Recent patterns of infection with digenetic larval trematodes in fresh-water and brackish-water fish were studied in three locations of the river Taewha during the period from April to October 1988, and compared with the data reported previously in the same river. Of 16 species of fish examined, the encysted larvae of Cyathocotyle orientalis were found most frequently from 9 species of fresh-water fish. The metacercariae of Echinochasmus sp., Metacercaria hasegawai and Metagonimus yokogawai were found 8 species, those of Clonorchis sinensis from 7 species, and Exorchis oviformis and Metorchis orientalis from 5 species of fish. The infection rates of fish with C. sinensis metacercariae were not lower than those reported in 1980, wheres their intensity of infection was found lowered in 3 species, Coreobagrus brevicorpus, Gnathopogon atromaculatus, and Puntungia herzi. The infection rates of 3 species of fish with M. yokogawai metacercariae were lower than the results in 1982, while the rate was higher in 2 species, Zacco platypus, and Z. temmincki, and rather stationary in Plecoglossus altivelis. The intensity of infection in several species of fish appeared rather higher than in 1980. the encysted larvae of C. orientalis, Echinochasmus sp., E. oviformis and Metacercaria hasegawai showed variations in infection rates of fish in 1980 and in the present study. It was found that the rate of infection with digenetic larval trematodes in fresh-water fish was still relatively high in the river Taewha, and the metacercarial burden in the fish varied greatly by different fish in 1980 and in the present study.
parasitology-helminth-trematoda ; Cyathocotyle orientalis ; Echinochasmus sp. ; Metacercaria hasegawai ; Metagonimus yokogawai ; Clonorchis sinensis ; Exorchis oviformis ; Metorchis orientalis ; Coreobagrus brevicorpus ; Gnathopogon atromaculatus ; Puntungia herzi ; Zacco platypus ; Z. temmincki

: A study of infestation patterns for larval trematodes from fresh-water fish and brackish-water fish was carried out during the period from June to October in 1982. They were collected by netting, fishing with rod and line, and using the bait of crushed oil cake in a transparent plastic bowls at the three localities, Daebon-dong, Kugil-dong, and Hoam-dong in the river Taechong, Kyungpook Province, Korea. Five species of fresh-water fish, the crussian carp, Carassius carassius Linnaeus, the bullhead, Coreobagrus brevicorpus Mori, the fat minnow, Moroco oxycephalus (Bleeker), the flat bitterling, Paracheilognathus rhombea(Temminck et Schlegel), and the catfish, Parasilurus asotus (Linnaeus), and two kinds of brackish-water fish, the grey mullet, Mugil cephalus (Linnaeus) and the sweetfish, Plecoglossus altivelis (Temminck et Schlegel) were examined. Four species of the metacercariae, Exorchis oviformis, Metacercari hasegawai, Metorchis orientalis and undetermined larvae were found. Of these, the encysted larvae of the human intestinal fluke, Metagonimus yokogawai, were found from three kinds of fresh-water fish, the crussian carp, the bullhead and the fat minnow and one species of brackish-water fish, the sweetfish and the infestation rates for the larvae varied appreciably from fish to fish. The intensity of infestation with the Metagonimus larvae in the three species of fresh-water fish as low, and the average number of the larvae per gram of flesh varied from 0.5 to 0.2. By comparison, the brackish-water fish was more heavily infested and the mean number of cysts per gram of flesh in Plecoglossus altivelis was 109.2. It was found that infection with Metagonimus yokogawai is caused by consuming raw fresh-water fish and brackish-water fish caught in the river Taechong, Kyungpook Province, Korea.
parasitology-helminth-trematoda ; Metagonimus yokogawai ; Carassius carassius ; Coreobagrus brevicorpus ; Moroco oxycephalus ; Paracheilognathus rhombea ; Parasilurus asotus ; Mugil cephalus ; Plecoglossus altivelis ; epidemiology ; metacercaria

The present study was undertaken to determine the pattern of infestation with the encysted larvae of digenetic trematodes in freshwater fish collected in both the natural and fish breeding ponds in Kyungpook Province, Korea. The fish collected in the two natural ponds, Nass-chil, and Sa-il, and three fish breeding ponds, Deok-dong, Mo-gok, and Seongryu-tunnel, were examined from July 1980 to August 1981. The data were compared with the results obtained from freshwater fish caught in the river Kumho by Hwang and Choi(1980). Ten species of fish caught in the ponds were examined for the presence of the larval trematodes. Seven species of the larvae, Clonorchis sinensis, Cyathocotyle orientalis, Echinochasmus species, Exorchis oviformis, Metacercaria hasegawai, Metagonimus yokogawai, and Metorchis orientails and two kinds of undetermined cyst A and B were found. The infestitation rate for Clonorchis sinensis metacercaria in the Korean shiner, Gnathopogon atromaculatus collected in the natural ponds was higher than the rate in the river Kumho by Hwang and Choi(1980), but lower in the fish collected in the breeding ponds. By contrast, the infestation rate in the flat bitterling, Paracheilognathus rhombea in ponds was higher, while there was no change of the rate in the southern top-mouthed minnow, Pseudorasbora parva. The intensity of infestation, expressed as the average number of Clonorchis sinensis metacercaria per gram of flesh, were lower than in the bullhead, Coreobagrus brevicorpus, and Gnathopogon atromaculatus in the ponds in 1981. The intensity was higher in Paracheilognathus rhombea, but no fluctuation in the intensity of infestation in Pseudorasbora parva was observed. The infestation rates and densities for the encysted larvae of digenetic trematodes except for Clonorchis sinensis varied from fish to fish. However, it was found that the rate and intensity of the larval trematodes from all the fish in the ponds was lower than from those in the rivers in Kyungpook Province, Korea.
parasitology-helminth-trematoda ; Clonorchis sinensis ; Cyathocotyle orientalis ; Echinochasmus species ; Exorchis oviformis ; Metacercaria hasegawai ; Metagonimus yokogawai ; Metorchis orientails ; Pseudorasbora parva ; Coreobagrus brevicorpus ; Gnathopogon atromaculatus ; Paracheilognathus rhombea ; Carassius carassius ; Coreoperca herzi ; Cyprinus carpio ; Lipomis macrochirus ; Moroco oxycephalus ; Zacco platypus ; epidemiology