Objective To analyze the epidemic characteristics of plague epidemics, host and vector community structure, and abundance in plague focus of wild rodents in Yunnan Province, 2017-2023, providing a scientific basis for formulating plague prevention strategies and forecasting warning for this epidemic foci. Methods　Following the requirements of the "National Plague Surveillance Plan" and the "Yunnan Provincial Plague Surveillance Plan", host-vector surveillance, etiology, and serological testing were carried out, and plague epidemic data and host-vector surveillance data in plague focus of wild rodents in Yunnan Province, 2017-2023 were collected and sorted using Excel 2019 software to create a database for descriptive analysis. Results From 2017 to 2023, 11 animal plague epidemics were discovered in the wild plague foci of Yunnan Province, with 18 epidemic spots. From the altitude distribution point of view, 7 epidemic spots were distributed at an altitude of 2 800-3 000 meters, another seven at 3 000 and 3 200 meters, and four spots were located in areas with an altitude of ≥3 200 meters; a total of 36 samples of host and vector animals were detected positive, including 28 positive samples of host animals and 8 positive samples of vector animals, and 29 strains of Yersinia pestis were isolated; in terms of species composition, Eothenomys miletus accounted for the largest proportion of 41.67%, followed by Apodemus chevrieri at 22.22%; Ctenophthalmus quadratus at 11.11%; Rattus tanezumi and Neopsylla specialis each at 8.33%, and Dremomys pernyi, rat carcass, and Frontopsyllas padix each accounted for 2.78%; the epidemic peaked in April, and no human cases were found. A total of 453 220 rat cages (traps) were placed, capturing 27 677 rodents, with an average capture rate of 6.11%. A total of 25 075 main hosts, Apodemus chevrieri and Eothenomys miletus, were captured, accounting for 90.60% of the total capture rate. A total of 14 700 fleas were seized on the surface of small animals, with a total flea infection rate of 23.13% and a flea index of 0.59. The main vectors were Ctenophthalmus quadratus and Neopsylla specialis, with constituting ratios of 45.71% and 22.69%, respectively. Conclusions From 2017 to 2023, the population density of main host animals in Yunnan's wild rodent plague foci was relatively high and showed an upward trend, possibly related to the local planting structures. Plague plays a regulatory role in host population structures. Epidemics among animals showed obvious seasonality, with a trend of expanding epidemic areas. No human cases were found, but Yersinia pestis was detected in Rattus tanezumi in human settlements, raising the possibility that animal plague could spread to humans. It suggests strengthening the monitoring of areas adjacent to the epidemic source, eradicating rats and fleas in spring, improving the accuracy of plague prediction and early warning, providing strong technical support for the early detection of plague among animals, and preventing the spread of the epidemic to humans.

ObjectiveTo analyze the community structure and dynamics of parasitic fleas on the body surface of host animals and nested fleas in different seasons in the natural foci of wild rat plague in Yulong County，Yunnan Province， to explore the relationship between seasonal fluctuation of fleas and the prevalence of plague among animals， so as to provide evidence for plague prevention and control in the natural foci. MethodsNanxi Village， Huangshan Town， the core area of plague epidemic in Yulong County， was selected as the monitoring sample area in December 2019 （winter）， August 2020（summer）， October 2020（autumn） and March 2021（spring）. Host animals were captured by rattrap at night and rat nests were excavated for collecting parasitic fleas on host animals and rat nest fleas in different seasons. Excel 2010 and SPSS 26.0 software were used to analyze the data， and Chi square test was used to compare the rate. Community ecological indicators were used to analyze the community structure and species diversity of the host animals and their parasitic fleas. ResultsA total of 355 vector fleas were captured， belonging to 7 species of 5 genera in 2 families. 441 small animals were captured and 138 rat body fleas were detected with the flea infection rate of 14.51% and the flea index 0.31. 96 effective rat holes were excavated and 217 fleas were detected with the flea infection rate of 35.42% and the flea index 2.26. Among the four seasons， the flea infection rates of rat body and rat nests were higher in summer and winter， showing a significant difference in general （χ²=15.851， P<0.01； χ²=16.398， P<0.01）. The dominant species of flea community were Ctenophthalmus quadratus， Stenischia humilis， Neopsylla specialis and Frontopsylla spadix， with a dominance index of 0.434， 0.254， 0.180 and 0.110， respectively. The diversity and evenness of rat body fleas showed a distribution characteristic of decreasing， increasing and then decreasing again with season changes， and both were the highest in spring， while the ecological dominance showed an opposite trend. The diversity and evenness of rat nest fleas showed a distribution characteristic of increasing first and then decreasing in summer， autumn and winter， with the highest in autumn， while the ecological dominance was diametrically opposite. ConclusionThe fleas community structure is relatively stable in Yulong County， but the number of species in the community is unevenly distributed by seasons， and the status of dominant species is prominent. Local authorities should carry out timely preventive deratization and depulization measures according to the results of daily monitoring， so as to effectively avoid the prevalence and spread of plague among animals in plague foci.