A retrospective analysis of plague in Three-River Source Region of Qinghai from 1954 to 2007

Objective To analyze plague epidemic tendency in the Three-River Region of Qinghai.Methods Using retrospective study,the Three-River Region during 1954-2006 year pestis epidemic focus were investigated and analyzed.Result Pestis prevailed mainly in Yushu,Chindu,Qumalai,Nangqian,Zhiduo and the Geermu.Tanghla Township.It was first found that the nature plague focus of miefitus existed in Chengduo County.There are 1 5 kinds of 12 branches in 8 trees infected plague animals were founded,336 Yersinia pestis were separated from the driven objects.Among them there were 291 Himalayas marmot body,account for 86.60%of the total,13 of Tibet sheep,accounts for 3.87%.10 of Qinghai field-mouse,accounts for 2.98%,Also there were 114 Yersinia pestis which were separated from each kind of vector insect in vivo.And,46 pestis strains came from the axe shape of flea in vivo account for 40.35%(46/114),38 pestis strains separated from Xie mountain flea,account for 33.33% (38/114).During 1960-2006 years there were 85 human plague cases were founded,238 occurred,134 died,the case fatality rate wero 56.30%(134/238),the popular seasons were started from May to November,the peak season happened in Aug and Sep.After Oct mainly due to Tibet sheep pestis which will cause as the origin of infection.The majority of sickness was pulmonary plague,account for 49.58%(117/238),whereas the first round case caused by the gland bubonic plague,account for 77.12%(91/118).Conclusions There are two pestis strains natural epidemic focus places in Three-River Source Region of Qinghai including the Himalayas marmot pestis strain and the Qinghai field-mouse pestis strain.The case of human pestis strain causes by the marmot strain,the fiehl-mouse mold mushroom spawn causes human pestis strain has not yet discovered,Three-River Source Region of Qinghai is a pestis strain key popular area in Qinghai Province. Key words: Yeminia pestis; Epidemiology; Three-River Source Region