Investigation of the infection with Diphyllobothrium nihonkaiense plerocercoids and metagonimus metacercariae in freshwater salmonids cultured in Japan

Abstract

We investigated the existence of Diphyllobothrium nihonkaiense plerocercoids and trematode metacercariae of the genus Metagonimus in salmonid fishes (N = 2,187) cultured in freshwater areas of Japan. The infection of D. nihonkaiense plerocercoid larvae was not detected in cultured freshwater salmonids, whilst five out of 60 wild anadromous masu salmon Oncorhynchus masou masou captured during the spawning migration in the Miomote River was infected with D. nihonkaiense. No Metagonimus metacercariae were detected in any salmonids examined. The present study corroborates the previous report indicating that salmonids cultured in freshwater areas of Japan have no chance of infection with D. nihonkaiense.