• Parasites, Hosts and Diseases
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• v.21 no.2
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• pp.224-233
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• 1983

An experimental study was carried out to observe the susceptibility of several kinds of laboratory animals to Fibricola seoulensis infection, a diplostomatid fluke of mammals. The metacercariae were obtained from the viscera of the snakes, Natrix tigrina lateralis and 50~2,000 in number each was artificially fed to a total of 127 animals; albino rats, mice, dogs, cats, rabbits and chickens. After 3 days to 8 weeks the animals were sacrificed and the recovery rate of worms as well as their maturity was observed. The results are as follows: 1. The overall worm recovery rates throughout the experimental period was highest in albino rats (40.0%) followed by mice (33.9%), cats (20.9%), dogs (11.4%), rabbits (0.05%) and chickens (0%). However, the recovery rates in the same host decreased as infection progressed longer and variable by the amount of metacercariae given. 2. From albino rats and mice, the highest recovery rates were obtained in 1,000 and 200-metacercariae infection groups respectively, and it is considered that such amount should be the optimum dose for experimental infection of these animals. 3. The main location of F. seoulensis in experimental animals was small intestine especially the duodenum. 4. The maturity index (No. mature worms/ No. examined) was 100% in albino rats and mice, while only 22.7% or 0% in dogs or cats respectively. From the results, it is concluded that albino rats and mice are the most susceptible hosts for F. seoulensis infection among six kinds of laboratory animals examined.

• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.41-46
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• 1985

The therapeutic effects of praziquantel on Fibricola seoulensis infection were studied by experimental infection of albino rats with the metacercariae obtained from the snakes. Total 51 albino rats were infected each with 500 or 1, 000 meta cercariae in number through intragastric tubes. One or four weeks la er the rats were treated with 1, 5, 10 or 20 mg/kg single dose of prazipuantel and sacrificed after 3 days or 10-120 minutes to search for the worms in their small intestine. The worm recovery rate at 3 days after the treatment was 10.7 % in 1 mg/kg dose group and o. 03~0.2% in 5, 10 and 20 mg/kg groups, while that of untreated control was 51. 3%. The minimum effective dose to treat F. seoulensis infection in the rats is considered to be 5 mg/kg in single dose. By observing the distribution pattern of worms in the small intestine after the treatment, dislodgement of the worms from the duodenum, their normal habitat, to the lower portions was recognizable within as early as 10 minutes. The majority of worms was found to have descended to the ileo-caecal portion after 60-120 minutes.

• Parasites, Hosts and Diseases
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• v.28 no.4
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• pp.235-240
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• 1990

During an investigation on intestinal flukes of house rats in Yangyang-gun, Kangwon-do, a total of 6 species of trematodes belonging to 3 families; Echinostom-atidae (Echinostoma hortense, E. cinetorchis, E. revolutum and Echinoparyphium recurvatum), Diplostomidae (Fibricoza seoulensis) and Plagiorchiidae (Plagiorchis muris), were recovered from two adult rats. E. revolutum and E. recurvatum were new trematode faunae of rats in Korea. 5. revolutum had an elongated body, 5.3∼6.Omm long and 1.0∼1.3mm wide. The total number of collar spines was 35∼37 including 5 end group ones on each ventral corner. Its coiled uterus contained numerous eggs.5. recurvatum also had an elongated body, 3.5∼4.7 mm long and 0.50∼0.65 mm wide. It had total 45 collar spines including 4 end group ones. The uterus toras short with only a few eggs. It has been first confirmed by this study that E. revolutum and E. recurvatum are indigenously distributed among house rats in Korea. Kef lords: Echinostoma revolutum, Echinoparyphium recurvatum. new fauna. house rats, Yangyang-gun ( Kangwon-do )

• Parasites, Hosts and Diseases
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• v.22 no.1
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• pp.21-29
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• 1984

