• Archives of Pharmacal Research
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• v.21 no.6
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• pp.744-748
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• 1998

Several praziquantel derivatives have been prepared by the acylation of compound 5, and examined on their biological activity in vitro agninst adult clonorchis sinensis collected from rabbits infected with metacercariae which was isolated from Pseudorasbora parva, a second intermediate host, captured in Nakdong river in Korea.

• Parasites, Hosts and Diseases
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• v.41 no.1
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• pp.41-45
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• 2003

Effects of gamma irradiation on the worm survival and chromosomal aberration of Clonorchis sinensis were studied. The metacercariae irradiated with various amounts of gamma radiation (ranging from 5 Gy to 50 Gy) were fed to rats, and the effects were compared with those of non-irradiated controls. Recovery rates of adult worms in irradiated groups were reduced gradually as increasing of the irradiation doses. No worm was recovered from rats which were fed with 50 Gy irradiated metacercariae. The chromosome number was 2n = 56 in all worms from all experimental groups. However, the groups irradiated with 20 Gy, 25 Gy or 30 Gy showed variations in the chromosome number, depending on different cells in the same individual. Radiation doses used in this study did not appear to induce chromosome aberrations, however, irradiation with 30 Gy showed slightly reduced chromosome size.

• Korean Journal of Veterinary Research
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• v.9 no.1
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• pp.71-78
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• 1969

The present studies were undertaken to determine accurately whether Korean native fresh-water shrimps can serve as the second intermediate host of Clonorchis sinensis. The experimental results obtained were as follows; 1. Metacercaria of Clonorchis sinensis was not discovered in 36 Macrobranchium nipponensis (De Hann), 1992 Palaemon paucidens (De Hann) and Palaemon madestus Heller, and 860 Caridina leucastica Stimpson, collected in Kimhae district, which were digested in artificial gastric juice, using binocular dissecting microscope. 2. Cercariae of the Chinese liver fluke could not approach the body wall of young shrimps due to streaming caused by their motion. 3. Young Palaemon spp. of 247 were divided into two groups and placed in two different room aquariums, one is at high temperature, the other is normal. Then they were contacted with the cercariae. Only 11 degenerated metacercariae were found in 9 Palaemon spp. It was suggested that they had died immediately or within a few days after penetration. Furthermore the temperature did not affect the infective ratio. 4. At the field experimental aquarium, no metacercaria of Clonorchis sinensis was discovered tn 100 Palaemon spp. which had been brought into contact with 5000 Parafossarulus manchouricus two trials. 5. Specific changes in the cercariae mixed with the extract of shrimps meat were not observed through the dissecting microscope. 6. These results suggest that the Korean native shrimps cannot serve as the intermediate host of Clonorchis sinensis.

• Korean Journal of Veterinary Research
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• v.13 no.2
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• pp.147-160
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• 1973

The present experiments proposed to pass judgement upon the suitability as the second intermediate host of Clonorchis sinensis, of three kinds of fresh-water fish by having them infected with the cercaria of Clonorchis sinensis and then observing the penetrating ability of the cercaria, and maturity, the process of degeneration and extinction, and infectivity of the metacercaria of Clonorchis sinensis. The following is a brief summary of the leading facts gained through the experiments; 1. P. parva was easily subject to invasion of the cercaria, A. signifer was much less subject to the invasion, and finally A. asmussi was hard to invade. And the infectivity of the cercariae was in proportion to their penetrating ability mentioned in the above. 2. The examination of the cercariae after having three kinds of fresh-water fish infected with them disclosed that 24 hours after the infection, all of the cercariae formed their cysts in muscle and the metacercariae kept growing, and that 7 days later the metacercariae were found folding their bodies twice, and that in 15 days the characteristic structure of the metacercariae was complete and they made a vigorous rotary movement intermittently. 3. Then the metacercariae came to a state of maturity and beyond this stage some metacercariae in P. parva started the process of degeneration and extinction in 133 days; some in A. asmussi, in 140 days; and A. signifer, in 70 days. As more days elapsed, their degeneration and extinction increased in number, and in 269 days all of them in A. signifer became dead while those in A. asmussi were all dead in 460 days. However almost all of them in P. parva survived even after 770 days. The results shown above revealed that P. parva was the most suitable as the second intermediate host among three kinds of fresh-water fish and that A. signifer and A. asmussi were not quite recommendable as the second intermediate host. The ability of the cercaria to invade fresh-water fish, and life span of the metacercaria within fresh-water fish vary outstandingly according to species of fresh-water fish. An explanation as to the mechanism must wait as the subject to be further pursued.

