Tegumental ultrastructures of Echinochasmus japonicus were observed by scanning electron microscopy. The worms were recovered from albino rats which were experimentally infected with the metacercariae obtained from Pseudorasbora parva. Followings are summarized findings. The worms were minute and plumpy gourd-shaped with attenuated anterior and round posterior end. The tegument of whole body was wrinkled transversely and covered with cobblestone-like cytoplasmic processes. Head crown was armed with 24 collar spines which were embedded in cytoplasmic pockets. The spines were arranged in a row with an interruption at dorsomedian line, however, the 2nd and the 4th spines were outstretched more than others. Oral and ventral suckers were muscular with numerous type II sensory papillae, and genital pore opened between the two suckers. Tegumental spines were spade-shaped with broad base and pointed tip. They were compact in ventro-lateral tegument or dorsal surface of anterior body. The were not found between the two suckers and dorsal surface of posterior body. Two types of sensory papillae, uni-ciliated (Type I) and roundly swollen sensory papillae (Type II), were observed. The type I papillae were chiefly distributed on ventral surface of tegument and type II were on the lips of suckers. Arrangement of collar spines, shape and distribution of tegumental spines or sensory papillae are regarded as characteristic features of E. japonicus.
parasitology-helminth-trematoda ; Echinochasmus japonicus ; electronmicroscopy

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

Four cases of human infection by Echinochasmus japonicus (Trematoda; Echinostomatidae) were proven by the recovery of adult worms after a treatment with praziquantel (10 mg/kg in single dose) and purgation in February 1984 in Korea. The patients were 3 middle-aged men and 1 elderly woman residing in a riverside village of Kangjin-gun ( Tamjin river), Jeonranam-do, an ever-known endemic area of metagonimiasis. The treatment revealed numerous M. yokogawai worms together with 1-43 (total 54 ) specimens of E. japonicus and/or a few number of other kinds of trematodes or cestodes. The patients had gastrointestinal troubles such as indigestion and abdominal discomfort, probably due to these fluke infections. They have been eating some raw flesh of fresh water fishes such as cyprinoid ones or sweetfish caught from the river. This is the first record of human E. japonicus infection in the literature.
parasitology-helminth-trematoda ; case report ; Echinochasmus japonicus ; Metagonimus yokogawai

During February 1982 to Septemner 1983, a total of 105 domestic ducks (Anas platyrhynchos var. domestica Linnaeus) were collected from Ichon Gun, Puasn City, Chunchon City, Yanggu Gun, Taejeon City and unknown areas in Korea. In the results, six trematode and one nematode species of helminth parasites were obtained and described as follows: Amphimerus anatis Yamaguti, 1933, Echinostoma miyagawai Ishii, 1932, Echinochasmus japonicus Tanabe, 1926, Cryptocotyle sp., Notocotylus attenuatus (Rudolphi, 1809) Kossack, 1911, Apatemon sp, and nematode species, Heterakis gallinarum Schrank, 1788. From this collection, Amphimerus anatis Yamaguti, 1933, Echinochasmus japonicus Tanabe, 1926, Genus Cryptocotyle Luhe, 1899 and genus Apatemon Szidat, 1928 were firtstly recorded in Korea.
parasitology-helminth-trematoda ; duck ; Anas platyrhyncos var. domestica ; epidemiology ; Amphimerus anatis Echinostoma miyagawai ; Echinochasmus japonicus ; Cryptocotyle sp. ; Notocotylus attenuatus ; Heterakis gallinarum ; Amphimerus anatis

