title: Mapping risk of plague in Qinghai-Tibetan Plateau, China.
abstract: BACKGROUND
  Qinghai-Tibetan Plateau of China is known to be the plague endemic region where marmot (Marmota himalayana) is the primary host. Human plague cases are relatively low incidence but high mortality, which presents unique surveillance and public health challenges, because early detection through surveillance may not always be feasible and infrequent clinical cases may be misdiagnosed.
  
  
  METHODS
  Based on plague surveillance data and environmental variables, Maxent was applied to model the presence probability of plague host. 75% occurrence points were randomly selected for training model, and the rest 25% points were used for model test and validation. Maxent model performance was measured as test gain and test AUC. The optimal probability cut-off value was chosen by maximizing training sensitivity and specificity simultaneously.
  
  
  RESULTS
  We used field surveillance data in an ecological niche modeling (ENM) framework to depict spatial distribution of natural foci of plague in Qinghai-Tibetan Plateau. Most human-inhabited areas at risk of exposure to enzootic plague are distributed in the east and south of the Plateau. Elevation, temperature of land surface and normalized difference vegetation index play a large part in determining the distribution of the enzootic plague.
  
  
  CONCLUSIONS
  This study provided a more detailed view of spatial pattern of enzootic plague and human-inhabited areas at risk of plague. The maps could help public health authorities decide where to perform plague surveillance and take preventive measures in Qinghai-Tibetan Plateau.
authors.forename: Quan
authors.initials: Q
authors.lastname: Qian
authors.forename: Jian
authors.initials: J
authors.lastname: Zhao
authors.forename: Liqun
authors.initials: L
authors.lastname: Fang
authors.forename: Hang
authors.initials: H
authors.lastname: Zhou
authors.forename: Wenyi
authors.initials: W
authors.lastname: Zhang
authors.forename: Lan
authors.initials: L
authors.lastname: Wei
authors.forename: Hong
authors.initials: H
authors.lastname: Yang
authors.forename: Wenwu
authors.initials: W
authors.lastname: Yin
authors.forename: Wuchun
authors.initials: W
authors.lastname: Cao
authors.affiliation: Chinese Center for Disease Control and Prevention, Beijing, China. liqun@chinacdc.cn.
authors.forename: Qun
authors.initials: Q
authors.lastname: Li
mesh_terms: D006801:Humans; D015233:Models, Statistical; D010930:Plague / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D011159:Population Surveillance; D012307:Risk Factors; D018609:Tibet / Q000453:epidemiology