The echinostomatid metacercariae encysted in the gill of the fresh water fish, Pseudorasbora parva were identified through obtaining adult worms after experimental infection to mice. In addition, a brief course of worm development and maturation was observed in this experimental host. The results were as follows: The echinostomatid metacercariae were elliptical, golden yellow, 0.073-0.078 mm long and 0.054-0.065 mm wide. Their head portions were characterized by the presence of a head crown armed with collar spines of total 24 in number and interrupted at the mid-dorsal side of the oral sucker. The average rate of worm recovery from 12 mice (on the 1-21th postinfection days) was 19.4 percent and the rate revealed no decrease in accordance with the increase of infection duration. The worms were collected chiefly from the lower part of the small intestine. After the infection, their sexual maturation was attained in 5 days and their growth in size nearly completed in 7 days. The early growth curve of genital organs was S shape while that of nongenital organs was C form. In 5 day old worms, l or 2 eggs were found from their uteri and the stools of mice revealed echinostomatid eggs from the 5-6th postinfection day. The 7 day old adult worms were ovoid in shape, 0.54-0.69 mm long and 0.29-0.34 mm wide, and characterized by a well developed head crown with 24 collar spines and vitelline follicles distributed from the acetabular level down to the posterior end of body. Based on these characters they were identified to be Echinochasmus japonicus Tanabe, 1926. From these results, it is verified that P. parva is one of the second intermediate hosts of E. japonicus in Korea.
parasitology-helminth-trematoda ; Echinochasmus japonicus ; metacercaria ; Pseudorasbora parva

The author studied the infection rates of Clonorchiis sinensis in the inhabitants of Kyungpook Province, and surveyed infestation rates of Clonorchis metacercarias in the twelve kinds of fresh water fishes for the purpose of the eradication. plan of clonorchiasis of Kyungpook Province. The examination was continued from April 1960 to October 1962 with 24,252 inhabitants ranging from four months to over sixty aged. All the family were tested intradermally with Clonorchis antigen and then confirmed the eggs by M.G.L. technique. The results of the examination were summarized as follows. I. The infection rate of the inhabitants; In the people tested, 27.7 percent was infected with Clonorchis sinensis. There were no remarkable differences in the infection rates among each Districts; River side inhabitants(Yungchun-Gun 23.6 percent, Andong-Gun 27.4 percent), paddy field inhabitants(Yungchun- Gun 23.6 percent, Sangchu-Gun 29.1 percent) and mountain side inhabitants (Chungsong-Gun 23.8 percent, Yungyang-Gun 27.7%). However, the infection rates of the river side peoples were slightly higher than that of the districts far from the river. The infection rate of the male was 34.98 percent (4 ,628 out of 12,230), while the female was 18.96 percent (2090 out of 11022). The maximum infection rate of the male group was observed in the 35-39 age group (73.8 %) and in female, 55-59 age group (34.l percent) respectively, however it was gradually decreased in the senile group. II. The infection rates of the family group; Those infected in both husband and wife were 28 percent(357 out of 1,289), husband only was 52 percent (672 out of 1,289) and wife only was 4 percent (50 out of 1,289). The children of the infected parents revealed higher morbidity than that of the non-infected parents. The children of the infected father revealed much morbidity than that of the mother's side. On the contrary, children's morbidity rate of the infected widow was higher than that of the widower. III. The infestation rates of fresh water fishes; The metacercaria of Clonorchis sinensis was found in the flesh exclusive of the Misgurnus anguillicaudatus and Zacco platypus in the 11 kinds of fresh water fishes. The maximum infestation rate of 55.8 percent was revealed at Pseudorasbora parva and next to it was Sarcocheilichthys wakiyae of 5l.7 percent. The number of metacercaria in flesh was decreased as compared to the previously examined level.
parasitology-helminth-trematoda-Clonorchis sinensis ; epidemiology ; Misgurnus anguillicaudatus ; Zacco platypus ; Sarcocheilichthys wakiyae ; Pseudorasbora parva

