Plague surveillance and risk analysis in Menglian County,Yunnan Province,2016-2020
Objective To understand the population composition and quantitative changes of plague hosts and vectors in Menglian County,Yunnan Province,to monitor and investigate the epidemic dynamics of plague,and to evaluate the epidemic risk of plague,providing a scientific basis for plague prevention and control in Yunnan's border areas.Methods Animal plague surveillance was carried out according to the"Yunnan Provincial Plague Surveillance Program",and the data of plague surveillance in Menglian County from 2016 to 2020 were collected and analyzed.In 2020,a plague survey was conducted in two border towns in Menglian County.The samples of host animals and their surface parasitic fleas in residential,agricultural,and forest areas were collected,and serum samples of border residents and plague indicator animals were collected.Yersinia pestis was isolated and cultured from host animal organs and flea samples,and indirect hemagglutination assay(IHA)was used to detect F1 antibody in serum samples.Results A total of 793 host animals,encompassing 11 species across 7 genera and 4 families in 3 orders,were captured in animal plague surveillance in Menglian County,from 2016 to 2020.Rattus tanezumi was identified as the dominant indoor and outdoor species,with composition ratios of 93.58%and 83.91%,respectively.Suncus murinus,Rattus nitidus,Tupaia belangeri,and Rattus andamanensis were common species.The average rodent density indoors and outdoors was 1.33%and 1.65%,respectively.In 2020,the special survey in Menglian County's border areas captured 313 host animals,including 15 species across 9 genera and 4 families in 3 orders.The dominant species were Rattus tanezumi,Rattus andamanensis,and Suncus murinus,with composition ratios of 47.60%,20.13%,and 10.86%,respectively.The capture rates of indoor and outdoor host animals were 3.25%and 18.81%,respectively.There were statistically significant differences in the capture rates of indoor and outdoor host animals and the density of indoor and outdoor Rattus tanezumi between routine monitoring and special investigation(χ2=30.682,1641.931,32.690,320.415,P<0.001).From 2016 to 2020,the flea infection rate of Xenopsylla cheopis on Rattus tanezumi was 30.97%,with a flea index of 0.79.In the 2020 special survey in Menglian County's border areas,a total of 99 fleas were captured across 7 species,7 genera,and 4 families,with Xenopsylla cheopis and Palaeopsylla remota as the dominant ectoparasitic flea species,having composition ratios of 69.70%and 20.20%,and an infection rate of 9.90%.The infection rate of Xenopsylla cheopis on the surface of Rattus tanezumi was 12.08%(18/149),with a flea index of 0.46.There was a significant difference in the infection rate of Xenopsylla cheopis on the surface of Rattus tanezumi between routine monitoring and special investigation(χ2=22.773,P<0.001).Laboratory test results from both routine monitoring and special investigation were negative.Conclusions The primary species of the main hosts and vectors of plague in Menglian County are prominent,and the density of rodents in the outdoor environment is relatively high.The monitoring and investigation did not find the infection of residents and animals in recent years.However,given the localized low-grade plague endemics in the surrounding areas,it is necessary to continuously strengthen the professional and technical training at the grass-roots level and enhance the monitoring and investigation of plague and other rodent-borne diseases in the border areas to effectively improve the quality and sensitivity of monitoring,timely carry out preventive prevention and control measures,effectively detect the epidemic,and reduce the risk of epidemic.
万方数据
