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, Cultriculus eigenmanni, in the field, 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 brief summary of the leading facts gained through the experiments. All the ten fish (mean body weight 13.4 +/- 3.43 g) which were caught in Ok-ku irrigation reservoir were infected with the metacercariae and the average number of the metacercariae found in the fish body/gram was 4.55. The fish was easily subject to invasion of the cercaria, and the examination of the cercariae after having the fish infected disclosed that 24 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. In the case of control fish, Pseudorasbora parva, both penetrating ability of the cercariae and the infective degree of the metacercariae to control host were stronger as compared with the fish host because that the control fish had higher suceptibility to C. sinensis. 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 fish 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 percent). Percentage of orally administered metacercariae developing to maturity in rabbit is 10.46 percent in the last case. 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. parva, suitable as the second intermediate host in addition to our previous observation results.
parasitology-helminth-trematoda ; Clonorchis sinensis ; epidemiology ; Cultriculus eigenmanni ; metacercaria ; intermediate host

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

In order to know relationship between the clavate cells of epidermis and infectivity of metacercariae of C. sinensis. histological investigation of epidermis was carried out on the 26 species of fresh-water fish collected from the main rivers in Korea. Results were summarized as it follows: In general clavate cell had a single nucleus at its center. However it was observed in Liobagrus mediadiposalis and Pelteobagrus fuluidraco that clavate cell had two nuclei with and independent so-called light halo of Oxner and in some cases had none of them. In following species; Misgurnus anguillicaudatus, Cobitis taenia, Liobagrus mediadiposalis, Pelteobagrus fuluidraco, Parasilurus asotus and Anguilla japonica, scales were not detected or buried in the dermis layer, and the epidermis was mostly consisted of clavate cells. Among these species, it was observed that no metacercariae were found. In case of Cyprinus carpio, Carassius carassius (crusian carp and golden crusian carp), Sarcocheilichthys czerskii, Pungtungia herzi and Coreoleuciscus splendius, scales were exposed over the epidermis, in which clavate cells were abundantly found. In these species, a few of the metacercariae were detected. On the other hand, no clavate cells were observed in Pseudorasbora parva , Zacco platypus, Microphysogobio koreensis, Gnathopogon majimae, Gnathopogon coreanus, Acheilognathus signifer, Acheilognathus yamatsutae, Cultriculus eigenmanni, Coreoperca herzi, Pseudoperilampus uyekii, Pseudoperilampus notatus and Pseudogobio esocinus. These fishes with exposed scales on the epidermis were well known to serve as the second intermediate hosts of C. sinensis. From the above results obtained, it was suggested that the existance of clavate cells in the epidermis of the fresh-water fish seems to be correlated with the infectivity of the metacercariae of C. sinensis.
parasitology-helminth-trematoda-Clonorchis sinensis ; host ; Liobagrus mediadiposalis ; Pelteobagrus fuluidraco ; Misgurnus anguillicaudatus ; Cobitis taenia ; Liobagrus mediadiposalis ; Pelteobagrus fuluidraco ; Parasilurus asotus ; Anguilla japonica ; Cyprinus carpio ; Carassius carassius ; Sarcocheilichthys czerskii ; Pungtungia herzi ; Coreoleuciscus splendius ; Pseudorasbora parva ; Zacco platypus ; Microphysogobio koreensis ; Gnathopogon majimae ; Gnathopogon coreanus ; Acheilognathus signifer ; Acheilognathus yamatsutae, Cultriculus eigenmanni ; Coreoperca herzi ; Pseudoperilampus uyekii ; Pseudoperilampus notatus ; Pseudogobio esocinu