Since the pattern of the frequency distribution of a parasite within a host showed an overdispersed pattern, various statistical models such as Poisson, negative binomial and lognormal distributions have been applied on the population dynamics in host-parasite relations. The observed data on the number of metacercariae of Clonorchis sinensis in a suitable intermediate host, Pseudorasbora parva which were collected from an endemic area, Juk-Rim River, Kim-Hae Goon, South Kyong-Sang Do were applied on the statistical models. The results obtained are as follows: By the calculation of the raw data, 258(94.9 percent) out of 272 fish showed positive to the metacercarial infection of C. sinensis. The mean number of metacercaria in a fish was 335.1. The standard deviation was 250.6 and the mode was observed between 250 and 299. The frequency distribution pattern of metacercariae of C. sinensis within the fish host in surveyed area was fitted to the lognormal distribution (0.05 parasitology-helminth-trematoda ; Clonorchis sinensis ; metacercaria ; Pseudorasbora parva ; frequency distribution ; host

The present work was to observe the wormicidal effects of the external mucous substance of Carassius carassius and Pseudorasbora parva on cercaria, metacercaria (liberating) and adult of Clonorchis sinensis. The mucous substance which was extracted by ether was separated into various spots on the silica gel thin layer chromatography and separated into various fractions in the silica gel column chromatography, using petroleum ether(30 percent) and chloroform(70 percent) as solvent. R(f) 0.952 value of the silica gel thin layer chromatography and the first fraction (reddish yellow) frorn the silica gel column chromatography of the ether extracts from C. carassius had the wormicidal effect on all of the developing stages of C. sinensis. Cercaria was killed within 14 minutes, metacercaria within 27 minutes and adult 2.5 hours by the first fraction. But in the normal saline solution (control) and in the other fraction, cercaria and metacercaria were alive more than 24 hours and adult more than 72 hours. The extracts from the mucous substance of P. parva that is well penetrated by cercaria had no wormicidal effect on them.
parasitology-helminth-trematoda ; clonorchiasis-Clnorchis sinensis ; metacercaria ; Carassius carassius ; Pseudorasbora parva ; mucous substance ; chromatography

The seasonal variations of the rate and intensity of metacercarial infection of C. sinensis in P. parva were observed. The fish were collected at Sun-Am river which located in Kim-Hae City, Kyong-Sang-Nam Do(=Province), Korea, from March 1983 to February 1984 every month. A total of 788 fish was examined. The number of metacercariae in each fish was individually counted after the individual digestion by artificial gastric juice. The result was as follows: During one year, 513(65.1%) out of 788 fish were infected with metacercariae. In May, June, July and September, the infection rates ranged from 82. 0 % to 98. 6% whereas the rates was relatively low in March, April, November and February raning from 11. 4% to 64.7%. The intensity of infection was similar with those of infection rates. The mean intensity per infected fish was 103.0 and standard deviation was 118.9 throughout one year. The highest mean intenstiy was in June(294. 8) and the lowest in Novebmver(11.1). The observed frequency of fish with certain intensities of metcercariae were fitted to theoretical equations derived from negative binomial distribution in March, April, November and February(p>0.05). Meanwhile, the equation of lognormal distribution were fitted with the observed frequencies in May, June, July and September(p>0.05, p>0.75). The variance/mean ratio varied by month. The value was the highest in July(814.3) and the lowest in November(158.8). Unlike our hypothesis, the metacercarial density of Clonorchis sinensis in its the most favourable fish host, Pseudorasbora parva showed considerable seasonal variations in the hyperendemic area. The possible factors were discussed.
parasitology-helminth-trematoda ; Clonorchis sinensis ; epidemiology ; Pseudorasbora parva ; metacercaria ; negative binomial distribution ; intermediate host ; lognormal distribution

Cercariae of Clonorchis sinensis were attempted to penetrate into various fry of fresh water fishes in order to examine the conditions of infection and the further development in the fish. The following conclusions were made. Cercariae of C. sinensis penetrated into the muscle of the fry of Pseudorasbora parva were found to be able to develop. Cercariae penetrated into the fry of Pseudorasbora parva migrated into the organs of the fry to kill their host. From each dead individual of P. parva, more than 10 larvae of C. sinensis could be discovered. Cercariae attached on the Cyprinus carpio, Carassius and gold fish were almost killed before penetration into the body and even one or two cercariae penetrated were also killed as time passed. Cercariae of C. sinensis infected on the fry of Cyprinus Carpio, Carassius auratus and gold fish could not survive more than 60 days. Cercariae penetrated into Cyprinus carpio and Carassius auratus could not develop into complete metacercariae even after 3O days. Cercariae of Clonorchis sinensis penetrated into the fry of Aplocheilus latipes were killed within 10 hours and the cercariae attached on the caudal fin were destroyed in 2 hours. It was found that no cercariae of Clonorchis sinensis could penetrate into the body of the fry of Misgurnus anguillicaudatus.
parasitology-helminth-trematoda-Clonorchis sinensis ; cercariae ; Pseudorasbora parva ; Cyprinus carpio ; Carassius auratus ; gold fish ; Aplocheilus latipes ; Misgurnus anguillicaudatus ; mucous substance

