Two cases of human Echinostoma hortense infection and their probable infection source were identified by praziqantel (Distocide) treatment of the patients and by examining two kinds of fresh water fish which were eaten raw by them. The result of the research can be summarized as follows: The patients, each aged 31 and 30, were residing in the same house in Wonju City, Kangwon Province. The first case was hospitalized due to epidemic hemorrhagic fever (E.H. fever) and the second case was healthy but had slight degree of abdominal pain and diarrhea from time to time. In the stool examination, eggs of E. hortense (114.3 x 71.0 micrometer average from the first case and 119.1 x 68.3 micrometer average from the second) were found. By administering single dose of praziquantel (10~15 mg/kg) and purgation with magnesium salt to them, six adults of E. hortense were collected from the diarrheal stools of the second case. By examining 84 Moroco oxycephalus and 20 Carassius carassius which were captured at the place where the two patients had captured and eaten the fresh water fish, the metacercariae of Echinostoma sp. were found from 3 (3.5 percent) M. oxycephalus. After the experimental infection of 3 isolated metacercariae to one albino rat three adults of E. hortense were recovered. By the present study, the two patients revealing the echinostomatid eggs in their stools were proven to be infected with E. hortense and to be the second and third human cases of this fluke infection in Korea. Moroco oxycephalus harboured the metacercariae of E. hortense and appeared to be a new second intermediate host.
parasitology-helminth-trematoda ; Echinostoma hortense ; case report ; intermediate host ; rat ; Moroco oxycephalus ; Carassius carassius

Recently there have been some reports on human infections of Echinostoma hortense in Korea. It was found that a few species of freshwater fishes were playing the role of the second intermediate host of E. hortense. However, molluscan intermediate host has not been identified yet in Korea. The present study aimed to establish the life cycle of E. hortense in laboratory. Experimental studies such as egg production from the rat, development of the eggs in vitro, exposure of miracidia to freshwater snails, shedding pattern of cercariae from infected snails, morphology of cercariae, cercarial infection to the second intermediate host and infection of metacercariae to the difinitive hosts were done. In addition, epidemiological surveys on the infection status in inhabitants and house rats, and on the natural infection of larval echinostomes in the snails and fishes were carried out along the South Hangang-river. The results obtained were as follows: The eggs deposited from adults in physiological saline were cultivated at room temperature (20-24C). The miracidia were firstly observed on 8 days after cultivation, and 85.5 per cent of the eggs contained the mature miracidia on 11 days after cultivation. More than 90 per cent formed the miracidia when cultivated at temperature 22-27C. Hatching of the miracidia began on 12 days after cultivation and continued for a week. The size of the miracidia was 103.0 x 51.4 micrometer in average. The motility of miracidia were active up to 8 hours after shedding, but they were all dead within 10 hours after shedding. A freshwater snail, Radix auricularia coreana was cultivated in aquaria. A hatched F1 snails from the egg masses were exposed to 20 miracidia respectively. Escape of cercariae started on 15 days after infection. Radix auricularia coreana was experimentally identified as the first intermediate host of E. hortense in Korea. Cercarial shedding started on 15-20 days after infection by snail, continued for about 10 days (8.8 days in average). Infected snails were dead within 32 days after the miracidial infection. About 1,335 cercariae (328-1,994) per snail were shed in its life, and 119 cercariae in average per snail per day were shed. The cercariae were motile for more than 24 hours, and then squirming at the bottom until death. The body and tail sizes of cercariae were 356 x 186 micrometer and 510 x 68 micrometer in average, respectively. The rediae parasitized in the snail hosts were found mainly around the pericardial regions, and their size was 1,575 x 258 micrometer in average. The numbers of developing cercariae in a mature redia were 14 in average (7-20 in range). The