Studies on native small mammals as intermediate hosts of Echinococcus multilocularis

A field survey to determine the intermediate host(s) of Echinococcus multilocularis in southwestern Montana involved the examination of 1,245 small mammals representing 17 species.Two naturally infected muskrats (Ondatra zibethicus) were collected from the East Gallatin River in Gallatin County during the winter of 1980.No other species were found to be infected with this larval cestode.Fifty-eight experimental inoculations of 5 species of rodents and 1`lagomorph by feeding ova induced fertile cyst development in one deer mouse (Peromyscus maniculatus) and one muskrat.Successful culturing of the Montana isolate by intra-peritoneal inoculation of cyst material occurred in 4 of 11 cotton rats (Sigmodon hispidus).Nineteen deer mice were refractory to infection via intraperitoneal injection.Additionally, data on the occurrence of 3 metazoan liver parasites in Montana small mammals is included.