• Journal of Food Hygiene and Safety
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• v.12 no.4
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• pp.300-303
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• 1997

The present study was carried out to know the distribution of freshwater mollusk on the chinese liver fluke in the middle of August, 1997 at the upper area of Kyungan stream located in Yongin Kun, Kyungki province. The snails were collected from the shallow and irrigation route in a rural area located along the upper area of Kyungan stream. The snails collected by hand were brought to the laboratory and cercariae naturally shed from the snails, Parafossarulus manchouricus were examined. Parafossarulus manchouricus is medically important intermediated host of the transmission of digenetic trematoda to human. Each snail was placed in aerated tap water for the detection of ceracariae and examined for expelled cercariae. Infection rate of the cercariae of Clonorchis sinensis was 3 (1.5%) among 195 individuals collected in the habitat. The identification of the cercaria of Clonorchis sinensis was performed as described by Komiya and Tajimi.

• The Korean Journal of Malacology
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• v.3 no.1
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• pp.35-43
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• 1987

Morphological variations of six Korean and one Japanese populations of Parafossarulus manchouricus were observed. Mean length of shell was 9.36mm(n=376), and mean width was 8.0mm. Average aperture length and width were 4.72 and 3.78mm, respectively. Number of whorl ranged from 3.5 to 5.25(at most 4.5)in all popuiations . Yangsoori population had no spiral line or spiral keel, but ther populations had spiral lines. Number of spiral line on their penultimate shorls ranged 4 to 14.The lips of aperture were generally thickened, except in some Chongpyong, Haman and Fukuoka populations. The most of shell was eroded in only apex part and/ or in othker sculpture, especially Yangsoori population was heavily eroded.

• Parasites, Hosts and Diseases
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• v.21 no.2
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• pp.193-204
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• 1983

The Jinyang Lake is dammed up Nam River, and surrounded by Jinju city and four counties; Jinyang, Sanchong, Hading, and Sachon in kyongsang-Nam-Bo, Korea. The areas around this man-made lake have been known as an endemic focus of clonorchiasis in Korea. The present study was first aimed to know the distribution of freshwater mollusks including medically important snails, and larval trematodes shed from Parafossarulus manchouricus and Semisulcospira libertina. In addition to above studies, water analyses in each snail habitat were carried out in order to figure out a part of their environmental factors. This malaco-ecological survey was done at the sirs areas around upper, middle and lower parts of the lake for 4 months, August-November, 1983. Total nine species of freshwater mollusks were collected throughout the study: 4 species of gastropods: Semisulcospira libertina, Cipangopaludina chinensis, Parafossarulus manchouricus and Radin auricularia, and 5 species of bit.alves; Unio dcuglasiae, Ancdonta woodiana, Lamprotula gottschei, Corbicula yuminea and Limncperma lucustris. Out of nine species of freshwater mollusks, three species of gastropods; S. Zibertina, p. manchouricus and R. auricularia were medically important in terms of the transmission of digenetic trematodes to humans. P. manchouricus and R. auricularia were mainly collected from the shallow ponds and the irrigation channels with the muddy basin, but S. libertine and the bivalves were only collected from the stream of Nam River where the gravels and rocks were dominant. The levels of dissolved oxygen (D.O.) and biochemical oxygen demand \(B.O.D._5)\ of the water specimens sampled from the study areas ranged from 6.0 to 9.6 ppm and from 0.4 to 1.6 ppm respectively. As a result, it is considered that water system around the Jinyang Lake might be relatively clean without any heavy pollution of aquatic microorganisms and organic materials during the period of this study. On the other hand, eight metalic constituents from the water samples were also assayed, and all metalic ions detected were remarkably low below the legal criteria. However, calcium ion in the water samples from the habitats of P. manchouricus was considerably higher than others. Infection rates of digenetic trematodes in the snails were 6.9% in P. manchouricus and 4.8% in S. libertine, respectively. P. manchouricus snails harboring with thc cercariae of Clonorchis sinensis were only 0.14% among the snails examined, and other trematode cercariae except cercaria of C. sinensis were: furcocercus cercariae, cercaria of Loxogenes liberum type I and II. S. libertine snails parasitized with the cercariae of Metagonimus yokogawai were 1, 5% out of the snails examined, and no cercaria of Paragonimus westermani was found in S. libertine snails in the present study. Digenetic trematode cercariae other than M. yokogawai observed in S. libertina snails were: Cercaria yoshidae (B type) , Cercaria cristata, Cercaria innominatum, Cercaria of Centrocestus formosanus and Cercaria nipponensis.

