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.

Two cases of human Echinostoma hortense infection were found in Seoul Paik Hospital. Their stools revealed echinostomatid eggs. After treatment with praziquantel (single does of 10-12 mg/kg) and purgation with magnesium salt, total 21 flukes were collected in one case. The flukes were 5.9-7.5 mm long, had 27-28 collar spines around their head, laterally deviated ovary and two tandem testes. They were identified as E. hortense Asada, 1926. The cases are 38-year and 20-year old men residing in Seoul, whose hometown is Chungsong-gun and Seungju-gun, Kyongsangbuk-do respectively. They had eaten raw flesh of various kinds of fresh water fishes (both cases) and/or salamander (latter case), which are considered possible sources of this fluke infection. They experienced abdominal discomfort and/or diarrhea. Hematology revealed 22 percent eosinophilia in the latter case, but it became 5 percent after the treatment. Echinostomatid eggs were not found after the treatment in both cases. These are the 4th and 5th human cases of E. hortense infection in Korea.

A human case of Echinostoma cinetorchis infection was found in Seoul Paik Hospital on August 1987. Large trematode eggs, 98.9 x 62.7 micro-m in average size, were detected in stool examination. The eggs had a small-sized operculum and abopercular wrinkling. After treatment with praziquantel(single dose of 16.2 mg/kg) and purgation with magnesium citrate, an adult fluke was collected. It was 8.0 mm long, equipped with 37 collar spines around head crown, and had only one testis just behind the Mehlis' gland. It was identified as E. cinetorchis Ando et Ozaki, 1923. The patient is an 18-year old man residing in Seoul, and was hospitalized due to nephritis. He had eaten raw meat juice of fresh water fishes such as top minnows(Oryzias latipes) and loaches, or tadpoles, which are considered possible souce of this fluke infection. This is the 4th human case of E. cinetorchis infection in Korea.

The results of fecal examination for helminth eggs and protozoan cysts in Seoul Paik Hospital during 1984-1992 are reported. Fecal specimens of a total of 52,552 out- or inpatients were examined by formalin-ether sedimentation and/or direct smear method. The overall egg positive rate of helminths was 6.5% and the cyst positive rate of protozoa 2.5%. The egg positive rate (number of positive cases) for each species of helminth was; Clonorchis sinensis 3.2% (1,667), Trichuris trichiura 2.0% (1,089), Metagonimus yokogawai 1.2% (613), Ascaris lumbricoides 0.2% (100), Trichostrongylus orientalis 0.1% (34), Taenia spp. 0.05% (28), Hymenolepis nana 0.03% (18), hookworms 0.03% (17), Paragonimus westermani 0.02% (12), Echinostoma spp. 0.03% (12), Enterobius vermicularis 0.02% (10), Strongyloides stercoralis (larvae) 0.01% (6), and Diphyllobothrium latum 0.004% (2). The cyst positive rate (number of positive cases) for each protozoan was; Entamoeba coli 1.1% (588), Endolimax nana 0.8% (402), Giardia lamblia 0.3% (173), Entamoeba histolytica 0.3% (164), and Trichomonas hominis (trophozoites) 0.004% (2). Viewing from the data of 9 years, it was evident that the prevalence of soil-transmitted helminths such as A. lumbricoides and T. trichiura has been decreasing remarkably, while that of snail-transmitted helminths such as C. sinensis and intestinal protozoans has not.