Sylvatic echinococcosis in Argentina. II. Susceptibility of wild carnivores to Echinococcus granulosus (Batsch, 1786) and host-induced morphological variation.

Domestic dogs and cats, 3 fox species, Dusicyon culpaeus (Molina,1782), D, griseus (Gray, 1837) and D. gymnocercus (Thomas, 1914), Geoffroy's cats, Felis geoffroyi (D'Orbigny and Gervais, 1843), and grisons, Galictus cuja (Molina, 1782) were fed larvae of Echinococcus granulosus (Batsch, 1786) from domestic sheep in Argentina. Dogs and the 3 species of foxes became infected. The susceptibility of D. culpaeus compared favorably to that of dogs. Most D. griseus and D. gymnocercus were less susceptible than dogs but gravid strobilae were recovered from some animals of both species. Eggs from strobilae in dogs and Dusicyon spp. were infective to CF1 mice. The mean strobilar length and the diameters of the rostellar pad and suckers of worms in foxes were significantly reduced when compared with previously reported data for strobilae from dogs. The potential significance of Dusicyon spp. as reservoir hosts of E. granulosus in Argentina is discussed as is the confusion surrounding the taxonomic identification of cestode infections previously reported from these wild carnivores. It is suggested that Echinococcus spp. reported from Argentine foxes are E. granulosus and that foxes become infected by killing and scavenging on sheep in localities where E. granulosus is endemic.