• The Korean Journal of Malacology
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• v.1 no.1
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• pp.24-50
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• 1985

Five different populations of Parafossarulus manchouricus (Chongpyung, Chinju and Kunsan, Korea; and Japan and Taiwan), a population of Bitbynia (Gabbia) misella (Gongju, Korea) and two different populations of Bithynta tentaculata (Michigan, U.S.A. and Bodensee, Germany) were compared in regard to eff-laying characteristics, morphology, chromosome cytology, natural infections of parasites and ecology of habitats. A satisfactory culture method was devised for laboratory rearing of the snails. Tropical fish food (Terra SML) and powdered green leaves (Ceralife) were used as the main food sources for the snails. Benthic diatoms such as Navicula and Gomphonema from the periphyton were also essential for satisfactory growth, especially for the baby snails. The aquaria were stabilized with small stones from a local stream. Young P. manchouricus snails grew to adult size in about 54 days after hatching. They laid eggs 150-156 days after hatching. The whole cycle (birth to egg-laying) took approximately 5 months. The three species of bithyniid snails are iteroparous and lay eggs once a year. There were no major morphological differences in the shells of genera or subgenera studied here. They did exhibit the following rather minor differences. The shell of Parafossarulus has spirally raised ridges, and its apex is usually eroded; the other two genera lack these characteristics. The shell of B. (Gabbia) misella is small, nor exceeding 7.5 mm in length, while the shells of the other two species are larger, being more than 10 mm in length. Scanning electron microscopy (SEM) of the protoconch of P. manchouricus reveals nearly smooth sculpture with small, low, spiral wrinkles. This sculpture is quite different from that of the Hydrobiidae, a family to which the bithyniids are frequently assigned. Scanning electron microscopy of the radulae of the three bithyniid species showed that their radular morphologies are very similar, but there are some small differences, which may be species-specific. There were some statistical differences in shell heights between the Korean and the other populations of P. manchouricus, and between this species and the other two bithyniids as well. The shell differences between the several populations of Korean P. manchouricus may be related to environment. Edtails of the chromosome cycle of these bithyniid snails are similar to those reported for other snails. No specific differences were observed in the chromosome cycle between the various species and populations of snails employed in this study. Reporred for the first time in molluscs are two darkly stained "nucleolar organizers" during pachyterne stages of meiosis. Two different chromosome numbers were observed in the three bithyniid species: n=17 in B. tentaculata and P. manchouricus, and n=18 in B. (G.) misella. no sex chromosomes or supernumerary chromosomes were seen. There were no morphological differences in karyotypes of three Korean strains of P. manchouricus. The infection rates of cercariae of Clonorchis sinensis in Chinju and Kunsan strains of P. manchouricus were 0.14% and 1.25%, respectively. However, Clonorchis cercariae were found in Chongpyung strain of P. manchouriceu and Gongju strain of B. (G.) misella. The habitats of P. manchouricus around Jinyang Lake were relatively clean without any heavy pollution of aquatic microorganisms and organic materials during the period of this study. The levels of dissolved oxygen (D.O.) and biochemical oxygen demand (B.O.D.) of the water specimens sampled from the study areas ranged from 6.0 to 9.6 ppm and from 0.4 to 1.6 ppm, respectively. Eight metalic constituents from the water samples were also assayed, and all metalic ions detercted were remarkably low below the legal criteria. However, calcium ion in the water samples from the habitats of P. manchouricus was considerably higher than others.

