경북 청도천에서 채집된 담수어에 있어서 흡충류 피낭유충의 최근 기생상

Abstract

Recent pattern of infections with digenetic larval trematodes from fresh- water fish was studied in three locations of the River Cheongdo during the period from March to November; 2007; and compared with the data reported previously in the same river. The fish were collected using following techniques: fishing; throwing a castnet; and using a bait of crushed oil cake in a transparent plastic bowl. Of 18 species of fish examined; 11 species of encysted larvae; Clonorchis sinensis; Cyathocotyle orientalis; Centrocestus armatus; Clinostomum complanatum; Exorchis oviformis; Echinochasmus species; Holostephanus species; Metagonimus species; Metacecaria hasegawai; and Metorchis orientalis; Pseudexorchis major and two kinds of undetermined cyst A and C were found. The encysted larvae of Cyathocotyle orientalis and Metacercaria hasegawai were found most frequently from 13 species of fresh-water fish; followed by Exorchis oviformis larvae from 10 species; the cyst of Metagonimus species from 9 species; Clonorchis sinensis from 8 species; Clinostomum complanatum from 6 species; and Centrocestus armatus; Echinochasmus species; Metorchis orientalis; and Pseudexorchis major from 2 species. The infection rates of fish with Clonorchis sinensis larvae were lower than those reported in 2002; whereas their intensity of infection was found lowered in 3 species; Pungtungia herzi; Saurogobio dabryi; and Squalidus japonicus coreanus. The infection rates and intensity of 6 species of fish with Metagonimus species larvae were lower than the results in 2002; while the rates in several species of fish with Exorchis oviformis rather higher. The encysted larvae of Cyathocotyle orientalis; Metacercaria hasegawai; and Metorchis orientalis showed variations in infection rates of fish in 2002 and in the present study. However; it was impossible to compare the infection rates for the encysted larvae on the scales; fins and tail as they varied so considerably in both 2002 and 2007 surveys. This study indicates that the rate of infection with digenetic larval trematodes in fresh-water fish was still relatively high in the River Cheongdo; and the metacercarial burden in the fish varies greatly by different fish in 2002.