• Parasites, Hosts and Diseases
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• v.31 no.4
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• pp.347-352
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• 1993

Six early third-stage larvae of Gnnthostoma nipponicum were recovered from the muscle of 376 loaches, Misgurnw anguiILicnudatus, imported from China. They were 614 × 114㎛ in average size, almost colorless except brownish intestine, and encircled by about 229 transverse rows of minute cuticular spines. Their head bulbs provided with 3 rows of hooklets, of which average number were 34.5 on the first, 36.7 on the second and 39.7 on the third. According1y, it is revealed that the Chinese loach is a natural second intermediate host of G. nipponicum and G. nipponicum has been distributed somewhere in China. This parasite may infect human when the imported loaches are consumed raw.

• Parasites, Hosts and Diseases
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• v.26 no.3
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• pp.207-214
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• 1988

The Hongcheon river system knows down through the Hongcheon area of Kangwon-do, and reaches to the Cheongpyeong "Dam in Kyonggi.do. Stool specimens from the inhabitants residing along the Hongcheon river basin were examined to detect infection rates of Metagonimus sp. , and the intermediate hosts were collected to detect larval stages. The results obtained were as follows: 1. Thirty-nine (33 males and 6 females) out of 529 (314 males and 215 females) inhabitants were infected with Metagonimus sp., showing a total positive rate of 7.4%. 2. In eight areas surveyed, the specimens from Kulji.ri of Bukbang-myon at the middle part of the river showed the highest positive rate of 26.9% (14 positives out of 52) (males; 38.2%), The specimens from Mogog-ri of Seo-myon at the downstream of the river showed a positive rate of 10.4%(13 positives out of 125) (males; 12.6%). The positive rates in other regions were less than 10%. 3. The density of the first intermediate host, Semisulcospira sp., was the highest in Kulji.ri of Bukbang-myon (10~20 snails per $m^2$), and the infection rate of Metagonimus cercariae in the snails was 10.7%(13 positives out of 121 snails). 4. The infection rate of Metagonimus metacercariae in Zacco platypus, the freshwater Bish favorably eaten raw by the inhabitants, was 68.25 (30 positives out of 44 fishes), and most metacercariae were detected under the scales (89.95). 5. Adult flukes were obtained from the small intestine of a rat, 15 days after infection with the metacercariae obtained from Z. platypus. These adult cukes were identified to be the same species as thcse obtained from human hosts. By this survey, new endemic areas of Metagonimus infection were discovered along the Hongcheon river basin and the main source of infection was the fresh water ash, Z. platypus.

• Parasites, Hosts and Diseases
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• v.29 no.2
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• pp.161-172
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• 1991

The complete life cycle of Echinostoma hertense has been maintained in the laboratory, using Lymnaea persia snails and Rana nigromaculata tadpoles as the first and second intermediate hosts. ICR mice was used as the definitive host. Within the egg of 5. hotense, the miracidium was fully matured in 13 days of incubation at $29~30^{\circ}C$. The miracidium was $93.8{\times}53.6{\;}{\mu\textrm{m}}$ in average size, covered with numerous cilia of $7~11{\;}{\mu\textrm{m}}$ length. The epidermal plates were arranged in 6-8-4-2 formula. The first generation rediae ($1.19{\times}0.27{\;}mm$ in average size) were observed in 14 days after miracidial challenge to the snails, and the second generation rediae ($1.40{\times}0.26{\;}mm$ in average size) in 30 days. The average sixte of the cercaria was $295.5{\times}145.0{\;}{\mu\textrm{m}}$. Their head crown was poorly developed, and collar spines were not yet observed. After a cercarial challenge to the tadpoles, all of the tadpoles became infected and the average worm recovery rate was 88.5%. The majority of the metacercariae (75.5%) were recovered from the muscle of the tadpole's posterior body and the rest (24.3%) from their gills. The metacercariae from the tadpoles were elliptical, and $167.7{\times}129.9{\;}{\mu\textrm{m}}$ in average size. The recovery rate of adults from the mice was difFerent by the age of the metacercariae grown in the tadpoles. The metacercariae younger than 5 hrs could not infect mice whereas those older than 6 hrs could infect mice. The recovery rate became higher as the metacercaria matured, with the peak recovery rate of 90.0 % at the metacercarial age of 9 days. Thereafter the recovery rate decreased to 55.0% at the age of 50 days. As shown by the above results, the whole life cycle of E. hcrtense has been completed in the laboratory. At least 55~58 days were required to maintain one egg-to-egg cycle of E. hortense.

