An epidemiological study was performed to know the infection status of E. hortense among the human residents and fish intermediate hosts in Chongsong-gun, Kyongsangbuk-do. Out of 263 people examined, 59(22.4 per cent) were positive for the eggs of E. hortense. Total 152 fresh water tishes (9 species) were examined, and Odontobutis obscura interrupta, Misgurnus angullicaudatus and Squalidus coreanus were found to harbour the metacercariae of E. hortense. Juvenile or adult E. hortense were expelled from 35 out of 54 cases treated with praziquantel. The number of worms per individual ranged from l to 649, with the average burden of 51. The eosinophil count of infected persons ranged 1-24 per cent (6 per cent in average). The number of eggs per day per worm (EPDPW) in human host was estimated about 1,478. The results showed that Chongsong-gun is an endemic area of E. hortense.