• The Korean Journal of Ecology
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• v.11 no.1
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• pp.37-53
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• 1988

The most medically important snail species of Korea is Parafossarulus manchouricus, a member of the freshwater prosobranch family Bithyniidae. The human parasite that this snail transmits is Clonorchis sinensis, the "Chinese live fluke". On the other hand, this snail has physiological characteristics that reduce the turbidity of freshwater by its filiter feeding activity. However, a few basic studies have been carried out so far. The present studies were attempted to know 1) the possibility of culturing the snails and 2) allozyme variations among 5 local populations of this bithyniid snails. As the results of the studies, P. manchouricus was able to be cultivated in the lavoratory and showed considerable allozyme variations especially in the Chongpyung and Paldaing populations out of those collected from 5 localities in Korea. It is quite suggestive that the endemicity of clonorchiasis might be related to the allozyme variability.

• Parasites, Hosts and Diseases
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• v.21 no.1
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• pp.11-18
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• 1983

As a part of observation on the suitability as a second intermediate host of Clonorchis sinensis, various infection experiments were tried to Cyprinus carpio nodus. The results obtained were summarized as follows: 1. The cercariae which attempted to contact with Cyprinus carpio nodus in the water were observed under the stereomicroscope. After contact, cercariae began to separate its tails from the bodies at 4 minutes increasingly, and then the numbers ranged to 80% at 13 minutes after the encounter. But very few cercariae could actually invade into the epidermis of the fish. 2. When Cyprinus carpio nudes were exposed to a number of cercariae in the beaker, only a few cercariae could invade through the epidermis. Most of the invaded cercariae were killed before forming the cyst. Also rare encysted cercariae were found to be dead within 48 hours. 3. Cyprinus carpio nudes were reared with Parafossarulus manchouricus shedding numerous cercariae in the indoor aquarium. When observed after 12 days, to determine the susceptibility, no metacercaria was found infected. 4. Cyprinus carpio nudum were reared with Parafossarulus manchouricus shedding numerous cercariae in Kimhae lake for 2 months in summer of 1982, in order to check the natural infection. No metacercaria of Clonorchis sinensis was found from the fish. 5. In the cases of control fish, Pseudoraibora larva, numerous cercariae were inspected on the course of invasion through epidermis of the fish under the stereomicroscope. And many metacercariae were also found from the Ssh whenever they were kept in beaker, indoor aquarium, or the lake for natural infection. The results suggested that Cyprinus carpio kudus might not be proper intermediate host of Clonorchis sinensis.

• Journal of Environmental Health Sciences
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• v.6 no.1
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• pp.10-21
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• 1979

In preventing the infection of Clonorchis sinensis, there is one way in which life cycle of Clonorchis sinensis is cut off by eradicating the first intermediate host viz Parafossarulus manchuoricus, with molluscicides or insecticides. This survey was carried out in order to evaluating the molluscicidal effect of several insecticides upon P. manchauricus. In this survey, diazinon, heptachlor, E.P.N., E.M., and malathion was applied as molluscidies. Those insecticides had been generaly used in farming area. The results are summarized as follows. 1) In molluscicidal effect, E.M. showed the higher molluscicidal effect than any other insecticides in all experiment parts, and the order of insecticides upon molluscicidal effect was that of E.M., E.P.N., heptachlor and malathion. 2) $LD_{50}$ values are varied according to the exposure time in insecticide solution, and the longer the exposure time is, the lower the values of $LD_{50}$ is. 3) To take the exposure time in low concentration of insecticide solution for the long time would obtain the more molluscicidal effect. 4) The mortality rate increases in proportion as the concentration of insecticides increases.

• The Korean Journal of Malacology
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• v.1 no.1
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• pp.1-4
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• 1985

The investigation of freshwater molluscs in the South Han River was carried out from 1984 and in 1985. The authors selected 12 stations and collected freshwater snails and mussels. We here publish the catalogue of molluscs in South and North Han River. The catalogue of molluscs in the South Han River is as follows; two classes, four orders, six families including twenty species(Semisulcospira coreana, Semisulcospira globus, Semisulcospira gottschei, Semisulcospira forticosta, Parafossarulus manchouricus, Gabbia misella, Radix auricularia coreana, Austroppepleaollura, Limnoperma lucustris, Lamprotula gottschei, Lanceolariaacrorhyncha, Unio douglasiae, Unio sp, Solenaia triangulalis, Anodonta fukudai, Anodonta woodiana, Corbicula felnouilliana, Corbiculafluminea, Corbicula sp).

