Abstract
Relationships between the prevalence of alveolar hydatid (Echinococcus muitilocularis) in red foxes (Vulpes vulpes) captured in 74 regions of Hokkaido, Japan from 1985 to 1990 and some regional environmental factors (including population density of voles, temperature, snowfall depth, mean degree of slope, mean altitude, human population density, etc.) were examined using simple and multiple regression analysis methods. Eight explanatory variables were selected from 15 types of candidate variables belonging to eight respective categories of the regional environmental factors, based on the simple regression analysis. In the multiple regression analysis, only two of these eight explanatory variables were selected with a stepwise process, and the following model was obtained: Y=0.00979X_1-0.00037X_2+0.23833 (Y: arcsin-root transformed prevalence of E. multilocularis in foxes, X_1: captive number of voles in September, X_2: number of days with snowfall deeper than 50 cm, r=0.32180, P=0.0001). The higher density of the voles is supposed to make the establishment of the life cycle of this cestode species more successful. The negative influence of deeper snowfall on the prevalence is attributable to the lower predation pressure on the voles by the foxes in deeper snowfall, which suppresses the hunting behavior of the foxes.