A scanning eletron microscopic study was performed to observe the tegumental surface of adult Fibricola seoulensis. The adult worms were collected from the small intestine of mice 5 days to 3 weeks after experimental infection with the metacercariae. The metacercariae were obtained from the viscera of the snakes, Matrix tigrina lateralis, by artificial digestion technique. The results were as follows: 1. The tegument of anterior body was covered with cobblestone-like cytoplasmic processes and that of posterior body showed finger-like processes. The posterior body had 4-5 large transverse wrinklings which formed many discontinued shallow rugae. 2. The entire surface of anterior body was regularly arranged with the spines of which tips diverged into 3 to 4 points. They were densely packed in anterior mid-median portion of dorsal surface where appeared a few spines indented upto 5 points. Farther laterally and posteriorly from this portion, the pointed spines were more sparse and became single tipped and extended to anterior one-third of posterior body, 3. The posterior surface of oral sucker was armed with 50-60 spines having 2-3 tips and ventral sucker also covered with such spines. On anteriormost dorsal surface arranged 60-70 spade-shaped spines. The tribocytic organ was armed with many stout recurved pile-like spines arranged radially. 4. There were 3 types of sensory papillae. The ciliated knob-like (Type I) papillae were almost bilaterally symmetrical in ventral and dorsal surfaces of anterior body, and abundant especially aroundbases of oral and ventral suckers, tribocytic organ, and in lateral margins of anterior body. About 24 non-ciliated round swellings (Type II) were observed around each lip of oral and ventral suckers. The plate-like elevated papilla without cilium (Type III) was found to distribute only in posterior body. These 3 types of papillae seem to be tangoreceptive and/or rheoreceptive in function when their morphology and distributions are considered.

• Parasites, Hosts and Diseases
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• v.22 no.1
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• pp.51-60
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• 1984

Two cases of natural human infection by Heterophyopsis continua (Heterophyidae) were identified by collection of adult worms in 1983 in Korea. And in order to know the source of infection a study on fish intermediate hosts was performed along the southwestern coastal areas. The cases were 21 and 50 year old males residing in southern coastal areas. They had the clinical complaints of non-specific gastrointestinal symptoms such as epigastric pain and one of them also complained the discharge of tapeworm segments. Praziquantel in single dose of 10~15mg/kg was given followed by purgation with magnesium salt and 2 and 46 specimens of H. continua were collected from the diarrheal stools. They said to have eaten raw ilesh of several kinds of brackish water fishes. The results of fish examination for metacercarial infection were as follows: I. Seventeen (663.0%) out of 27 perches (Lateolabrax japonicus) and 10 (29.4%) out of 34 gobies (Acantkogobius flavimanus) harboured the metacercariae but none of 42 mullets (Mugil cepkalus) were found to harbour them. 2. The average metacercarial density in perches was 55.1 and 18.7 per fish respectively. And the majority of the metacercariae were collected from the muscle of body portions in these fishes. 3. After the metaeercariae were experimentally fed to two rats and one young dog. two adult worms were recovered from the dog while none from the rats. These worms were also identified as H. continua. From the results it was concluded that the brackish water flshes which the human cases said to have eaten were the source of infection.

• Parasites, Hosts and Diseases
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• v.22 no.2
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• pp.181-189
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• 1984

The metacercariae of Echinostoma cineterchis (Trematoda: Echinostomatidae) were found infected in the loaches (Misgurnus anguillicaudatus) purchased from two local markets in Korea. Identification of the metacercariae was done after obtaining adult worms from experimentally infected albino rats. Brief course of worm development in rats was also observed up to 28th post-infection day. The results are as follows: 1. The metacercariae of E. cinetorchis were detected from 5 (10.9%) out of 46 loaches examined and the average metacercarial burden per infected loach was 34.4. They were always found from the posterior abdominal wall. 2. The worm recovery rate from 8 rats was 24.6% in average. It was observed that the rate decreased according to age of infection; from 40.7% after 6 days to 15.0% after 28 days. 3. The adult worms were morphologically characterized by the presence of head crown with derfally uninterrupted collar spines, 37-38 in number, and the tendency of migration or disappearance of testes. So that they were identified as Echinostoma cinetorchis Ando et Ozaki, 1923. 4. The development of worm was very rapid during 6-10 days after infection and became much slower thereafter. During the rapid worm growth the development of genital organs was more prominent than that of non-genital organs. From the results it is concluded that the loach is involved in the life cycle of E. cinetorchis in this country and may take a role for infection source to animals and man. It is also confirmed that migration or loss of testes is the distinct specific character of this echinostomatid fluke.

