The etiological research and epidemiological significance of Yersinia pestis separated from Tibetan sheep in Yushu City, Qinghai Province

Objective To discuss the biological characteristics and epidemiological significance of Yersinia pestis separated from Tibetan sheep in Yushu City, Qinghai Province, in order to provide scientific basis for plague prevention and control in this area. Methods Ten strains separated from Tibetan sheep in Yushu City, Qinghai Province from 1975 to 2005 were selected to do biochemical test, toxicity test, virulence factors evaluation, plasmid analysis and different region genotyping (DFR). Results All the strains' biovars were antique, 9 strains were Qinghai-Tibet Plateau ecotype and the other one was Qilian Mountains ecotype. The strains' genotype was genomovar 5. All the strains' plasmid spectrum were the same as -6 × 106, 45 × 106, 65 × 106. Fifty percent (5/10) strains contained all the four virulence factors. Toxicity test showed these strains were velogenic. Conclusions Strains separated from Tibetan sheep in Yushu City, Qinghai Province have the characteristics of Qinghai-Tibet plateau plague's pathogen. Tibetan sheep plague is still a potential threat to people's health and economic development. So we have to enhance the plague monitoring and related health education. Key words: Plague; Tibetan sheep; Etiology; Epidemiology