• Parasites, Hosts and Diseases
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• v.33 no.3
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• pp.147-154
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• 1995

A new haplosplanchnid cercaria, Cercaria kuwaitae VI sp. n., was found in the prosobranch snail Cerithidea cincingulata in the Kuwait Bay Details are presented on the morphology and behavior of the cercaria and the encystment process. The new cercaria is a biocellate, distome, with a prominent single sac-like intestinal cecum extending well posterior to the ventral sucker and develops in simple sporocysts. It differs from known haplosplanchnid cercariae in the absence of finger-like processes on the tail, and the presence of V-shaped excretory vesicle extending beyond ventral sucker and the presence of cervical glands. The surface topography of the cercaria and its sporocyst is examined by scanning electron microscopy. This is the first haplosplanchnid cercaria to be described from a Cerithidea species.

• Parasites, Hosts and Diseases
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• v.25 no.1
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• pp.69-82
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• 1987

The prevalences of the cuke belonging to genus Metagonimus hove been reported along the upper stream of inhabitants by several workers since 1980, however the taxonomical problems of the fluke was not yet settled. The larval flukes; cercaria and metacercaria as well as their intermediate hosts, and adult were studied in order to identify the Mepagonimus in the areas. The results obtained are summarized as follows: 1. The snails, Semisulcospira globus were collected (rom the three different localities along the upper stream of the River. The cercariae were found from 125(7.2%) out of 1,730 snails by natural emerging method, and were identified into 5 species including Metagenimus sp. (3.7%), Pseudexorchis major(1.4%), Cercaria nipponensis (0.9%), Cercaria incerpa(0.6%), and Cercaria yoshidae(0.6%). Cercariae of Metagonimus species had four to dye oral spines on its anterior of the first line. 2. The cercariae of Metagonimus were experimentally exposed to goldfish. nfection rate was 22.9% out of 105 goldfish, and the encysted metacercariae were found in fins(86.7%) and on scales (13.7%) of the fishes, but not in their muscle, head or visceral organs. 3. Seven species of ask were caught in the Daecheong Reservoir and the upper stream. Infestations with metacercaria of Metagonimus were found 100% in Opsariichtys widens and the parasitized numbers of the metacercariae were observed from 250 to 2,400 per fish. In the upper stream, Zacco termmincki, Z. platypus and Pseudogobio esocinus were infected 100% with the metacercaria, on the other hand, the fishes caught in the reservoir showed the lower infestation rates, and a few metacercariae found in the fishes Carassius carassius and Cyprinus carpio in the reservoir and the stream. The majority of metacercariae was detected only on the scales of fishes. 4. In order to know the infectivity and the distribution patterns in the intestine of hosts, rats and dogs were infected with the metacercariae obtained from O. bidens and Z. platypus. In addition the metacercariae obtained from Z. temmincki, P. esocinus and goldfish were given to the rats. The recovery rates of the worms in the small intestine of dogs were higher (63.3~65.8%) than those of the rats (3.5~31.6%). The flukes were found mostly in the middle and the lower part of small intestine of the rats and the dogs, but no worm was collected in the upper part of the intestine of rats. 5. The sixte of adult flukes varied by the hosts. In the adult cukes, oral sucker was smaller than ventral sucker, and the right and left testes were located diagonally, the uterine tubules circled around the upper left testis. The average egg sixte was $29.1{\times}1.7{\mu\textrm{m}}$. According to the above results, the cukes belonging to genus Metagonimus distributed along the Geum River was concluded to be identical with Miyata type of M. yokogawai as that Saito had proposed.

• Parasites, Hosts and Diseases
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• v.21 no.1
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• pp.6-10
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• 1983

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, asking with rod and lino, and using the a 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 brfvicorpus Mori, the fat minnow, Morose 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 sweet-fish, Plecoglossus aztivelis (Temminck et Schlegel) were examined. Four species of the metacercariae, Exorchis eviformis, Metacercaria hasegawai, Metorchis orientalis and undetermined larvae were found. Of these, the encysted larvae of the human intestinal fluke, Metagonimus yokegawai, 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 sweets;sh 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 was 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 wqs more heavily infested and the mean number of cysts per gram of flesh in Plecoglossus altivelis was 109.2. It was foung that infection with Metagonimus yokogawai os caused by consuming raw fresh-sater fish and brackish-water fish caught in the river Taechong, Kyungpook Province, Korea.

• 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.23 no.1
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• pp.79-86
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• 1985

In order to judge appropriately the suitability as the second intermediate host of Clonorchis sinensis, the present experiments were proposed to survey the metacercaria of C. sinensis in the fish host, Cuztriculus eigenmanni, in the 6eld, and to observe, by experimental infection of the fish with Clonorchis cercaria, the penetrating ability of the cercaria, maturity, the process of degeneration and extinction, and infectivity of the metacercaria. The following is a brie summary of the leading facts gained through the experiments. 1. All the ten fish (mean body weight $13.4{\pm}3.439$) which were caught in Ok-ku irrigation reservoir were in acted with the metacercariae and the average number of the metacercariae found in the fish body/gram was 4.55. 2. The Bish was easily subject to invasion of the cercaria, and the examination of the cercariae after having the fish infected disclosed that 5:l hours after the infection, all of the cercariae formed their cysts in muscle and the metacercariae kept growing, 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 made a vigorous rotary movement intermittently. 3. In the case of control fish, Pseudorasbora parka, both penetrating ability of the cercariae and the infective degree of the metacercariae to control host were stronger as compared with the 5sh host because that the control fish had higher suceptibility to C. sinensis. 4. Afterwards, the metacercariae in the fish host came to a state of maturity and beyond this stage some metacercariae started the Process of degeneration and extinction in as early as 30 days, and as more days elapsed, mortality of the metacercariae was not uniformly increased but difference of mortality appeared to be according to the individual of Ssh host. That is, in 390, 540 and 586 days, all of the metacercariae in the fish hosts became dead, meanwhile almost all of those found in the fish host of 596 days after the infection survived (mortality; 8, 51%) , Percentage of orally administered metacercariae developing to maturity in rabbit is 10.465 in the last case. 5. As the days were progressed the shapes of the metacercariae in the fish host tended to change from ellipsoid to almost round shapes, the length became shorter while the width was wider. The results shown above revealed that C. eigenmanni was, though it could not be proper host than p. larva. suitable as the second intermediate host in addition to our previous observation results.