• Parasites, Hosts and Diseases
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• v.53 no.3
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• pp.289-298
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• 2015

The infection status of freshwater fish with digenetic trematode metacercariae was examined in water systems of Hantangang and Imjingang (River), the Republic of Korea. A total of 877 (594 from Hantangang and 283 from Imjingang) fishes were examined by the artificial digestion methods. Clonorchis sinensis metacercariae were detected in 7 (1.2%) fishes (in 3 spp.) from Hantangang in Cheorwon-gun, Gangwon-do, and 40 (14.1%) fishes (in 7 spp.) from Munsancheon in Paju-si, Gyeonggi-do. The average densities were 1.9 and 35.6 per fish infected, respectively. Metagonimus spp. metacercariae were detected in 312 (52.5%) and 113 (39.9%) fishes from Hantangang and Imjingang, and their average densities were 47.5 and 9.6 per fish infected, respectively. Centrocestus armatus metacercariae were found in 161 (27.1%) and 70 (24.7%) fishes from Hantangang and Imjingang, and their average number per fish infected was 694 and 82, respectively. Echinostoma spp. metacercariae were detected in 50 (8.4%) and 94 (33.2%) fishes from Hantangang and Imjingang, and their average densities were 9.6 and 23.1 per fish infected, respectively. The infection status of fishes with metacercariae of Stephanoprora spp., Diplostomum spp., Clinostomum complanatum, Metorchis orientalis, and Metorchis taiwanensis were analyzed by surveyed regions. Conclusively, it was confirmed that C. sinensis metacercariae were quite commonly detected in fishes from Munsancheon but rarely from other localities, whereas the metacercariae of other digenetic trematodes were relatively prevalent in fishes from water systems of Hantangang and Imjingang in Korea.

• Parasites, Hosts and Diseases
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• v.52 no.4
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• pp.399-412
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• 2014

The infection status of zoonotic trematode metacercariae was investigated in a total of 2,293 freshwater fish collected from 11 rivers or streams in 9 administrative regions of Gangwon-do, Korea for 5 years (2009-2013). All fish were collected by netting methods and examined using the artificial digestion methods. Clonorchis sinensis metacercariae were detected in 4 fish species, i.e., Pungtungia herzi, Squalidus japonicus coreanus, Acheilognathus rhombeus, and Ladislabia taczanowskii, from only Hantangang in Cheorwon-gun. Metagonimus spp. metacercariae were found in 1,154 (50.3%) fish and their average number per infected fish was 55.8. Among the positive fish species, especially Tribolodon hakonensis from Namdaecheon in Yangyang-gun and Plecoglossus altivelis from Osipcheon in Samcheok-si were most heavily infected. Centrocestus armatus metacercariae were detected in 611 (26.7%) fish and the average metacercarial burden per infected fish was 1,032. Two chub species, Zacco platypus and Zacco temminckii were highly and heavily infected with C. armatus metacercariae in almost all regions surveyed. Echinostoma spp. metacercariae were also found in 24 fish from a few localities, but their numbers per fish infected were very low. From the above results, it is confirmed that the metacercariae of intestinal flukes, especially Metagonimus spp. and C. armatus, were heavily infected, while C. sinensis metacercariae were rarely found in fish from Gangwon-do, Korea.

• Parasites, Hosts and Diseases
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• v.59 no.3
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• pp.265-271
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• 2021

We surveyed on the infection status of zoonotic trematode metacercariae (ZTM) in freshwater fishes from Soyang-cheon (a branch stream of Mangyeong-gang) in Wanju-gun, Jeollabuk-do, the Republic of Korea. A total of 927 fishes were individually examined with the artificial digestion method during 2013-2015 (462 fish in 15 spp.) and 2018-2019 (465 fish in 25 spp.). Clonorchis sinensis metacercariae were detected in 207 (31.4%) out of 659 fishes in 14 positive fish species (PFS), and their mean intensity was 114 per fish infected (PFI). Metagonimus spp. metacercariae were found in 302 (37.4%) out of 808 fishes in 21 PFS, and their mean intensity was 12 PFI. Centrocestus armatus metacercariae were detected in 222 (59.0%) out of 376 fishes in 12 PFS, and their mean intensity was 383 PFI. Echinostoma spp. metacercariae were found in 139 (22.1%) out of 628 fishes in 10 PFS, and their mean intensity was 7 PFI. Clinostomum complanatum metacercariae were detected in 14 (6.5%) out of 214 fishes in 4 PFS, and their mean intensity was 2.4 PFI. Metorchis orientalis metacercariae were detected in 36 (13.5%) out of 267 fishes in 5 PFS, and their mean intensity was 4.3 PFI. Conclusively, the prevalence and infection intensity of ZTM is generally not so high in fishes from Soyang-cheon. However, those of C. sinensis metacercariae are more or less higher in 2 fish species, Pungtungia herzi and Sarcocheilichthys variegatus wakiyae.

