• Parasites, Hosts and Diseases
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• v.54 no.4
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• pp.477-484
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• 2016

There is renewed interest in natural products as a starting point for discovery of drugs for schistosomiasis. Recent studies have shown that phytol reveals interesting in vivo and in vitro antischistosomal properties against Schistosoma mansoni adult worms. Here, we report the in vitro antischistosomal activity of phytol against Schistosoma haematobium juvenile and adult worms and alterations on the tegumental surface of the worms by means of scanning electron microscopy. The assay, which was carried out with 6 concentrations (25, 50, 75, 100, 125, and $150{\mu}g/ml$) of phytol, has shown a promising activity in a dose and time-dependent manner. There was a significant decline in the motility of the worms and a mortality rate of 100% was found at 48 hr after they had been exposed to phytol in the concentration of $150{\mu}g/ml$. Male worms were more susceptible. On the ultrastructural level, phytol also induced tegumental peeling, disintegration of tubercles and spines in addition to morphological disfiguring of the oral and ventral suckers. This report provides the first evidence that phytol is able to kill S. haematobium of different ages, and emphasizes that it is a promising natural product that could be used for development of a new schistosomicidal agent.

• 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.1-10
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• 1984

This study was performed to observe the chronological changes in the tegumental structure of M. yokogawai using scanning electron microscope. The subjected worms were encysted metacercariae obtained from the sweetish, and 2-day, 1-week and 4-week old worms experimentally reared in albino rats. The results are as follows: 1. The tegument of encysted metacercariae showed many transverse shallow rugae, which were more remarkable in posterior half body, i.e., posterior to ventral sucker. The whole surface was armed with many scale-like spines; 7~8 pointed ones on anterior body and 2~3 pointed on posterior body. The ciliated knob-like papillae (Type I) were abundant around oral and ventral suckers, which grouped 2, 3 or 4 in number in most cases. A few round swellings of tegument(Type lI were observed only on oral sucker. 2. The tegumental surface of 2-day old worms showed deeper rugae, and the anterior half covered with knob-like processes of distal cytoplasm and the posterior half with cobblestone-like ones. Interspinous space became more wide and 9 pointed spines appeared on anterior dorsal surface. The sensory papillae enlarged but not changed in their distribution. 3. The tegument of 1-week old worms revealed knob-like cytoplasmic processes in posterior half body and velvety ones around oral sucker. The scale-like spines of anterior half body changed remarkably to the slender ones of posterior body at the level of ventral sucker. In dorsal surface, the arrangement of the Type I papillae were bilaterally symmetrical. 4. The tegument of 4-week old worms were finely differentiated and the posterior tegument covered with velvety cytoplasmic processes. The spines had remarkably grown in length and width but the density remained nearly unchanged. The papillae also became larger but their morphology and distribution were not different from younger worms. However, the round elevation of cytoplasmic ridges (Type III papilla) appeared bilaterally on inner wall of oral sucker, approximately 8 in number. From the above results, it is considered that the tegument of juvenile iH. yokogawai continued to differentiate until 4 weeks after infection.

• Parasites, Hosts and Diseases
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• v.57 no.6
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• pp.657-664
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• 2019

We identified the echinostome metacercariae in Chinese mystery snails, Cipangopaludina chinensis malleata, from Xiengkhuang Province, Lao PDR with morphologies of adult worms recovered. Total 20 snails were examined with artificial digestion method and then the collected metacercariae were orally infected to a mouse and a rat. Adult worms recovered from experimental animals were observed with a light microscope and a SEM. The metacercariae were round, 125×123 ㎛ in average size, with a moderately thick cyst wall, collar spines distributed in the head collar and excretory granules in 2 canals of excretory tube. Adult flukes (3-week-old in a rat) were elongated, ventrally curved and 5.310×1.023 mm in average size. Head collar distinct, bearing 43 collar spines with 5 end group ones on each side. Oral sucker subterminal, prepharynx very short, pharynx well developed, and esophagus relatively short. Cirrus sac well developed, with a saccular seminal vesicle, and ventral sucker very large. Ovary round and on the median line of the body. Testes tandom and elongated. Eggs operculated, elliptical and 90×57 ㎛ in average size. In the SEM observation, the head crown prominent, with 43 collar spines resembled with horns of younger stag. Scale-like tegumental spines were densely distributed on the surface between the head collar and ventral sucker, and their densities were decreased posteriorly. Conclusively, the metacercariae detected in C. chinensis malleata from Lao PDR were identified as those of Echinostoma macrorchis based on the morphological characteristics of adult worms.

• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.111-122
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• 1985

The present study was performed to observe the ultrastructure of the integument of adult Paragonimus westermani. Dogs experimentally infected with 60 metacercariae of F. westermani were autopsied 4 months after the infection. Adult p. westermani were extracted from the dogs and the fine structure was studied by means of scanning and transmission electron microscope. The findings are as follows: 1. Scanning electron microscopic findings showed that the spines and the papillae are distributed at whole body surface but the well developed spines or papaillae are shown around the oral sucker and ventral sucker. 2. At the end of the body, excretory pore was found, the shape was irregular. 3. Transmission electron microscopic findings showed that plasma membrane, tegument, basal lamina, connective tissue, circular muscle layer, longitudinal muscle layer. nerve axon and tegumental cell were observed. 4. In higher magnification, plasma membrance and bar-shaped granules were found at the outer surface of the tegument.

• Parasites, Hosts and Diseases
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• v.50 no.2
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• pp.177-180
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• 2012

Cercaria caribbea LVIII Cable, 1963 (Digenea: Cyathocotylidae) was detected from a brackish water gastropod species (Cerithideopsilla cingulata) in a coatal area of Shinan-gun, Jeollanam-do (Province), the Republic of Korea, and its surface ultrastructure was studied using a scanning electron microscope. The cercariae were found freely swimming or enveloped within daughter sporocysts when the snail host was mechanically broken. They were morphologically characterized by a linguiform and ventrally concave body, a long and bifurcated tail, and the presence of a holdfast (=tribocytic) organ posterior to the ventral sucker. On the whole ventral and dorsal surfaces, peg-like tegumental spines were densely distributed. Around the oral sucker, several sensory papillae, each with a short cilium, were distributed, and on the tail, sensory papillae, each with an extensively long cilium, were observed. This is the first record describing a cyathocotylid cercaria from a brackish water gastropod in the Republic of Korea.

• Parasites, Hosts and Diseases
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• v.61 no.3
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• pp.298-303
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• 2023

This study aimed to describe a rare case of gnathostomiasis in the vocal cord. A 54-yearold Chinese woman living in Korea visited with a chief complaint of voice change at the outpatient department of otorhinolaryngology in Hallym Sacred Heart Hospital, Hallym University on August 2, 2021. She had eaten raw conger a few weeks before the voice change developed, but her medical history and physical examinations demonstrated neither gastrointestinal symptoms nor other health problems. A round and red cystic lesion, recognized in the anterior part of the right vocal cord, was removed using forceps and scissors through laryngeal microsurgery. The histopathological specimen of the cyst revealed 3 cross-sections of a nematode larva in the lumen of the cyst wall composed of inflammatory cells and fibrotic tissues. They differ in diameter, from 190 ㎛ to 235 ㎛. They showed characteristic cuticular layers with tegumental spines, somatic muscle layers, and gastrointestinal tracts such as the esophagus and intestine. Notably, intestinal sections consisted of 27-28 lining cells containing 0-4 nuclei per cell. We tentatively identified the nematode larva recovered from the vocal cord cystic lesion as the thirdstage larva of Gnathostoma, probably G. nipponicum or G. hispidum, based on the sectional morphologies.