In order to determine the infestation patterns for metacercaria of digenetic trematodes, several kinds of fresh-water and brackish-water fish were caught in River Hyungsan, Kyungpook Province, Korea and examined from March to October in 1983. They were collected by netting, fishig with rod and line, or using the bait of crushed oil cake in transparent plastic bowls, and were dissected into the flesh, scales and fins with tail, and then examined for the presence and infestation density of larval trematodes. Of the 11 kinds of fish examined, the encysted larvae of Exorchis oviformis were found all of them, Metagonimus yokogawai from 9 kinds, Cyathocotyle orientalis, Metacercaria hasegawai and Metorchis orientalis from 6 kinds, and Clonorchis sinensis from 4 kinds in the present study. In the intensity of infestation with Clonorchis sinensis, the Korean shiner, Gnathopogon atromaculatus Nichols et Pope, was the most heavily infected species, the average number of metacercariae per gram of fish flesh being 45.5, followed by the striped shiner, Puntungia herzi Herzenstein 11.6, and Southern top-mouthed minnow, Pseudorasbora parva (Temminck et Shlegel), 9.7. The intensity of infestation with the Metagonimus larvae in 8 species of fresh-water fish was relatively low, and the average number per gram of flesh varied from 0.23 to 9.1. In comparison, the brackish-water fish were more heavily infected and the mean number of cysts per gram of flesh in the sweetfish, Plecoglossus altivelis, was 32.9. The results of this study generally indicate that Clonorchis sinensis and Metagonimus yokogawai infection may occur by consuming raw fresh-water fish caught in the river Hyungsan, Kyungpook Province, Korea.
parasitology-helminth-trematoda ; epidemiolgy ; Metagonimus yokogawai ; Cyathocotyle orientalis ; Metacercaria hasegawai ; Metorchis orientalis ; Clonorchis sinensis ; Gnathopogon atromaculatus ; Puntungia herzi ; Pseudorasbora parva

From March 1973 to September 1974, fresh-water fishes were collected in rivers in Kyungpook Province, Korea, using three collecting technics; throwing a cast-net, fishing and using a glass bowl containing crushed oil-cake as a bait. Twenty-one species of the fish caught in the rivers in Kyungpook Province were examined for the presence of the metacercaria of Clonorchis sinensis. Of these, 10 speciec of the fish harbored the encysted larvae. The most frequently infected one was Pseudorasbora parva 92.3 per cent, followed by Pseudogobio esocinus 90.4 per cent, Sarcocheilichthys sinensis 87.7, Hemibarbus labeo 87.2, and Pungtungia herzi 60.8 per cent, in decreasing order. The less frequently infected were Erythroculter erythropterus 13.0, Acanthorhodeus taenianalis 7.7, Paracheilognathus rhombea 5.9 and Acheilognathus limbata 4.2 per cent. In the intensity of infection with the larvae, Pseudorasbora parva was most heavily infected and the mean number of metacercaria per ml of flesh was 51.4, Pungtungia herzi, Gnathopogon atromaculatus, Pseudogobio esocinus, Sarcocheilichthys sinensis and Homibarbus labeo were infected intermediately (Their mean number varied 10.3 to 19.5). Whereas, Paracheilognathus rhombea, Acheilognathus limbata and Acanthorbodeus taenianalis were infected with a few cysts.
parasitology-helminth-trematoda ; Clonorchis sinensis ; Pseudorasbora parva ; Pseudogobio esocinus ; Sarocheilichtyhs sinensis ; Hemibarbus labeo ; Pungtungia herzi ; Erythroculter erythropterus ; Acanthorhodeus taenianalis ; Paracheilognathus rhombea ; Acheilognathus limbata ; host ; metacercaria

