Impact of overgrazing on the transmission of Echinococcus multilocularis in Tibetan pastoral communities of Sichuan Province, China.
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.
Wang
Qian
Q
Sichuan Centre for Disease Control and Prevention, Chengdu 610041, China. wangqian67@yahoo.com.cn
Xiao
Yong-fu
YF
Vuitton
Dominique A
DA
Schantz
Peter M
PM
Raoul
Francis
F
Budke
Christine
C
Campos-Ponce
Maiza
M
Craig
Philip S
PS
Giraudoux
Patrick
P
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