Cross sectional survey in historical epidemic focus of plague in Qingyuan, Zhejiang province

Objective To conduct basic epidemiological survey in historical epidemic focus of plague in Qingyuan county and provide evidence for the effective prevention and control of plague. Methods Field survey was conducted on the distribution and density/proportion of host animals and vectors of plague (rat and flea), the etiological analysis and serological analysis were conducted and climate and environment factors were analyzed. Results The predominant indoor rat species were Rattus norvegicus, Rattus flavipectus and Mus musculus, their densities were 2.57%, 1.54% and 0.07%, respectively. The predominant outdoor rat species were Rattus losea, Apodemus agrarius and Microtus fortis, their densities were 4.67%, 0.74% and 0.62% respectively. The main vectors were Asiatic ratflea (40.33%), Leptopsylla musculi (28.85%) and Ceratophyllus anisus (25.57%). The infection rate in flea was 9.82% and flea index was 0.28. The etiological and serological detections for plague pathogen were all negative. Conclusion The climate and environment in Qingyuan suits the breeding of plague host animals and vectors. Although it is silent period of plague, the density of major host animal-Rattus flavipectus and the index of major vector-Asiatic rat flea were high, multi changes in natural focus of plague have been observed and new bio-transmission chain might be established, the natural focus of plague might re-emerge. It is necessary to pay close attention and conduct further study on the possibility of re-merging of natural focus of plague.