• Journal of agricultural medicine and community health
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• v.7 no.1
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• pp.66-73
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• 1982

Paragonimus westermani is one of the most popular endemic parasitic diseases in Korea. The nation-wide prevalence survey were carried out by Gobayashi (1921) with sputum examination and by Walton and Chyu (1959) with the intradermal skin test respectively. Recent studies showed the decline of positive rate in intradermal skin test of the local inhabitants and also showed the less distribution of intermediate host. The fact seemed that caused by economic improvement of village people, decrease of intermediate host by increasing use of pesticides, becoming lower water level at streams and rivers and better irrigation and finally by better community health education etc. Gangwha area of Gyeonggi-Do was found out as an endemic area of Paragonimus westermani through some studies in the past, however, in the vicinity area of Gangwha, the study in Kyodong island (myon) was carried out in 1965 by Yun et al. Therefore author carried out the intradermal skin test for 2,380 students of primary, middle and high school in Kyodong island and Samsan island. The results showed as follows : 1) The positive rate of intradermal test for paragonimus westermani infection showed positive in 152 among 1,845 students (8.2%) in Kyodong island, and 21 among 637 students (3.3%) in Samsan island respectively. 2) According to grade levels, 49 among 973 students (5.0%) in primary school, 62 among 962 students (6.4%) in middle school and 53 among 445 students (11.9%) in high school showed positive rate. This showed the higher grade the higher positive rate. 3) Among these total 164 positive cases in the intradermal skin test, only in 3 cases eggs were found in sputum. 4) Finding out the intermediate host, only 28 crayfishes from Kyodong island and 12 from Samsan island were collected and examined for metacercaria infection, however, none of metacercaria was found. 5) As a control group, 2 primary schools from the main island were selected. In these schools from the sixth grade students showed positive rate of 4.8% in Naega primary school and 0% in Hajeom Primary school respectively. Those results showed much decrease than studies carried out in the past. 6) The survey for food habit showed that 15 among 1,274 students (1.2%) had experiences of eating raw intermediate host(crayfish) and 266 among 988 students (27.0%) ate cooked.

• 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.

• Parasites, Hosts and Diseases
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• v.30 no.1
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• pp.43-48
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• 1992

Paragonimus westermani is a common fluke in Uorea. The present study aimed to observe the cell mediated immune response in experimental paragonimiasis of mice. The mouse (BALB/c) was orally inoculated with 40 metacercariae of P. westermani from Cambaroides similis. During the infection (1, 2, 4, 6 weeks) of mouse, blastogenic response of splenic Iymphocytes to P. westermani adult antigen, metacercaria antigen, and PHA were observed. Sera from infected and noninfected mice added to normal mouse splenic Lymphocytes with or without PHA. The blastogenic response of splenic Lymphocytes to PHA was reduced after 1 week of infection. However after 6 weeks of infection, the response was restored to the control level. The blastogenic response of splenic Iymphocytes to P. westermani adult or metacercaria antigen increased significantly on 1 week after infection, and maintained up to 6 weeks after infection. The response of non-infected mice was suppressed by addition of the infected mouse serum. The present results suggested that cellular immunity was involved in P. westermani infected mice and that P. westermani anti.serum inhibited proliferation of T Iymphocytes.

• 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.35 no.3
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• pp.165-170
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• 1997

The present study was performed to analyze the infection status of trematode metacercariae in fishes caught from Chunamchosuchi (pond) located in Uichang-gun. Kyongsangnam-do. A total of 130 freshwater fish of 5 species was collected by a fish net and fish traps from November, 1995 to May, 1996. They were examined under a stereomicroscope after artificial digestion with pepsin-HCI solution. A total of 8 species or metacercaria, i. e. Clonorchis sinensis, Echinochnsnw japonicas, Cvathocotwle orientalis, Diplostomun sp.. Metorchis orientalis. Holostephcnw nipponicw, Exorchis oviformis and unidentified echinostome, was detected from them. The metacercariae of C. sinenesis were found in 8/20 (40.0%) Accnthorhodeus Qsmwsi, 20/20 (100%) Cutter breuiccudc, 31/45 (68.9) Cultriculus eigenmanni and 21/25 (84.0%) Pseunorasborc pronga, and the average number of metacercariae detected in each fish species were 1.9, 31.7. I5.3, and 73.0. From the above results, it was confirmed that fresh-water fishes from Chunamchosuchi (pond) were highly infected with metacercariae of avian trematode, i.e. C. orientolis, H. nipponicus. M. oui,entnlis, E. jcponicw and Diplostonum sp., and 4 species of fish. P. parvc, C. breuiccudn, C. eigenmnnni and A. asmussi, were infected with metacaecariae of C. sinensis.