EN
The objective of the study was to establish possibilities of the development of the I stage larvae of E. cervi in fishes and amphibians, and possibilities of paratheny in the organism of these animals. In the alimentary tract of the fishes both the I stage and the invasive (i.e. III stage) larvae can not cross the intestine barrier and undergo digestion. However, in the frag organism the I stage larvae of E. cervi are capable of crossing the wall of the alimentary canal and of going through a part of their development, though not attaining the II stage. The invasive larvae fed to the frogs penetrate under the peritoneum, into the mesenterium and the muscles and there they survive inside cysts. Frogs as parathenic hosts for E. cervi can be dangerous for predators feeding on amphibians. The larvae of E. cervi liberated in their organism can pass through the cerebral phase of their development thus causing neural clinical symptoms.