• Parasites, Hosts and Diseases
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• v.32 no.3
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• pp.143-148
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• 1994

The metacercanae of the genus Stictodora encysted in gobies, Acnnthogobiln Snuimanw, purchased from a local market of Haenarn-gun, Chollanam-do, were identified as those of S. fuscotum A total of 1,437 metacercariae were collected from 30 gobies and sonle of them were orally fed to cats in order to obtain the adult worms. The metacercariae were 0.194-0.301 mm by 0.168-0.270 mm In size, yellowish brown, round to elliptical, and with a thin and transparent cyst wall. The excysted larvae were 0.280-0.423 mm long and 0.150-0.184 mm wide, beset with numerous tegumental spines on the anterior half of the body, and equipped 10 a characteristic ventrogenital sac. Total 21 adult worms were recovered from 2 cats 7 days after infection. The adult worms were small, leaf-like, 0.514-0.918 mm long and 0.235-0.377 mm wide. The ventrogenital sac was elliptical and its gonotyl was armed with 13-18 spines which were radially arranged and appeared as fan-shape. It has been confirmed that A. flavimanus is a second interinedlate host of 5. Juscatum In Korea.

• Parasites, Hosts and Diseases
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• v.36 no.2
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• pp.81-90
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• 1998

The present study was performed to observe the infection status of several kind of animals with indigenous Gnnthostomn in Korea, and morphological characteristics of gnathostome larvae detected from pit-viper, Askistronon breuiccudus, for the species bullfrogs. several kinds of snakes, j.e., 55 Elnphe rufodorsata, 2 Dinodon rufozonatum rufzonatum. 62 Rhnbdophis tisrinus tigrinus and 87 Askistronon app., and 438 cats were examined. A total of 21 larval gnathostomes was detected from 12 pit-vipers, A. breuicnudus. They were 2.233 x 0.343 mm in average size and covered with about 210 transverse rows of minute cuticular spines. Their characteristic head bulbs were provided with 4 rows of hooklets of which average numbers in each row were 36.8, 39.0, 41.7 and 44.3. posteriorly. In the cross sections of midgut level, the intestinal wall consisted of a single layer of 19-25 elongate epithelial cells with a single nucleus. SEM observation of the larvae revealed unique features of head bulb , cuticular spines on transverse striations and a cervical papilla. On the basis of above morphological characteristics, they were identified as the advanced third-stage larvae of Gnothostomo hispinum. It was first confirmed that the pit-viper. ABkistronon breuicaunus is the snake intermediate host of G. hispidun.

• Parasites, Hosts and Diseases
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• v.54 no.4
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• pp.537-541
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• 2016

Stellantchasmus falcatus (Digenea: Heterophyidae) is first reported from Cambodia through recovery of the metacercariae from mullet fish and adult flukes from an experimentally infected hamster. We purchased 7 mullets, Chelon macrolepis, in a local market of Phnom Penh, Cambodia, and each of them was examined by the artificial digestion method on May 2010. The metacercariae of S. falcatus were detected in all mullets (100%) examined, and their average density was 177 per fish. They were elliptical, $220{\times}168{\mu}m$ in average size. They were orally infected to an hamster to obtain adult flukes. Adults recovered at day 10 post infection were observed with a light microscope and a scanning electron microscope (SEM). They were small, $450{\times}237{\mu}m$ in average size, had a small oral sucker ($41{\times}50{\mu}m$), subglobular pharynx ($29{\times}21{\mu}m$), slender esophagus ($57{\mu}m$), long and thick-walled expulsor ($119{\times}32{\mu}m$), spherical ovary ($58{\times}69{\mu}m$), and 2 ovoid testes (right: $117{\times}74{\mu}m$; left: $114{\times}63{\mu}m$). Eggs were small, yellow, and $23{\times}12{\mu}m$ in average size. In SEM observations, tegumental spines were densely distributed on the whole tegument, and single small type I sensory papillae were distributed around the lip of oral sucker. The small ventral sucker was dextrally located and had 8 type I sensory papillae on the left margin. It has been first confirmed in the present study that the mullet, C. macrolepis, is playing the role of a second intermediate host of S. falcatus in Cambodia.