The question of infectivity and prevalence of Clonorchis sinensis in Cheju province (Quelpart Island) was arisen to authors since the several surveys on the endemic diseases were performed in this island. Therefore, authors decided to solute this question. Then the survey on the possible second intermediate host of Clonorchis sinensis was performed and reported already with negative finding. At present time, authors carried out the collection of all kinds of fresh-water snails through all areas of this island, to confirm the presence or not of Parafossarulus manchouricus, the only first intermediate host of Clonorchis sinensis in Korea . And the following results were obtained. The fresh-water snails collected in the survey were Semisulcospira libertina Gould and Lymnaea ollula Gould. Parafossarulus manchouricus Bourguigant was not collected in this island. It is confirmed that the Clonorchis sinensis can not be prevalent in this island.
parasitology-helminth-trematoda-Clonorchis sinensis ; life cycle ; epidemology ; Parafossarulus manchouricus ; Semisulcospira libertina Gould ; Lymnaea ollula Gould

The present study was performed to observe tegumental ultrastructure of Echinoparyphium recurvatum according to developmental stages. Worms (1, 3, 5 and 15-day old) were recovered from chicks experimentally infected with metacercariae from Radix auricularia coreana. One-day old worms were elongated and ventrally concave, and covered with peg-like tegumental spines except the adjecent areas of the head crown and excretory pore. Type I sensory papillae were distributed on the lip of the oral sucker, and grouped ciliated papillae were around the oral sucker. Peg-like tegumental spines were densely distributed on the anterior surface of the ventral sucker level. The ventral sucker had an aspinous tegument and no sensory papillae. Tegumental spines on the posterior surface of the ventral sucker level were sparsely distributed and disappeared posteriorly. In 3 and 5-day old worms, the tegument around the oral sucker was aspinose and wrinkled concentrically. The ventral sucker had a wrinkled tegument and many bulbous papillae. Type I sensory papillae were distributed between the bulbous papillae. Tegumental spines were spade-shaped with a terminal tip. A total of 45 collar spines including 4 end group ones on both ventral corners was alternately arranged in 2 rows. The 15-day old worms were very stout and their tegumental spines were tongue-shaped without a terminal tip. From the above results, it is confirmed that the surface ultrastructure of E. recurvatum was generally similar to that of other echinostomatid flukes. However, some features, i.e., morphological change of tegumental spines and appearence of sensory papillae on the ventral sucker according to development, and number, shape and arrangement of collar spines, were characteristic, which may be of taxonomic and bioecological significance.
Animals ; Chickens ; Echinostomatidae/anatomy & histology/growth & development/*ultrastructure ; Life Cycle Stages ; Lymnaea/parasitology ; Microscopy, Electron, Scanning

Three freshwater snail species of the family Lymnaeidae have been reported from Korea, Radix auricularia coreana, Austropeplea ollula and Fossaria truncatula. Out of 3 lymnaeid snail species, A. ollula was naturally infected with the Echinostoma cinetorchis cercariae (infection rate = 0.7%). In the experiments with the laboratory-bred snails, F. truncatula as well as A. ollula was also susceptible to the E. cinetorchis miracidia with infection rates of 25% and 40%, respectively. All of three lymnaeid snail species exposed to the E. cinetorchis cercariae were infected with the E. cinetorchis metacercariae. It is evident that A. ollula acts as the first molluscan intermediate host of E. cinetorchis in Korea, and F. truncatula may be a possible candidate for the first intermediate host of this intestinal fluke. Also, three lymnaeid snail species targeted were experimentally infected with E. cinetorchis metacercariae.
Animals ; Echinostoma/pathogenicity/*physiology ; Echinostomiasis/parasitology ; Host-Parasite Relations ; Korea ; Lymnaea/*parasitology ; Rats ; Rats, Sprague-Dawley ; Support, Non-U.S. Gov't

Freshwater snails of the family Lymnaeidae play an important role in the transmission of fascioliasis worldwide. In Vietnam, 2 common lymnaeid species, Lymnaea swinhoei and Lymnaea viridis, can be recognized on the basis of morphology, and a third species, Lymnaea sp., is known to exist. Recent studies have raised controversy about their role in transmission of Fasciola spp. because of confusion in identification of the snail hosts. The aim of this study is, therefore, to clarify the identities of lymnaeid snails in Vietnam by a combination of morphological and molecular approaches. The molecular analyses using the second internal transcribed spacer (ITS2) of the nuclear ribosomal DNA clearly showed that lymnaeids in Vietnam include 3 species, Austropeplea viridis (morphologically identified as L. viridis), Radix auricularia (morphologically identified as L. swinhoei) and Radix rubiginosa (morphologically identified as Lymnaea sp.). R. rubiginosa is a new record for Vietnam. Among them, only A. viridis was found to be infected with Fasciola spp. These results provide a new insight into lymnaeid snails in Vietnam. Identification of lymnaeid snails in Vietnam and their role in the liver fluke transmission should be further investigated.
Animals ; Cluster Analysis ; DNA, Ribosomal Spacer/chemistry/genetics ; Fasciola/*isolation & purification ; Lymnaea/*anatomy & histology/genetics/*parasitology ; Molecular Sequence Data ; Phylogeny ; Sequence Analysis, DNA ; Sequence Homology, Nucleic Acid ; Vietnam