• Parasites, Hosts and Diseases
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• v.58 no.1
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• pp.67-72
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• 2020

Human infection with Echinostoma aegyptica Khalil and Abaza, 1924 (Trematoda: Echinostomatidae) is extremely rare. In this study, we confirmed E. aegyptica infection in 5 riparian residents living along the Mekong River in Savannakhet Province, Lao PDR. The patients revealed eggs of Opisthorchis viverrini/minute intestinal flukes, echinostomes, and other parasites in fecal examinations using the Kato-Katz technique. Following treatment with praziquantel 30-40 mg/kg and pyrantel pamoate 10-15 mg/kg in a single dose and purging with magnesium salts, adult specimens of various helminth species were collected. Among the trematodes, echinostome flukes of 4.5-7.6 mm in length (n = 134; av. 22.3 specimens per case) were of taxonomic interest and subjected in this study. The flukes were morphologically characterized by having total 43-45 collar spines arranged in 2 alternating rows (corner spines usually 5 on each side) and compatible with previous descriptions of E. aegyptica. The patients were mixed-infected with other helminths, so specific clinical manifestations due to this echinostome fluke were difficult to determine. The present paper describes for the first time human E. aegyptica infections in Lao PDR. This is the second report of human infection (2nd-6th cases) with E. aegyptica in the world following the first one from China.

• Parasites, Hosts and Diseases
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• v.36 no.3
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• pp.155-162
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• 1998

Two endemic foci of heterophyid infections were discovered in coastal villages of Puan-gun. Chollabuk-do, and Sachon-gun. Kyongsangnam-do, Korea. Fecal examina- tions were performed on 153 inhabitants of Puan-gun and 138 of Sachon-gun, using cellophane thick smear and formalin-ether sedimentation technique. The helminth egg and/or protozoan cyst positive rate was 21.5% (33/153) in Puan-gun and 39.1% (54/138) in Sachon-gun. In Puan-fun, the egg Positive rate of heterophyids was the highest, 17.6%, and that of other parasites was 0.7-2.6% by parasite species. In Sachon-gun, that of heterophyids wa's 18.8%, followed by Clonorchis sinensis (12.3%). and other parasites (0.7-5.OBEI . Twenth-two (Puan-gun) and six (Sachon-gun) heterophyid egg Positive cases were treated loth praziquantel, and adult flukes were collected from their diarrheic stools. A total of 3,284 adult flukes of Heterophyes nocens was collected from all of the 22 patients treated in Puan-gun (3-778 individually) , and other trematodes were also collected from 2- 15 patients; Ftgidiopsis sumac, Stellcntchcsmus JcEcctus, Metogoninus Wokogaupci, M. miyntci, Stictodora Juscnta, Heterophwopsis continua, Acnnthopcrwphium kurognmo, and GWmnophaELoines seoi. In Sachon-gun, M. yokognwci (3,007 specimens), H. nocens (120), aud S. falcatus (46) were collected from 5 of 6 treated patients, and H. continuo and 5. tan each from one patient. The present study revealed that heterophyid flukes, especially If. nocens and M. Wokofowai, are prevalent in the southern and western coastal areas of Korea where fresh and/or brackish water fishes are popularly eaten raw.

• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.24-32
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• 1985

The worm development and egg laying pattern of Echinostoma hortense (Trematoda; Echinosto-matidae) were studied in albino rats and the brief clinical course was observed in human volunteers. A total of 21 rats were infected with 20~69 metacercariae each and two humans were with 7 and 27 metacercariae, which were collected from the loaches. For recovery of worms, the rats were sacrificed at irregular intervals from the 6th to 150th day after infection and the human volunteers were treated with praziquantel and purged with magnesium salt on the 26~27th day. The stools of the rats and humans were examined for the eggs. The results were as follows: 1. The worm recovery rate from the rats was not affected by the increase of infection time but varied individually; 9.1~50.0% (31.1 % in average). From humans, 14.3% and 37.0% (32.4% in average) of challenged were recovered. 2. In the rats, it was revealed that the worms rapidly grew for the first 14 days to become 7.59mm in average length and 1.17mm in average width but the growth became much slower thereafter until the 150th day; 7.95mm in length on the 21 th day, 9.04mm on the 28th day, 10.21mm on the 49th day and 12. 62mm on the 150th day. During the early stage of infection, the growth of genital organs (male or female) was expressed as sigmoid curves whereas non-genital organs (such as suckers) was simply as straight lines. 3. The prepatent period of this fluke was 10~12 days in the rats and 16~17 days in men. After the start of oviposition, the egg production by the worms remarkably increased, reached maximum on the 32~33th day, followed by decrease thereafter. The maximum value of E.P.G./worm was 390. 4. The major subjective symptoms in human volunteers were abdominal pain and diarrhea during the early stage of infection. The results show that human is as susceptible as the rats to E. hortense infection and the amount of egg production in the rats is greatly affected by the age of worms.