Ecology survey of Microtus fortis in natural foci of plague in Dingbian town Shaanxi province in 2010

Objective To investigate the constitution,density changes and carrier rate about Yersinia pestis of rodents in plague foci,and to provide the scientific evidence for plague prevention.Methods According to the program of national monitoring plague,two survey procedures,namely quadrat of single-ha for 24 h and 5 m mouse jam,were used to monitor the host animals; culture and identification of Yersinia pestis in liver or spleen of the experimental animals was carried out by using self-made medium in the north of Beiyuanzi village in Dingbian town Shaanxi province.Results One hundred twelve rodents were captured using the first procedures and the rodent average density was 8.62 ind./hm2 and six species of rodents were found namely Meriones unguiculatus ( 100 individuals),Microtusfortis(5 individuals),Ochotona daurica(3 individuals),Meriones meridianus (2 individuals),Mus musculus Linnaeus (1 individual) and Cricetulus barabensis (1 individual).One hundred seventy-three field mouses were captured using the second procedures including Mus musculus Linnaeus (136 individuals),Cricetulus barabensis (36 individuals),and Microtus fortis ( 1 individual ).Among them,Microtus fortis was found in the salt marshes in the southern edge of Ordos Plateau steppe in plague area of Dingbian county.Yersinia pestis was not identified in all animals.Conclusions Microtus fortis is found in natural foci of plague in Shaanxi province for the first time,and a new geographic region was found.Its epidemiological significance needs further study. Key words: Yersinia pestis ;  Epidemiology;  Microtus fortis