• Parasites, Hosts and Diseases
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• v.32 no.3
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• pp.149-156
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• 1994

An epidemiological study fur the Intestinal trematode infection of the villagers was done In Koje-myon, Kochang-gun, Kyongsangnam-do, Korea in March, 1994. Of 116 stool specimens examined, total helmlnthic ova positive cases were 13 (11.2%) and cumulative ova positive cases 21 (18.1%): Echinostoma hortense 11 cases (9.5%), Metngonimus sp. 6 cases (5.2%), and Clonorchis sinensis 4 cases (3.4%). After the treatment and purgation, variable numbers of E. hokene, 6 to 227 per person, were collected from 7 echlnostome egg Positive cases, together with M. tokohoshii In 6 cases. Three adult flukes of E. cinetorchis were collected from one person and one Stellantchasmw jnlcatus was recovered from another case. This mountainous village was proved to be one of the endemic foci of echlnostomlasis In Korea.

• Parasites, Hosts and Diseases
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• v.57 no.3
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• pp.273-281
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• 2019

The infection status of digenetic trematode metacercariae (DTM) was investigated in fishes from 2 representative visiting sites of migratory birds in Gyeongsangnam-do, the Republic of Korea (Korea). A totaly 220 freshwater fishes (7 species) were collected from Junam-jeosuji (reservoir), and 127 fishes (7 species) were also collected from Woopo-neup (swamp) in June and October 2017. As the control group, total 312 fish (22 spp.) from Yangcheon in Sancheong-gun, Gyeongsangnam-do were also collected in June and October 2017. All fishes collected in 3 sites were examined with the artificial digestion method. In the fishes from Junam-jeosuji, more than 4 species, i.e., Clonorchis sinensis, Echinostoma spp., Diplostomum spp. and Cyathocotyle orientalis, of DTM were detected and their endemicy was very low, 0.70. More than 6 species, i.e., C. sinensis, Echinostoma spp., Metorchis orientalis, Clinostomum complanatum, Diplostomum spp. and C. orientalis, of DTM were found in the fishes from Woopo-neup, and their endemicy was low, 5.16. In the fishes from Yangcheon, more than 8 species, i.e., C. sinensis, Metagonimus spp., Centrocestus armatus, C. complanatum, C. orientalis, M. orientalis, Echinostoma spp., and Diplostomum spp., of DTM were detected, and their endemicity was relatively high, 95.48. The percentages of avian trematode metacercariae (ATM) were 99.6% and 94.7% in fishes from Junam-jeosuji and Woopo-neup whereas it was 74.1% in the control site, Yangcheon. The above findings suggested that migratory birds partly affect in endemicity of DTM in the fish in the 2 visiting sites in Gyeongsangnam-do, Korea.

• Parasites, Hosts and Diseases
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• v.59 no.1
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• pp.47-53
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• 2021

Echinostoma mekongi was reported as a new species in 2020 based on specimens collected from humans in Kratie and Takeo Province, Cambodia. In the present study, its metacercarial stage has been discovered in Filopaludina martensi cambodjensis snails purchased from a local market nearby the Tonle Sap Lake, Pursat Province, Cambodia. The metacercariae were fed orally to an experimental hamster, and adult flukes were recovered at day 20 post-infection. They were morphologically examined using light and scanning electron microscopes and molecularly analyzed by sequencing of their mitochondrial cox1 and nad1 genes. A total of 115 metacercariae (1-8 per snail) were detected in 60 (60.0%) out of 100 Filopaludina snails examined. The metacercariae were round, 174 ㎛ in average diameter (163-190 ㎛ in range), having a thin cyst wall, a head collar armed with 37 collar spines, and characteristic excretory granules. The adult flukes were elongated, ventrally curved, 7.3 (6.4-8.2)×1.4 (1.1-1.7) mm in size, and equipped with 37 collar spines on the head collar (dorsal spines in 2 alternating rows), being consistent with E. mekongi. In phylogenetic analyses, the adult flukes showed 99.0-100% homology based on cox1 sequences and 98.9-99.7% homology based on nad1 sequences with E. mekongi. The results evidenced that F. martensi cambodjensis snails act as the second intermediate host of E. mekongi, and hamsters can be used as a suitable experimental definitive host. As local people favor to eat undercooked snails, these snails seem to be an important source of human infection with E. mekongi in Cambodia.

