Survey on rats and parasitical fleas in historical plague focus in Dongyang of Zhejiang,2007 - 2009

Objective To understand the species and distribution of rats and parasitical fleas in historical plague focus in Dongyang, and provide evidence for plague prevention and control. Methods Cages were used at night to capture rats, the types of the rats and fleas were identified, and the infection rate of rats and flea index were calculated. Indirect hemorrhagic assay (IHA) was used to test the plague F1 antibody. Four-step testing was used in etiological examination. Results A total of 1897 rats were captured, which belonged to 11 species in 7 genus in 3 families of 2 orders. Eothenomys melanogaster accounted for 72.43% of the wild rats (1306/1803), Rattus norvegicus accounted for 59.57% of the indoor rats (56/94). Up to 1773 live rats were tested. The flea infection rate of rats was 1.13%, with the total flea index of 0.012, Monopsyllus and anisus accounted for 68.18% (15/22). Up to 1859 serum specimens were examined, all were negative.1525 specimens were used in etiological examination, no strain of Yersinia pestis was isolated. Conclusion Rattus norvegicus and Eothenomys melanogaster were the predominant species of the rats. No Xenopsylla cheopis was found, both the flea infection rate and total flea index were lower than the control level of plague and no positive results were obtained in plague F1 antibody test and etiological examination, which indicated that the plague in rats is still in silent period.