genera of 5 subfamilies of 4 families. The rate of flea infestation was 28.36%, and the overall flea index was 0.83. The dominant species was X. cheopis, accounting for 46.32% of the total number. Indirect hemagglutination assay detected 11 positive serum samples out of 35 412 samples from host animals, and yielded 100% positive results for 11 serum samples of suspected plague patients. Reverse indirect hemagglutination assay detected 4 out of 7 organ samples from rodent. Four strains of Yersinia pestis were isolated from 89 968 host animals examined, and the test was negative for all 33 028 fleas examined. There was no significant association of R. tanezumi density and X. cheopis (r=-0.09, P=0.658). Conclusion During the recent twenty years, the species and densities of plague hosts and vectors were kept at relatively stable levels, and plague was in a relatively silent period in its epidemic foci. However, the main host R. tanezumi and the main vector X. cheopis are still maintained in a certain number, demanding strengthened plague surveillance and improved surveillance quality for timely detection and prevention of the occurrence and spread of human plague.

Key words: Plague, Host, Vector, Surveillance

摘要： 目的 分析云南省玉溪市鼠疫宿主动物、媒介种类和密度变化趋势，掌握鼠疫流行规律，为鼠疫防控提供科学依据。方法 按照《全国鼠疫监测方案》和《云南省鼠疫监测方案》，收集整理1985-2018年玉溪市7县2区鼠疫宿主、媒介、病原学和血清学监测资料，采用Excel 2010软件计算鼠疫宿主动物密度、染蚤率和蚤指数等，在R3.5.1软件中使用Pearson相关系数探索黄胸鼠密度与印鼠客蚤的关系。结果 1985-2018年玉溪市共发生人间鼠疫疫情2起，确诊腺鼠疫病例11例（元江县9例，新平县2例）；共捕获鼠形动物59 331只，隶属于3目6科13属21种，总捕获率为3.78%（95% CI：3.75%~3.81%），褐家鼠为优势鼠种，占捕获总数的57.80%；共捡获寄生蚤55 137匹，隶属于4科5亚科8属8种，染蚤率为28.36%，总蚤指数为0.83，印鼠客蚤为优势蚤种，占获蚤总数的46.32%；应用间接血凝试验检测宿主动物血清35 412份，阳性11份；检测疑似鼠疫患者血清11份，均为阳性；应用反向间接血凝试验检测鼠类脏器标本7份，阳性4份；检验宿主动物89 968只，分离鼠疫耶尔森菌4株；检验媒介蚤类33 028匹，结果均为阴性。黄胸鼠密度和印鼠客蚤无显著相关关系（r=-0.09，P=0.658）。结论 近20多年来玉溪市鼠疫宿主、媒介种类和密度保持相对稳定，疫源地处于静息期。鼠疫主要宿主黄胸鼠和主要传播媒介印鼠客蚤仍保持一定数量，需加强鼠疫监测，提高监测质量，及时发现疫情，以防止人间鼠疫疫情的发生和流行。

关键词: 鼠疫, 宿主, 媒介, 监测