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

In order to clarify infestation pattern for the encysted larvae of digenetic trematodes from fresh-water fishes, this survey was carried out from March to September, 1983. A total of 380 fishes of 32 species were collected with netting at the three reaches, upper, middle and lower in Mangyeong riverside area. After the fishes were dissected into small scraps, they were pressed under cover glass and examined for the presence of those of digenetic trematodes with a microscope. The results obtained were as follows: Out of a total of 380 fishes inspected, 320 fishes (84 percent) from 31 species were found positive with digenetic trematode metacercariae; more than 10 species of the metacercariae were detected in Pseudorasbora parva; Gnathopogon majimae, Microphysogobio yaluensis, Cultriculus eigenmanni and Gnathopogon coreanus (more than 8 species); Aphyocypris chinensis(8 species) and etc. respectively. Clonorchis sinensis metacercariae were found positive from 93 fishes (25 percent) from 12 species detection rates in other species of digenetic trematode metacercariae from various fishes were; Exorchis oviformis, 261 fishes (57 percent) from 28 species; Cyathocotyle orientalis, 47 fishes (12 percent) from 12 species; Metorchis orientalis, 21 fishes (6 percent) from 12 species; Metagonimus yokogawai, 164 fishes (43 percent) from 26 species; Pseudexorchis major, 71 fishes (19 percent) from 18 species; Metacercaria hasegawai, 77 fishes (20 percent) from 25 species; Centrocestus armatus, 24 fishes (6 percent) from 7 species; Echinochasmus japonicus, 2 fishes (0.5 percent) from 2 species, and unidentified species, 34 fishes (9 percent) from 15 species respectively. The sums of average number of the encysted larvae of all species found in fish body/gram showed 83 in P. parva, Cobitis taenia (74.2), A. chinensis (28.5), Pseudoperilampus uyekii (26.6), G. majimae (19.6) and etc. respectively and the average peak number of each metacercaria in fish body/gram showed 21.7 C. sinensis, 24 E. oviformis , 15.3 M. orientalis and 6.1 E. japonicus in P. parva ; 42.7 C. orientalis and 25.1 M. yokogawai in C. taenia; 8.3 C. armatus and 8.3 M. hasegawai in P. uyekii; 6.3 P. major in Carassius carassius, and 2.9 unidentified species in G. majimae respectively.
parasitology-helminth-trematoda ; Clonorchis sinensis ; epidemiology ; Pseudorasbora parva ; Gnathopogon majimae ; Microphysogobio yaluensis ; Cultriculus eigenmanni ; Gnathopogon coreanus ; Aphyocypris chinensis ; Cyathocotyle orientalis ; Metorchis orientalis ; Exorchis oviformis ; Metagonimus yokogawai ; Pseudexorchis major ; Metacercaria hasegawai ; Centrocestus armatus ; Echinochasmus japonicus

In an attempt to clarify the epidemiological feature of C. sinensis in Mangyeong riverside area, the prevalence of clonorchiasis, infestation rate of the cercariae in Parafossarulus manchouricus, and detection rate of the metacercariae in fresh-water fishes were investigated from March 1 to September 30, 1983 at the upper, middle and lower reaches of the river. The results obtained were summarized as follows:Detection rate of C. sinensis egg among inhabitants was 8.2 percent out of a total of 1,266 persons. but the differences in detection rates were not statistically signifcant among upper, middle and 1ower reaches. According to sex, the detection rates were 10.3 percent in male and 6.1 percent in female (p<0.05), but by age groups, increases of the rates were observed as increase in age (p<0.05). Out of a total of 380 fresh-water fishes of 32 different species, 93 fishes (25 percent) of 12 species were found positive with Clonorchis metacercariae, and there were differences in infection rates of the metacercariae among the fishes in 3 parts of the river; 11 percent in upper, 35 percent in middle, and 34 percent in lower reaches respectively. The metacercarial detection rates from various fishes were 97 percent in Pseudorasbora parva, Cultriculus eigenmanni (85 percent), Gnathopogon strigatus (67 percent), Microphysogobio yaluensis (50 percent), Gnathopogon coreanus (47 percent), Pungtungia herzi(44 percent), Abbottina rivularis (40 percent), Moroco oxycephalus (33 percent), Coreoleuciscus splendidus (32 percent), Gnathopogon majimae (26 percent), Rhodeus ocellatus (7 percent), and Aphyocypris chinensis (3 percent) respectively. Although very few P. manchouricus were collected at upper reach, 12 snails (0.7 percent) among a total of 1,713 were found infected with Clonorchis cercariae. Also the cercariae of Echinochasmus japonicus (7.99 percent), Lexogenes liberum (0.99 percent), Cyathocotyle orientalis (0.75 percent), Exorchis oviformis (0.23 percent) and Asymphylodora japonica (0.05 percent) were detected from the snails.
parasitology-helminth-trematoda ; Clonorchis sinensis ; clonorchiasis ; epidemiology ; Pseudorasbora parva ; Cultriculus eigenmanni ; Gnathopogon strigatus ; Microphysogobio yaluensis ; Gnathopogon coreanus ; Pungtungia herzi ; Abbottina rivularis ; Moroco oxycephalus ; Coreoleuciscus splendidus ; Gnathopogon majimae ; Rhodeus ocellatus ; Aphyocypris chinensis ; Parafossarulus manchouricus ; Echinochasmus japonicus ; Lexogenes liberum ; Cyathocotyle orientalis ; Exorchis oviformis ; Asymphylodora japonica