• The Korean Journal of Malacology
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• v.28 no.1
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• pp.13-19
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• 2012

To determine the status of Korean molluscs infection and relation with climate change of Korean peninsula, references were reviewed. Wild animals serve as intermediate, reservoirs and paratenic hosts to zoonotic parasites of human beings. Trematode are common parasites of molluscs and almost all trematodes infect mollusks as the first host in the life cycle, and most have a complex life cycle involving other hosts. The significance of auxiliary hosts to the ecology of the parasite has not been proper discussion. There is increasing concern as to the impact of climate change on the epidermiology of many parasitic diseases. A total of 21 species for snail transmitted parasites from Korean molluscs has been reviewed. Among them, 15 species was aquatic mollusks and 6 species for marine mollusks. Maximum infections belonged to Semisulcospira livertina had 11 kind of parasite pathogenic organisms, including Paragonimus westermani, Metagonimus yokogawai, Centrocestus armatus, Notocotylus magniovatus, Centrocestus formosanus, incerte cercaria, nipponensis cercaria, Yoshidae cercaria, cristata cercaria, innominatum cercaria and Metagonimus sp. And 11 in Parafossarulus manchouricus including Clonorchis sinensis, Asymphylodora japonica, Cyathocotyle orientalis, Exorchis oviformis, Notocotylus attenuatus, Echinochasmus japonicus, Loxogenes liberum, Cercariae of Loxogenes liberum Type I, Cercariae of Loxogenes liberum Type II, Furcocercus cercariae (Family Sanguincolidae) and Cercaria of Mucobucaris, 10 in Semisulcospira sp. including Paragonimus westermani, Metagonimus yokogawai, Centrocestus armatus, Echinochasmus redioduplicatus, Notocotylus magniovatus, Cercaria incerte, Cercaria nipponensis, Cercaria yoshidae, paludinarum cercaria and Metagonimus sp., 7 in Koreanomelania globus including Pseudexorchis major, Cercaria of parapleurolophocercous type, Metagonimus sp. (A & B), Cercaria nipponensis, Cercaria inserta and Cercaria yoshidae. Also, Tapes philippinarum have 3 pathogenic organisms including Cercariae tapidis, Cercariae furcocercus and Parvatrema sp. In particular, under climatic extremes such as floods and drought, aquatic molluscs may play a more prominent role in parasite transmission in the future.

• Parasites, Hosts and Diseases
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• v.21 no.2
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• pp.157-166
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• 1983

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 : 1. Detection rate of C. sinensis egg among inhabitants was 8.2% out of a total of 1,266 personsr, but the differences in detection rates were not statistically significant among upper, middle and lower reaches. According to sect, the detection rates were 10.3% in male and 6.1% in female (p<0.05), but by age groups, increases of the rates were observed as increase in age (p<0.05). 2. Out of a total of 380 fresh-water fishes of 32 different species, 93 fishes (25%) 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% in upper, 35% in middle, and 34% in lower reaches respectively. The metacercarial detection rates from various fishes were 97% in Pseudorasbora larva, Cultriculus eigenmanni (85%) , Gnathepogon strigatus (67%), Microphysogobio yaluensis (50%), Gnathopogon coreanus (47%), Pungtungia hergi (44%), Abbotting riwularis (40%), Moroco oxycephalus (33%), Coreoleuciscus splendidus (32%), Gnathepogon majimap (26%), Rhodeus ocellatus (7%), and Aphyocypris chinensis (3%) respectively. 3. Although very few p. manchouricus were collected at upper reach, 12 snails (0.7%) among a total of 1,713 were found infected with Clonorchis cercariae. Also the cercariae of Echinochasmup iapenicus (7.99%), Lexogenes liberum (0.99%), Cyathocotyle orientalis (0.75%), Esorchis oviformis (0.23%) and Asymphylodora japonica (0.05%) were detected from the snails.