• Parasites, Hosts and Diseases
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• v.47 no.3
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• pp.311-314
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• 2009

A total of 1,498 small mammals (rodents and insectivores), including Apodemus agrarius (n= 1,366), Crocidura lasiura (54), Mus musculus (32), Micronytus fortis (28), Eothenomys regulus (9), Micronys minutes (6), and Cricetulus triton (3), were live-trapped in Gyeonggi-do (Province) (Paju-si, Pocheon-gun, and Yeoncheon-gun) near the demilitarized zone (DMZ) from December 2004 to September 2005. A. agrarius was found to be infected with 3 species of echinostomes (Echinostoma hortense, Echinostoma cinetorchis, and Euparyphium murinum), while C. lasiura was infected with 1 species (Echinochasmus japonicas) of echinostome. Other mammals were free from echinostome infections. Total 16 E. hortense were detected in 7 (0.5%) mice, 9 E. cinetorchis from 5 (0.4%), and 3 E. murinum from 2 (0.1%) out of 1.366 A. agrarius examined. E. japonicus was found only in 1 (1.9%; total 3 specimens) C. lasiura. These results demonstrate that A. agrarius and C. lasiura, inhabiting near the DMZ of Gyeonggi-do serve as the natural definitive hosts for several species of echinostomes, although their infection rates are low. This is the first record of natural infections of A. agrarius with E. cinetorchis and C. lasiura with E. japonicus in the Republic of Korea.

• Biomedical Science Letters
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• v.5 no.1
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• pp.109-118
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• 1999

The relationship between the intestinal histopathology and number and position of intraepithelial lymphocytes (IEL) was observed chronologically in the small intestine of rats experimentally infected with Echinostoma hortense. Sprague-Dawley rats were orally infected with 200 metacercariae obtained from Misgurnus anguillicaudatus. The rats each were sacrificed on the week 1, 2, 4, 6, 8 post-infection (PI) and samples of the intestine in the part of duodenum and jejunum were taken. The samples were stained with Hematoxylin-eosin and Giemsa. The intestinal histopathology was the severest after the week 1 PI and characterized by villous atrophy, crypt hyperplasia and decrease of villus/crypt(v/c) ratio, which continued until the week 8 Pl. The number of IEL dramatically decreased during the week 1 PI, but increased gradually thereafter with a slight decrease on the week 8 PI. In control rats, the great majority of the IEL were located at the basal region of the epithelium. During the early stage of infection, however, we found a considerable proportion of IEL to moved to the intermediate or apical regions of the epithelium. From the above results, it is sugested that the change of IEL number and position during the course of E. hortense infection should be closely related to the progression and recovery of the intestinal histopathology.

• 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.

• Biomedical Science Letters
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• v.6 no.2
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• pp.93-100
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• 2000

The change in mean absorbance values for IgA/IgE in rats and mice infected with Echinostoma hortense metacercariae was studied from the 2nd week to the 8th week after infection. Serum and intestinal luminal content (ILC) levels of IGA/IGE were measured by enzyme-linked immunosorbent assay(ELISA). The mean absorbance values obtained from IgA in the rats' ILC increased from the 2nd week to the 8th week after infection. The peak value (0.47$\pm$0.01) appeared in the 8th week. The mean absorbance values of IgE in the rats' ILC didn't increase significantly (p>0.05). The worm recovery rate decreased at a slower, pace after, infection. The duration in which the peak value of IgA in rats' ILC appeared was similar to that in which the worm recovery rate declined significantly. Serum levels of IgA/IgE in mice increased gradually from the 2nd week after infection. The peak value (0.45$\pm$0.01) of IgA appeared in the 8th week, and that (0.23$\pm$0.02) of IgE appeared in the 7th week after infection. The ILC level of IgA in mice continued to increase after infection, and reached its peak in the 8th week. The change in IgA/lgE in the serum and IgA in the ILC of mice was inversely related to worm recovery rate. As a result of this experiment, it is supposed that IgA/IgE may play an important role in the expulsion of Echinostoma hortense.

• 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.58 no.1
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• pp.73-79
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• 2020

Echinostoma revolutum is a zoonotic food-borne intestinal trematode that can cause intestinal bleeding, enteritis, and diarrhea in human and birds. To identify a suspected E. revolutum trematode from a red-crowned crane (Grus japonensis) and to reveal the genetic characteristics of its mitochondrial (mt) genome, the internal transcribed spacer (ITS) and complete mt genome sequence of this trematode were amplified. The results identified the trematode as E. revolutum. Its entire mt genome sequence was 15,714 bp in length, including 12 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes and one non-coding region (NCR), with 61.73% A+T base content and a significant AT preference. The length of the 22 tRNA genes ranged from 59 bp to 70 bp, and their secondary structure showed the typical cloverleaf and D-loop structure. The length of the large subunit of rRNA (rrnL) and the small subunit of rRNA (rrnS) gene was 1,011 bp and 742 bp, respectively. Phylogenetic trees showed that E. revolutum and E. miyagawai clustered together, belonging to Echinostomatidae with Hypoderaeum conoideum. This study may enrich the mitochondrial gene database of Echinostoma trematodes and provide valuable data for studying the molecular identification and phylogeny of some digenean trematodes.

• Proceedings of the Malacological Society of Korea Conference
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• 1999.11a
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• pp.9-9
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• 1999