Infestation of larval trematodes from fresh-water fish and brackish-water fish in River Hyungsan, Kyungpook Province, Korea

ABSTRACT

In order to determine the infestation patterns for metacercaria of digenetic trematodes, several kinds of fresh-water and brackish-water fish were caught in River Hyungsan, Kyungpook Province, Korea and examined from March to October in 1983. They were collected by netting, fishig with rod and line, or using the bait of crushed oil cake in transparent plastic bowls, and were dissected into the flesh, scales and fins with tail, and then examined for the presence and infestation density of larval trematodes. Of the 11 kinds of fish examined, the encysted larvae of Exorchis oviformis were found all of them, Metagonimus yokogawai from 9 kinds, Cyathocotyle orientalis, Metacercaria hasegawai and Metorchis orientalis from 6 kinds, and Clonorchis sinensis from 4 kinds in the present study. In the intensity of infestation with Clonorchis sinensis, the Korean shiner, Gnathopogon atromaculatus Nichols et Pope, was the most heavily infected species, the average number of metacercariae per gram of fish flesh being 45.5, followed by the striped shiner, Puntungia herzi Herzenstein 11.6, and Southern top-mouthed minnow, Pseudorasbora parva (Temminck et Shlegel), 9.7. The intensity of infestation with the Metagonimus larvae in 8 species of fresh-water fish was relatively low, and the average number per gram of flesh varied from 0.23 to 9.1. In comparison, the brackish-water fish were more heavily infected and the mean number of cysts per gram of flesh in the sweetfish, Plecoglossus altivelis, was 32.9. The results of this study generally indicate that Clonorchis sinensis and Metagonimus yokogawai infection may occur by consuming raw fresh-water fish caught in the river Hyungsan, Kyungpook Province, Korea.