云南省玉龙鼠疫疫源地野外鼠形动物寄生蚤丰盛度影响因素分析

【目的】分析云南省玉龙鼠疫疫源地野外鼠形动物寄生蚤丰盛度的影响因素。【方法】选取云南省玉龙鼠疫疫源地3个海拔区域，按4个季节进行野外捕鼠，捕获的鼠形动物用梳检法收集体表寄生蚤并在显微镜下分类鉴定。通过实际测量和实地观察相结合的方式收集潜在影响鼠形动物寄生蚤丰盛度的因素包括鼠形动物特征变量指标(如种类、年龄、性别、体长、体重)、环境和气象因子(如海拔、季节)等数据。采用EpiData 3.02软件建立数据库，在R软件下使用跨栏负二项分布回归分析鼠形动物寄生蚤丰盛度的影响因素。【结果】从捕获的884只鼠形动物中检获寄生蚤9种484头，以特新蚤指名亚种、方叶栉眼蚤、无值大锥蚤、云南栉眼蚤为主(86.16%)。回归分析显示： 2 700-3 000 m和3 000 m以上海拔鼠形动物染蚤概率较2 400-2 700 m分别增加1.27和3.72倍；湿度高于70%时，鼠形动物染蚤概率较湿度≤70%时减少41%；与齐氏姬鼠的染蚤概率相比，中华姬鼠的染蚤概率降低50%，大绒鼠的染蚤概率增加79%；体长超过104 mm的鼠形动物染蚤概率较体长≤104 mm的鼠形动物染蚤概率增加76%；气温高于15℃时，鼠形动物染蚤数量较温度≤15℃时降低67%；成年鼠形动物的染蚤数量较未成年鼠形动物的染蚤数量增加2.25倍；与春季相比，夏季的染蚤数量增加2.00倍，秋季的染蚤概率减少48%，冬季的染蚤概率和染蚤数量分别增加1.44和1.06倍。【结论】玉龙鼠疫疫源地野外鼠形动物寄生蚤以特新蚤指名亚种、方叶栉眼蚤、无值大锥蚤、云南栉眼蚤为优势蚤种。鼠形动物寄生蚤丰盛度与海拔、季节、气温、湿度等环境气象因子及鼠形动物种类、体长、年龄等鼠形动物特征变量密切相关。

Analysis of factors affecting the abundance of parasitic fleas on wild myomorph rodents in the Yulong plague focus of Yunnan Province,southwestern China

【Aim】 To analyze the predictors of the abundance of parasitic fleas on wild myomorph rodents in the Yulong plague focus of Yunnan Province, southwestern China. 【Methods】 Field rodent trapping was carried out in three altitudes and four seasons of plague foci in Yulong County, Yunnan Province. The parasitic fleas on myomorph rodents were collected by comb method and identified under a microscope. Data of potential predictors of the abundance of parasitic fleas, including characters of myomorph rodents (such as species, age, gender, body length, and weight) and environmental factors (such as altitude and season), were collected through measurement and observation. Data set was established using EpiData 3.0.2. The relationship between the abundance of parasitic fleas and the potential predictors was explored using hurdle negative binomial regression model under R software. 【Results】 A total of 484 parasitic fleas belonging to nine species were collected from 884 myomorph rodents. Among them, Neopsylla specialis specialis, Ctenophthalmus quadrates, Macrostylophora euteles and Ctenophthalmus yunnanus fleas are dominant, with their individual number accounting for 86.16% of the total number of individuals of fleas. Regression analysis revealed that the probability of flea infestation at 2 700-3 000 m and above 3 000 m increased by 1.27 and 3.72 times as compared with that at 2 400-2 700 m, respectively. The probability of flea infestation under the humidity over 70% decreased by 41% as compared with that under the humidity not exceeding 70%. The probability of flea infestation on Apodemus draco reduced by 50% as compared with that on Apodemus chevrieri, while the probability of flea infestation on Eothenomys miletus increased by 79%. The probability of flea infestation on myomorph rodents with the body length exceeding 104 mm increased by 76% as compared with that on myomorph rodents with the body length less than or equal to 104 mm. When air temperature exceeded 15℃, the number of fleas on myomorph rodents decreased by 67% as compared with that at the air temperature not exceeding 15℃. The number of fleas on adult myomorph rodents increased by 2.25 times as compared with that of immature myomorph rodents. The number of fleas in summer increased by 2.00 times, the probability of flea infestation in autumn decreased by 48%, and the probability of flea infestation and the number of fleas in winter increased by 1.44 and 1.06 times, respectively, as compared with those in spring. 【Conclusion】 Neopsylla specialis specialis, Ctenophthalmus quadrates, Macrostylophora euteles and Ctenophthalmus yunnanus are the dominant species of parasitic fleas on wild myomorph rodents in the Yulong plague focus. The abundance of parasitic fleas is closely related to the environmental factors such as altitude, season, air temperature and humidity, and the characters of myomorph rodents such as species, body length, and age.