numbers of rediae in a snail were 102 in average on 15 days after miracidial infection and 221 in average on 28 days. Three uninfected Misgurnus anguillicaudatus, less than 6.5 cm long were used in for the cercaria1 infection. They were all exposed with 755 cercariae, and examined at 5-day intervals starting from 10 days after infection. All the fihes were infected with metacercariae of E. hortense and a total of 275 was found infected (36.4 per cent). The metacercariae were fed to rats and the adult worms were obtained on 15 days after infection. The infected rats began to deposit the eggs on 11 days after infection. The number of eggs deposited per day per worm (EPD/worm) was 400-500 on 3 weeks after infection and was increased to 1,000-1,500 on 4 to 17 weeks, then decreased to 800 on 2l weeks after infection. A total of 745 stool specimens collected from 576 male and 169 female residents of 8 different villages along South Hangang basin was examined. Out of 745 specimens, the eggs of Echinostoma sp. were found in 2 cases (0.3 per cent). Of 34 house rats one showed egg-positive (2.9 per cent). Total 971 Radix auricularia coreana collected from 7 sampling stations were examined for shedding of cercariae. Three snails (0.3 per cent) shed the cercariae of E. hortense. A total of 119 out of 542 freshwater fishes (22.0 per cent) had the metacercariae of E. hortense. The fishes parasitized with the metacercariae were 4 out of 14 examined species. The infection rate of 4 species were 34.1 per cent (106 out of 311) in Misgurnus anguillicaudatus, 30.4 per cent 7 out of 23) in Misgurnus mizolepis, 4.3 per cent (2 out of 46) in Moroco oxycephalus and 22.2 per cent (4 out of 18) in Odontobutis obscura interrupta. In summarizing the above results, the first intermediate host of E. hortense was found as Radix auricularia coreana in Korea. Also it took about 46 days for the shortest completion of a life cycle of E. hortense in summer; that is, 10 days for miracidial development in eggs, 15 days for cercarial development in the snail, about 10 days for metacercarial development in the second intermediate hosts, 11 days for the maturation as the adults in the definitive hosts. The natural infection rates of E. hortense in the intermediate hosts were relatively high but those in the definitive hosts were low in the middle areas of South Hangang basin.
parasitology-helminth-trematoda ; Echinostoma hortense ; epidemiology ; biology ; Misgurnus anguillicaudatus ; Misgurnus mizolepis ; Moroco oxycephalus ; Odontobutis obscura interrupta ; Radix auricularia

: A study of infestation patterns for larval trematodes from fresh-water fish and brackish-water fish was carried out during the period from June to October in 1982. They were collected by netting, fishing with rod and line, and using the bait of crushed oil cake in a transparent plastic bowls at the three localities, Daebon-dong, Kugil-dong, and Hoam-dong in the river Taechong, Kyungpook Province, Korea. Five species of fresh-water fish, the crussian carp, Carassius carassius Linnaeus, the bullhead, Coreobagrus brevicorpus Mori, the fat minnow, Moroco oxycephalus (Bleeker), the flat bitterling, Paracheilognathus rhombea(Temminck et Schlegel), and the catfish, Parasilurus asotus (Linnaeus), and two kinds of brackish-water fish, the grey mullet, Mugil cephalus (Linnaeus) and the sweetfish, Plecoglossus altivelis (Temminck et Schlegel) were examined. Four species of the metacercariae, Exorchis oviformis, Metacercari hasegawai, Metorchis orientalis and undetermined larvae were found. Of these, the encysted larvae of the human intestinal fluke, Metagonimus yokogawai, were found from three kinds of fresh-water fish, the crussian carp, the bullhead and the fat minnow and one species of brackish-water fish, the sweetfish and the infestation rates for the larvae varied appreciably from fish to fish. The intensity of infestation with the Metagonimus larvae in the three species of fresh-water fish as low, and the average number of the larvae per gram of flesh varied from 0.5 to 0.2. By comparison, the brackish-water fish was more heavily infested and the mean number of cysts per gram of flesh in Plecoglossus altivelis was 109.2. It was found that infection with Metagonimus yokogawai is caused by consuming raw fresh-water fish and brackish-water fish caught in the river Taechong, Kyungpook Province, Korea.
