Diphyllobothrium pacificum, a Tapeworm from Sea Lions Endemic in Man Along the Coastal Area of Peru

Abstract

Insisting on the difficulty of identifying species of the genus Diphyllobothrium, the author draws attention to the peculiar life cycle of Diphyllobothrium norvegicum, which needs four hosts. Diphyllobothrium pacificum (Nybelin, 1931) Margolis, 1956, evolves entirely in a marine habitat; it is a tapeworm of sea lions and is much more frequent in man in Peru than was supposed (60 cases). Because of the ecological food chain in the Peru Current and the fact that the anchoveta is only used for fish meal, the author concludes that man is infested through a paratenic host. Although more than 700 current food fish have been examined for plerocercoid larvae, it has not been possible to identify with certainty a particular plerocercoid since both human and canine experimental infestations were unsuccessful. The mode of human infestation is without doubt through the Peruvian national dish known as cebiche, consisting of raw fish steeped in lime juice with peppers, which is sold not only in restaurants but also on the streets. It is also more than likely that D. pacificum was already a parasite of pre-Columbian man.