• Weed & Turfgrass Science
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• v.5 no.2
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• pp.101-104
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• 2016

Curvularia leaf blight of creeping bentgrass (Agrostis stolonifera) putting green by caused Curvularia trifolii was observed in Hapcheon, Korea. In July to September 2014, curvularia leaf blight developed on leaf blades of creeping bentgrass as small water-soaked lesions that subsequently turned into dark-colored, necrotic spots. The spots were expanded and became gray, grayish-brown, or light brown, circular to oblong lesions with purple to dark brown borders that often were surrounded by a yellow halo. The necrotic lesions coalesced, became irregular in shape and caused tip or complete blighting of the leaves. Blighted leaf blades appeared grayish-white to tan. The fungus was identified by morphological characters and 16S rDNA sequencing as C. trifolii. Conidia of the pathogen were short, with predominantly 3-septa, straight or often curved, with end cells frequently paler than intermediate cells. Size of the 3-septate conidia in culture are $26{\sim}28{\times}11{\sim}12{\mu}m$. Pathogenicity of the fungus was proved by artificial inoculation on the host. This is the first report of C. trifolii causing leaf blight on creeping bentgrass in Korea.

• Parasites, Hosts and Diseases
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• v.27 no.3
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• pp.203-212
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• 1989

The development of Echinestcma cinetorchis in several snail species reared in laboratory aquaria was observed. The eggs from adult cukes collected from the intestine of rats were cultivated to miracidia, and exposed to Hippeutis sp. snails. Observations were made for cercarial shedding from the exposed snails. The cercariae shed from the snails were again exposed to several species of fresh water snails in order to observe metacercarial formation in the snails and their infectivity to final hosts. The results obtained in this study were as follows: 1. Twenty miracidia were exposed to each snail of Hippeutis sp. About 58.3% of the above snails (7 out of 12) were dead before shedding the cercariae, anti the remainder shed the cercariae for a period of 7 to 9 days before death. 2. Cercarial shedding from the infected snails started from the 25th day after the exposure to mi.acidia, and the total number of cercariae shed per snail was 684 in average (range; 482-904). 3. The sixte of refine developed in the infected Hippeutis sp. snails was 1$, 242{\times}214{\;}{\mu}m$ in average, and the number of rediae per snail was 350 in average (range; 120-510). 4. About 40 to 50 cercariae shed from the Hippeutis sp. snails were each exposed to several species of snails reared in the laboratory. The metacercarial formation was confirmed by dissecting the infected snails, 12 to 16 days after the infection. The infectivity to each snail species was 100% in Hippeutis sp. (recovery rate; 56.7%) and Radix auricuzaria coreana (recovery rate; 66.4%), 66.7% in Physa acute (recovery rate; 37.5%), and 50% in Cipangopaludina sp. (recovery rate; 8.0%), respectively. 5. The swimming cercariae attached first at the cephalo-podial part of the snails and then migrated to the mantle, internal organ s and hemocele areas to form the metacercariae. 6. Adult worms of E. cinetorchis were obtained from the rats infected with the metacercariae encysted in the experimental snails. Summarising the above results, it is suggested that the mud-snail (Cipangopaludina sp.) may play an important role as a source of human infection with E. cinetorchis in Korea, and that several species of fresh water snails are involved in the life cycle as a second intermediate host.

• Parasites, Hosts and Diseases
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• v.59 no.1
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• pp.83-88
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• 2021