parasitology-helminth-trematoda ; Metagonimus yokogawai ; Carassius carassius ; Coreobagrus brevicorpus ; Moroco oxycephalus ; Paracheilognathus rhombea ; Parasilurus asotus ; Mugil cephalus ; Plecoglossus altivelis ; epidemiology ; metacercaria

The present study was undertaken to determine the pattern of infestation with the encysted larvae of digenetic trematodes in freshwater fish collected in both the natural and fish breeding ponds in Kyungpook Province, Korea. The fish collected in the two natural ponds, Nass-chil, and Sa-il, and three fish breeding ponds, Deok-dong, Mo-gok, and Seongryu-tunnel, were examined from July 1980 to August 1981. The data were compared with the results obtained from freshwater fish caught in the river Kumho by Hwang and Choi(1980). Ten species of fish caught in the ponds were examined for the presence of the larval trematodes. Seven species of the larvae, Clonorchis sinensis, Cyathocotyle orientalis, Echinochasmus species, Exorchis oviformis, Metacercaria hasegawai, Metagonimus yokogawai, and Metorchis orientails and two kinds of undetermined cyst A and B were found. The infestitation rate for Clonorchis sinensis metacercaria in the Korean shiner, Gnathopogon atromaculatus collected in the natural ponds was higher than the rate in the river Kumho by Hwang and Choi(1980), but lower in the fish collected in the breeding ponds. By contrast, the infestation rate in the flat bitterling, Paracheilognathus rhombea in ponds was higher, while there was no change of the rate in the southern top-mouthed minnow, Pseudorasbora parva. The intensity of infestation, expressed as the average number of Clonorchis sinensis metacercaria per gram of flesh, were lower than in the bullhead, Coreobagrus brevicorpus, and Gnathopogon atromaculatus in the ponds in 1981. The intensity was higher in Paracheilognathus rhombea, but no fluctuation in the intensity of infestation in Pseudorasbora parva was observed. The infestation rates and densities for the encysted larvae of digenetic trematodes except for Clonorchis sinensis varied from fish to fish. However, it was found that the rate and intensity of the larval trematodes from all the fish in the ponds was lower than from those in the rivers in Kyungpook Province, Korea.
parasitology-helminth-trematoda ; Clonorchis sinensis ; Cyathocotyle orientalis ; Echinochasmus species ; Exorchis oviformis ; Metacercaria hasegawai ; Metagonimus yokogawai ; Metorchis orientails ; Pseudorasbora parva ; Coreobagrus brevicorpus ; Gnathopogon atromaculatus ; Paracheilognathus rhombea ; Carassius carassius ; Coreoperca herzi ; Cyprinus carpio ; Lipomis macrochirus ; Moroco oxycephalus ; Zacco platypus ; epidemiology

In an attempt to clarify the epidemiological feature of C. sinensis in Mangyeong riverside area, the prevalence of clonorchiasis, infestation rate of the cercariae in Parafossarulus manchouricus, and detection rate of the metacercariae in fresh-water fishes were investigated from March 1 to September 30, 1983 at the upper, middle and lower reaches of the river. The results obtained were summarized as follows:Detection rate of C. sinensis egg among inhabitants was 8.2 percent out of a total of 1,266 persons. but the differences in detection rates were not statistically signifcant among upper, middle and 1ower reaches. According to sex, the detection rates were 10.3 percent in male and 6.1 percent in female (p<0.05), but by age groups, increases of the rates were observed as increase in age (p<0.05). Out of a total of 380 fresh-water fishes of 32 different species, 93 fishes (25 percent) of 12 species were found positive with Clonorchis metacercariae, and there were differences in infection rates of the metacercariae among the fishes in 3 parts of the river; 11 percent in upper, 35 percent in middle, and 34 percent in lower reaches respectively. The metacercarial detection rates from various fishes were 97 percent in Pseudorasbora parva, Cultriculus eigenmanni (85 percent), Gnathopogon strigatus (67 percent), Microphysogobio yaluensis (50 percent), Gnathopogon coreanus (47 percent), Pungtungia herzi(44 percent), Abbottina rivularis (40 percent), Moroco oxycephalus (33 percent), Coreoleuciscus splendidus (32 percent), Gnathopogon majimae (26 percent), Rhodeus ocellatus (7 percent), and Aphyocypris chinensis (3 percent) respectively. Although very few P. manchouricus were collected at upper reach, 12 snails (0.7 percent) among a total of 1,713 were found infected with Clonorchis cercariae. Also the cercariae of Echinochasmus japonicus (7.99 percent), Lexogenes liberum (0.99 percent), Cyathocotyle orientalis (0.75 percent), Exorchis oviformis (0.23 percent) and Asymphylodora japonica (0.05 percent) were detected from the snails.
parasitology-helminth-trematoda ; Clonorchis sinensis ; clonorchiasis ; epidemiology ; Pseudorasbora parva ; Cultriculus eigenmanni ; Gnathopogon strigatus ; Microphysogobio yaluensis ; Gnathopogon coreanus ; Pungtungia herzi ; Abbottina rivularis ; Moroco oxycephalus ; Coreoleuciscus splendidus ; Gnathopogon majimae ; Rhodeus ocellatus ; Aphyocypris chinensis ; Parafossarulus manchouricus ; Echinochasmus japonicus ; Lexogenes liberum ; Cyathocotyle orientalis ; Exorchis oviformis ; Asymphylodora japonica