Paratenic host

A paratenic host (from the Greek parateinein = to delay) is a host organism or host species in which a parasite (or parasite) is not able to develop significantly and which is dispensable for the actual life cycle of the parasite. For example, predatory fish (pike) for Plerocercoid of the tapeworm Diphyllobothrium (the actual intermediate host is the carp).

The actual intermediate hosts for Diphyllobothrium latum (fish tapeworm) are copepods of the genera Diaptomus and Cyclops. The procercoid matures in the crawfish. The oar crustaceans are taken up by carp fish as food. There the parasites then penetrate the intestinal wall of the fish and thus develop into the plerocercoid. It can happen that this fish is ingested by another predatory fish (e.g. pike) which then serves as a paratenic host. The final host (human, dog, cat) is then infected by the intake of the intermediate host (carp fish) or the paratenic host pike.