In an attempt to clarify the epidemiological feature of distomiasis in Tongjin riverside area, the prevalence of distomiasis in the residents and infection rates of the metacercariae in fresh-water fishes were investigated at the upper, middle and lower reaches of the river from January to April 1984. The results obtained were summarized as follows: Out of a total of 931 fresh-water fishes which composed of 33 different species, 611 fishes (65.6 percent) of 31 species were found positive with digenetic trematode metacercariae of 16 different species, and there were some differences in infection rates of the metacercariae among the fishes in the3 parts of the river; 53.8 percent in upper, 80.7 percent in middle, and 61.0 percent in lower reaches, respectively. Infection rates of the metacercariae of Exorchis oviformis, Metagonimus yokogawai, Echinochasmus japonicus, Metorchis orientalis and Clonorchis sinensis in the fishes were 48 percent, 29 percent, 11 percent, 7.9 percent and 6.3 percent, respectively. The average number of the encysted larvae of Clonorchis found in fish body/gram showed 4.44 in Pseudorasbora parva, Gnathopogon coreanus (1.2), Microphysogobio yaluensis(0.76), Abbottina springeri(0.4), Acanthorhodeus asmussi (0.21) and Cultriculus eigenmanni (0.17), respectively. The average number of the metacercariae of Metagonimus found in fish body/gram disclosed 34.01 in Zacco platypus, Zacco temmincki (16.46), Carassius carassius (5.35), Moroco oxycephalus (1.54), Aphyocypris chinensis (1.5) and etc., respectively. Detection rates of the eggs of Clonorchis and Metagonimus among residents were 1.1 percent and 0.8 percent, respectively, out of a total 923 persons.
parasitology-helminth-trematoda ; epidemiology ; Exorchis oviformis ; Metagonimus yokogawai ; Echinochasmus japonicus ; Metorchis orientalis ; Clonorchis sinensis ; Pseudorasbora parva ; Gnathopogon coreanus ; Microphysogobio yaluensis ; Abbottina springeri ; Acanthorhodeus asmussi ; Cultriculus eigenmanni

The author reported in the previous pager on his observation of sudden death of Clonorchis sinensis cercaria before penetration into the body of fry such as Cyprinus carpio and Carassius auratus. And in these studies, the reason behind the fact was investigated and it was found that the mucous substances on the surface of a certain fishes have a strong wormicidal effect to the larva of C. sinensis. When cercariae of C. sinensis were immersed into the mucous substance of gold fish for three minutes 36 seconds to 4 minutes 20 seconds, into that of Aplocheilus latipes for 4 minutes 30 seconds to 5 minutes 20 seconds, into that of Cyprinus carpio for 5 minutes 15 seconds to 6 minutes l6 seconds, and into that of Carassius auratus for 5 minutes 20 seconds to 7 minutes 30 seconds, it was observed that they were all killed. No wormicidal effect against C. sinensis could be observed with the mucous substance obtained from Pseudorasbora parva, Misgurnus anguillicaudatus and Ophicephalus argus. No wormicidal effect against Metagonimus sp. cercaria is observed with the mucous substance obtained from Cyprinus carpio, Carassius auratus. The wormicidal effect of the mucous substances obtained from gold fish was destroyed when heated over 60 C. The movements of metacercaria of C. sinensis stopped after 10 minutes application of the mucous substance obtained from Cyprinus carpio and they were killed within 30 minutes. When the adult worms collected from the bile duct of experimentally infected rabbits for 20 to 60 days, were immersed into mucous substance from Cyprinus carpio, they were killed between 25 minutes and 35 minutes. No wormicidal effect could be observed with the mucous substance obtained from dead Cyprinus carpio, Carassius auratus, gold fish, when applied to the adult worms and larvae of C. sinensis.
parasitology-helmith-trematoda-Clonorchis sinensis, Metagonimus sp. ; Cyprinus carpio ; Carassius auratus ; Aplocheilus latipes ; Pseudorasbora parva ; Misgurnus anguillicaudatus ; Ophicephalus argus ; gold fish ; mucous substance