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.
parasitology-helminth-tematoda ; Echinostoma hortense ; Hippeutis cantori ; epidemiology

The fresh water snail, Hippeutis(Helicorbis) cantori, caught from the rice paddies in Namyangju-gun, Gyeonggi-do, was found to be a new second intermediate host of E. cinetorchis in Korea. The metacercariae were found from 89(76.7 %) out of 116 snails examined and the average metacercarial burden was 4.7 per infected snails. Some developmental characteristics of E. cinetorchis were observed after experimental infection of the metacercariae to rats and mice.
parasitology-helminth-termatoda ; Echinostoma cinetorchis ; Hippeutis cantori ; metacercaria ; epidemiology ; development

The distribution, external morphology, radula, chromosome numbers of Planorbidae snails were studied. The specimens were collected at four stations in Nonsangun, Kongjugun, and Daedukgun which are located around Geum river. Three genera and three species of Planorbidae, Hippeutis cantori, Segmentina hemisphaerula and Gyraulus convexiusculus, were collected. H. cantori was the most abundant species among the three species. G. convexiusculus was the least abundant one. Each species could be identified on the basis of its external characteristic, since the periphery of each species has a peculiar shape. H. cantori was the largest one among the three species. The radula formula of each species was very similar to other species. The size of radula was proportional to the size of shell. The radula formulae of H. cantori, S. hemisphaerula, and G. convexiusculus were 29:1:29, 23:l:23, and 16:1:16 respectively. The difference of radula formula could be found in the total numbers of laternal and marginal teeth. The haploid chromosome number of H. cantori was eighteen (n=18). S. hemisphaerula and G. convexiusculus were assumed to be same in their chromosome numbers (n=18).
malacology ; Planorbidae ; morphology ; chromosome ; epidemiology ; Hippeutis cantori ; Segmentina hemisphaerula ; Gyraulus convexiusculus

The life cycle of Fibricola seoulensis was studied in the laboratory and in the field, with special interests in the larval developments within the eggs and in the intermediate hosts. The first emergence of miracidia after incubation of eggs in 26C water began on the ninth day. The miracidia, elongate and cylindrical shape, had epidermal plates in the formula of 6, 9, 4 and 3, with two pairs of flame cells and lateral processes. A kind of fresh water snail, Hippeutis (H.) cantori, was found to shed furcocercous cercariae from the 13th day after experimental challenge with miracidia while Physa acuta failed to shed. The same kind of snail collected from the field also shed the same cercariae. The cercariae were equipped with 2 pairs of penetration glands and 5 pairs of flame cells. The tadpoles of Rana nigromaculata were found susceptible to experimental infection with the cercariae. The same kind of tadpoles collected from various areas were also found naturally infected. The metacercariae in the tadpoles which were infected experimentally became infective to the definitive host in 21 days. The metacercariae were located free in the body cavity of tadpoles, and attained sexual maturity in rats in 7 days. The present study successfully followed the complete life cycle of F. seoulenis and found that it is possible to maintain the life cycle in the laboratory.
parasitology-helminth-termatoda ; Fibricola seoulensis ; biology ; rat ; Hippeutis cantori ; Rana nigromaculata ; Physa acuta ; intermediate host