We have evaluated the plague epidemic situation in the Three Rivers Source Region,Qinghai Province in recent 20 years to provide the basis for revising the plague prevention countermeasures.We have analyzed the time distribution and the plague epidemic situation between animals and human beings during twenty years in the Three Rivers Source Region,Qinghai Province by describing epidemiology.The animal plague in the natural source of Marmot plague was extremely serious in the Three Rivers Source Region during the past 20 years.It mainly distributes in Yushu State and Tanggula County,Germu City and the serious season ran through the whole period of marmot camp ground activities and the peak was between June and August.Human plague epidemic took place between May and October each year and reached its peak between July and September.The peak covered about 41.67％ at most.It mainly endemic distributes in Nangqian and Xinghai Country.During the past 20 years,we have totally found 14 human plague epidemics in the Three Rivers Source Region,among which 48 cases took place and there were deaths of 17 cases.The fatality rate was 35.42％.The lung type was the majority among 48 cases,which startde with the glandular type.During the past 20 years the plague epidemic has been active and the animal plague epidemic broke out continuously in the Three Rivers Source Region,Qinghai Province.The variety of animals and insects infected the plague epidemic was increasing.The human plague epidemics is most serious with high fatality rate,but it is on the decline as a whole.

Objective To understand the relationship between habitat choice of Himalaya marmot and vegetation elements such as vegetation coverage,grassland type,vegetation type and so on by using geographic information technology in Qinghai.Methods Himalayan marmot field survey data from Qinghai Provincial Institute for Endemic Disease Control and Prevention and vegetation coverage,grassland type and other remote sensing and geographic information data was processed for spatial overlay using ArcGIS tool.The vegetation characteristic information of the location of Himalayan marmot was searched and analyzed statistically,and then the initial quantitative analysis of Himalayan marmot on the selection of habitat vegetation conditions was made.Results After screening,84 samples of Himalayan marmot were retained.The mean of vegetation coverage was 0.708 5,the range was 0.313 3-1.000 0.Totally 54.76％ (46/84) of the Himalayan marmot samples was in the vegetation coverage of 0.70 to 1.00.Among the nine grassland types,the alpine meadows accounted for 39.78％ of total area of Qinghai,with 59 Himalayan marmot sample points distributed,which accounting for 70.24％ (59/84).Himalayan marmot mainly feed on some of the roots of grassland plants,including Poa pratensis,Alpine Kobresia,Potentilla,Polygonum viviparum,Kobresia cordata,Oxytropis,Aster and other miscellaneous grass.Conclusions Vegetation conditions is one of the important factors of Himalayan marmot in habitat selection.Quantitative analysis of the relationship between Himalayan marmot spatial distribution and vegetation factors by using geographic information technology,can deepen the understanding of marmot habitat selection,and provide a basis for grassland plague surveillance and control.

Objective:To investigate the contents of soil metal elements in the plague high incidence area and resting area in the plague natural foci of Qingnan region in Qinghai Province, and to compare and analyze the differences of the contents of soil metal elements between the two areas.Methods:A total of 69 soil samples were collected from 11 sites in the plague high incidence area (Yushu Prefecture) and resting area (Guoluo Prefecture) in Qingnan region, including 39 samples from high incidence area and 30 samples from resting area. The contents of 12 soil metal elements, such as iron (Fe), magnesium (Mg), calcium (Ca), barium (Ba), cobalt (Co), copper (Cu), manganese (Mn), lead (Pb), rubidium (Rb), titanium (Ti), vanadium (V) and zinc (Zn), were measured by X-ray fluorescence spectrometry and SPSS 20.0 software was used for Spearman correlation and other statistical analysis.Results:The contents of Fe and Ca in the soil of the plague natural foci of Qingnan region were relatively high. The contents of 12 soil metal elements in the high incidence area were significantly higher than those in the resting area ( P < 0.01 or < 0.05). There were statistical significant differences in the contents of Mg, Ca, Ba, Mn, Pb and Zn in the soil among the sample plots of the plague high incidence area ( P < 0.01 or < 0.05). There were statistical significant differences in the contents of Fe, Mg, Ca, Rb and Ti in the soil among the sample plots of the plague resting area ( P < 0.05 or < 0.01). Except for Mg and Ca, Fe was positively correlated with other metal elements in the high incidence area and resting area ( P < 0.01 or < 0.05), and Fe was strongly positively correlated with Rb, Ti and V ( r = 0.780 - 0.838). Mg was only positively correlated with Ca in the high incidence area and resting area ( P < 0.01). Ca was negatively correlated with Mn, Pb, Rb, Ti, V and Zn in the high incidence area, and with Rb and Zn in the resting area ( P < 0.01 or < 0.05). The rest of the metal elements were mostly positively correlated in the high incidence area and resting area. Conclusions:The contents of Fe and Ca are rich in the plague natural foci of Qingnan region in Qinghai Province. There are correlations among most soil metal elements in the high incidence area and resting area. The correlation between the contents of soil metal elements in the plague natural foci and the epidemic of plague is worth further exploring.