Life cycle stages, including daughter sporocysts, cercariae, and metacercariae, of Parvatrema duboisi (Dollfus, 1923) Bartoli, 1974 (Digenea: Gymnophallidae) have been found in the Manila clam Ruditapes philippinarum from Aphae-do (Island), Shinan-gun, Jeollanam-do, Korea. The daughter sporocysts were elongated sac-like and 307-570 (av. 395) ㎛ long and 101-213 (av. 157) ㎛ wide. Most of the daughter sporocysts contained 15-20 furcocercous cercariae each. The cercariae measured 112-146 (av. 134) ㎛ in total length and 35-46 (av. 40) ㎛ in width, with 69-92 (av. 85) ㎛ long body and 39-54 (av. 49) ㎛ long tail. The metacercariae were 210-250 (av. 231) ㎛ in length and 170-195 (av. 185) ㎛ in width, and characterized by having a large oral sucker, genital pore some distance anterior to the ventral sucker, no ventral pit, and 1 compact or slightly lobed vitellarium, strongly suggesting P. duboisi. The metacercariae were experimentally infected to ICR mice, and adults were recovered at day 7 post-infection. The adult flukes were morphologically similar to the metacercariae except in the presence of up to 20 eggs in the uterus. The daughter sporocysts and metacercariae were molecularly (ITS1-5.8S rDNA-ITS2) analyzed to confirm the species, and the results showed 99.8-99.9% identity with P. duboisi reported from Kyushu, Japan and Gochang, Korea. These results confirmed the presence of various life cycle stages of P. duboisi in the Manila clam, R. philippinarum, playing the role of the first as well as the second intermediate host, on Aphae-do (Island), Shinan-gun, Korea.

• 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.

• Journal of Marine Life Science
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• v.3 no.2
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• pp.96-100
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• 2018

Clonorchis sinensis is a main parasite that infects humans by making freshwater fish as an intermediate host in South Korea. There are so many reports about the infestation status of Clonorchis sinensis metacercariae (CsMc) in freshwater fish living in the river, but there are a few studies of fish in the lake. In this study, we examined CsMc in Cyprinid fish sampled from Soyang Lake, Namyang Lake, Andong Lake and Chunchun Lake from 2016 to 2017. Metacercaria of trematodes were found from Hemiculter eigenmanni and Carassius auratus in Namyang Lake, and Zacco platypus and Opsarichthys uncirostris in Soyang Lake. As a result of PCR using Clonorchis sinensis specific primer sets, it was confirmed that the metacercariae from Hemiculter eigenmanni in Namyang Lake was CsMc. This study provides information on CsMc infestation status of Cyprinid fish in four lakes and it is the first report of CsMc infestation in Namyang Lake.

• Biomedical Science Letters
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• v.4 no.1
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• pp.65-72
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• 1998

Recently there have been frequent reports on human infection caused by the Diphyllobothridae in Korea. The adequate opportunities for Koreans to eat raw fish, the primary infection medium of cestodes and the human infection through drinking water by cyclops, the first intermediate host are believed to be main reasons for the infection. The first task of this study was to classify and diagnose the species by differentiating morphological characteristic between scolex and proglottids of cestodes. However, the initially available diagnosis was done with the patient's symptoms and the eggs obtained from his stool. It is important to differentiate the species by the eggs of Diphyllobothrium latum especially in that it can help get advance information for a more reliable analysis in the near future. The morphological and diagnostic results from proglottids and eggs of Diphyllobothrium latum, Diphyllobothrium latum parvum and Spirometra erinacei are as follows； In each kind of cestodes from the patient's stool, the shape and size of 50 eggs were measured. Eggs of Diphyllobothrium latum had an operculum and were ovoidal or ellipsoid to elliptical in shape. Eggs of Diphyllobothrium latum parvum were more ovoidal in shape and smaller in size than Diphyllobothrium latum. And eggs of Spirometra erinacei were asymmetrical in width and long and slender in shape. The average lengths and widths of Diphyllobothrium latum, Diphyllobothrium latum parvum and Spirometra erinacei were 61.4$\times$41.7 $\mu\textrm{m}$, 55.9$\times$41.4 $\mu\textrm{m}$ and 66.7$\times$36.4 $\mu\textrm{m}$, respectively. After the segments of each cestode were fixed, embedding and hematoxylin-eosin dyeing on a microtome-made specimen were done. The micrographs of the semicon's aceto-carmine dyed specimen showed that Diphyllobothrium latum and Diphyllobothrium latum parvum had a centrally-located genital gland and an opened uterine pore. The yolks were observed on both sides of proglottids and had a typical rosette pattern. Yet, Diphyllobothrium latum parvum was shown smaller than Diphyllobothrium latum in the micrograph. Proglottids of Spirometra erinacei displayed that the uterus was rolled spirally more than five to seven times, and connected successively to the seminal vesicle in the cirrus sac. Shown above, this study was performed to measure the size of eggs and analyze the morphological characteristics of proglottids and provided the measurements of three types of cestodes obtained by a light microscope.