The infestation states and changing patterns of human infecting metacercariae in freshwater fish in Kyongsang-do and Kyonggi-do, Korea.

The infestation rates and abundances of human infecting metacercariae (Clonorchis sinensis, Metagonismus spp., Centrocestus armatus, Echinostoma hortense, Echinochasmus japonicus, Clinostomum complanatum) in freshwater fish were investigated at the three river areas-Taewhagang (river), Hyongsangang (river), Nakdonggang (river) -in Kyongsang-do and at four streams-Yonpungchon, Munsanchon, Kyonganchon, and Konjiamchon-in Kyonggi-do, Korea in 1994-1995. The fish caught at Taewhagang were heavily infested with metacercariae of Clonorchis sinensis and Centrocestus armatus. At Hyongsangang, Zacco platypus and Z. temmincki were moderately infested with metacercariae of C. armatus. Chomanpo, at the basin of Nakdonggang, was still endemic for C. sinensis. In the fish caught at four streams of Kyonggi-do, metacercariae of C. sinensis exhibited the highest infestation rate and intensity out of 6 species of metacercariae. The infestation intensity of C. sinensis metacercariae in fish flesh was markedly different according to each division of flesh. The cause of this difference was conjectured as a result of larval behavior. The metacercariae of C. armatus were found in almost all parts, except scales and fins, of fish. The infestation rates and intensities of C. sinensis and C. armatus metacercariae in Taewhagang greatly increased as compared with those of previous reports. Rhinogobius brunneus and Acanthorhodeus macropterus are newly recorded intermediate hosts of Echinostoma hortense. The reason of large differences from previous data was discussed and the standard method of metacercaria examination was proposed.