Surveillance of rodent density and Yersinia pestis in Longquan from 2014 to 2023

TIAN Zhi; HONG Hao; LI Wenhao; JI Xinxing; WANG Junhu; QIAO Mengling; JIA Desheng

doi:10.19821/j.1671-2781.2025.04.012

Abstract：Objective To analyze the plague surveillance data in Longquan and clarify the local rodent population density and distribution of Yersinia pestis.Methods Surveillance data on plague from 2014 to 2023 were collected,and the distribution characteristics of plague related animals,vectors and Y.pestis were analyzed by using descriptive epidemiological statistical methods.Chi-square test was used to compare differences in rodent density among different years,and Cochran Armitage trend test was employed to assess time trends in rodent density.Results From 2014 to 2023,a total of 2 034 rodents were captured,with an overall rodent density of 3.20%.Among them,the indoor rodent density was 1.64%,showing a significant downward trend(Z=4.636,P＜0.001)in these years.The rodent density of main species,Rattus norvegicus,showed no statistical differences in different years(Z=-1.559,P=0.119),while Mus musculus and R.tanezumi exhibited decreasing trends(Z=9.479,P＜0.001;Z=9.217,P＜0.001).Outdoor rodent density was 5.67%,also demonstrating a downward trend(Z=2.961,P=0.030).Apodemus agrarius,the main outdoor species,showed a decreasing trend(Z=2.769,P=0.006),whereas the density of R.losea and Microtus fortis showed no statistical differences in different years(Z=1.664,P=0.096;Z=0.904,P=0.366).Indoor rodent density exhibited a bimodal distribution from March to November,while outdoor rodent density showed a unimodal distribution.Different rodent species displayed varying seasonal fluctuation patterns.Additionally,19 fleas were detected,with a flea index of 0.01 and a flea infestation rate of 0.79%.Testing of 2 034 serum samples revealed no positive results for F1 antibody against Y.pestis.Furthermore,no Y.pestis was detected after isolating and culturing 2 053 samples.Conclusion The plague epidemic among animals in Longquan is currently in a quiescent phase,but the risk of plague outbreaks still exists.Therefore,it remains necessary to strengthen plague surveillance and promote rodent control measures.