• Toxicological Research
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• v.17
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• pp.79-82
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• 2001

The infection of liver flukes, Clonorchis sinensis (CS) and Opisthorchis viverrini (OV), has been known as a risk factor to induce cholangiocellular carcinoma (CCC) in human living in the endemic area, providing promoting effect on the liver initiated by chemical carcinogens. The present study evaluated the relationship between the dosage level of dimethylnitrosamine (DMN) and the infection load of CS in the neoplastic development by histopathological examination of the treated hamsters. To evaluate the effects of DMN, different doses of DMN ranging from 0 to 25 ppm were administered to hamsters with 20 CS metacercariea. For the risk assessment of the infection load, 0, 5, 15, 50 CS metacercariae were respectively infected with 12 ppm DMN. The mortality was closely related to the infection load rather than the concentration of DMN. The infection of CS clearly promoted the induction of CCC even at dose level of 6 ppm DMN. Only five metacercariae were enough to promote CCC induction at the concentration of 12 ppm DMN.

• Parasites, Hosts and Diseases
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• v.60 no.2
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• pp.79-96
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• 2022

The infection nature of Clonorchis sinensis metacercariae (CsMc) in freshwater fish hosts is closely related to the transmission of human clonorchiasis. This article reviewed the infection characteristics of CsMc in freshwater fish in the Republic of Korea (Korea). The status of CsMc infection was examined in a total of 17,792 cyprinid fish of 49 species in 9 water systems, which included Hantan-/Imjin-gang, Han-gang, Geum-gang, Mangyeong-gang, Yeongsan-gang, Tamjin-gang, Seomjin-gang, Nakdong-gang, and streams in the east coastal areas from 2010 to 2020. The infection status of CsMc was examined according to cyprinid fish species and water systems, after which analyzed by endemicity and susceptibility index. The high endemicity was shown in the cyprinid fish from 3 regions (6.1%) in the upper reaches of Nakdong-gang, such as Banbyeon-cheon (stream), Yongjeon-cheon, and Wi-cheon. The moderate levels were observed in fishes from 8 regions (16.3%), and low endemicity was shown in fishes from 20 regions (40.8%). No CsMc were detected in fish from 18 regions (36.7%). The susceptibility of CsMc in index fish, Puntungia herzi, was found to be a reliable index without examination of other fish species. CsMc infection rates were closely related to subfamily groups in the cyprinid fish hosts in a highly endemic area. In Korea, a total of 58 fish species in 10 families has been listed as the second intermediate hosts for C. sinensis. This review provides several novel features of CsMc infection and clarifies the species of second intermediate freshwater fish host in Korea.

• Parasites, Hosts and Diseases
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• v.53 no.1
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• pp.65-75
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• 2015

Clonorchis sinensis habitating in the bile duct of mammals causes clonorchiasis endemic in East Asian countries. Parkin is a RING-between-RING protein and has E3-ubiquitin ligase activity catalyzing ubiquitination and degradation of substrate proteins. A cDNA clone of C. sinensis was predicted to encode a polypeptide homologous to parkin (CsParkin) including 5 domains (Ubl, RING0, RING1, IBR, and RING2). The cysteine and histidine residues binding to $Zn^{2+}$ were all conserved and participated in formation of tertiary structural RINGs. Conserved residues were also an E2-binding site in RING1 domain and a catalytic cysteine residue in the RING2 domain. Native CsParkin was determined to have an estimated molecular weight of 45.7 kDa from C. sinensis adults by immunoblotting. CsParkin revealed E3-ubiquitin ligase activity and higher expression in metacercariae than in adults. CsParkin was localized in the locomotive and male reproductive organs of C. sinensis adults, and extensively in metacercariae. Parkin has been found to participate in regulating mitochondrial function and energy metabolism in mammalian cells. From these results, it is suggested that CsParkin play roles in energy metabolism of the locomotive organs, and possibly in protein metabolism of the reproductive organs of C. sinensis.