title: Impact of overgrazing on the transmission of Echinococcus multilocularis in Tibetan pastoral communities of Sichuan Province, China.
abstract: BACKGROUND
  Overgrazing was assumed to increase the population density of small mammals that are the intermediate hosts of Echinococcus multilocularis, the pathogen of alveolar echinococcosis in the Qinghai Tibet Plateau. This research tested the hypothesis that overgrazing might promote Echinococcus multilocularis transmission through increasing populations of small mammal, intermediate hosts in Tibetan pastoral communities.
  
  
  METHODS
  Grazing practices, small mammal indices and dog Echinococcus multilocularis infection data were collected to analyze the relation between overgrazing and Echinococcus multilocularis transmission using nonparametric tests and multiple stepwise logistic regression.
  
  
  RESULTS
  In the investigated area, raising livestock was a key industry. The communal pastures existed and the available forage was deficient for grazing. Open (common) pastures were overgrazed and had higher burrow density of small mammals compared with neighboring fenced (private) pastures; this high overgrazing pressure on the open pastures measured by neighboring fenced area led to higher burrow density of small mammals in open pastures. The median burrow density of small mammals in open pastures was independently associated with nearby canine Echinococcus multilocularis infection (P = 0.003, OR = 1.048).
  
  
  CONCLUSIONS
  Overgrazing may promote the transmission of Echinococcus multilocularis through increasing the population density of small mammals.
authors.affiliation: Sichuan Centre for Disease Control and Prevention, Chengdu 610041, China. wangqian67@yahoo.com.cn
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.forename: Yong-fu
authors.initials: YF
authors.lastname: Xiao
authors.forename: Dominique A
authors.initials: DA
authors.lastname: Vuitton
authors.forename: Peter M
authors.initials: PM
authors.lastname: Schantz
authors.forename: Francis
authors.initials: F
authors.lastname: Raoul
authors.forename: Christine
authors.initials: C
authors.lastname: Budke
authors.forename: Maiza
authors.initials: M
authors.lastname: Campos-Ponce
authors.forename: Philip S
authors.initials: PS
authors.lastname: Craig
authors.forename: Patrick
authors.initials: P
authors.lastname: Giraudoux
mesh_terms: D000818:Animals; D004283:Dog Diseases / Q000635:transmission*; D004285:Dogs; D004443:Echinococcosis / Q000635:transmission* / Q000662:veterinary; D048210:Echinococcus multilocularis; D006801:Humans; D011156:Population Density; D018609:Tibet