Metagonimus yokogawai (Katsurada, 1912) Katsurada, 1912 (Trematoda: Heterophyidae) is parasitic in the small intestine of mammals including man and birds in Far Eastern Russia, Korea, Japan, China, and Taiwan. In the present study, the metacercariae and adults of M. yokogawai were redescribed to designate a neotype of this fluke together with reviews of previous studies including study histories from the first discovery to now. We particularly, attempted to review the study histories and morphological descriptions of M. yokogawai for the species validity, and compared with the morphological characteristics and life cycles of the closely related species, Metagonimus takahashii and Metagonimus miyatai. Finally, we proposed a differential key for the 8 known Metagonimus species distributed in East Asia. Metacercariae were obtained from the body muscles of sweetfish (Plecoglossus altivelis) collected in the Asahi River at Takebe-cho, Kita-ku, Okayama City, Okayama Prefecture, Japan. Adults were recovered from the small intestine of Syrian golden hamsters, to which the metacercariae had been fed 14 days before. A neotype was selected out of the present adult specimens. The Asahi River at Takebo-cho became the type locality of M. yokogawai. In conclusion, the present review shows that M. yokogawai, M. takahashii, and M. miyatai are valid and discriminated by means of morphological characteristics.
Animals ; Fish Diseases/parasitology ; Helminthiasis ; Heterophyidae/*anatomy & histology/*classification/isolation & purification ; Intestinal Diseases, Parasitic/veterinary ; Japan ; *Life Cycle Stages ; Mesocricetus/parasitology ; Microscopy ; Osmeriformes/parasitology ; Rodent Diseases/parasitology

OBJECTIVETo compare the efficacy of three different tissue stains, namely haematoxylin and eosin (H&E), periodic-acid Schiff (PAS) and immunohistochemical (IHC) stains for detection of Entamoeba histolytica (E. histolytica) trophozoites in abscessed liver tissues of hamster.

METHODSAmoebic liver abscess was experimentally induced in a hamster by injecting 1 × 10(6) of axenically cultured virulent E. histolytica trophozoites (HM1-IMSS strain) into the portal vein. After a week post-inoculation, the hamster was sacrificed and the liver tissue sections were stained with H&E, PAS and IHC stains to detect the amoebic trophozoite.

RESULTSThe three stains revealed tissue necrosis and amoebic trophozoites, but with varying clarity. H&E and PAS stained the trophozoites pink and magenta, respectively, however it was difficult to differentiate the stained trophozoites from the macrophages because of their similarity in size and morphology. On the other hand, IHC stain revealed distinct brown appearance of the trophozoites in the infected liver tissues.

CONCLUSIONSIt can be concluded that out of the three stains, IHC is the best for identification of E. histolytica trophozoites in tissue sections.

Animals ; Disease Models, Animal ; Entamoeba histolytica ; cytology ; isolation & purification ; Histocytochemistry ; methods ; Immunohistochemistry ; methods ; Liver Abscess, Amebic ; diagnosis ; pathology ; Male ; Mesocricetus ; Microscopy ; Parasitology ; methods ; Staining and Labeling ; methods ; Trophozoites ; cytology

Chronic Opisthorchis viverrini-induced hepatobiliary disease is associated with significant leukocyte infiltration, including activated macrophages; however, the polarization of infiltrating macrophages remains to be fully characterized. In this study, we characterized macrophage polarization and phenotype in chronic O. viverrini-induced hepatobiliary disease in humans and hamsters using gene expression and histochemical analysis. Chronic O. viverrini infection and associated hepatobiliary diseases were associated with iron loaded M2-like macrophages in both humans and hamsters. This study provides suggestive evidence that iron loaded M2-like macrophages promote hepatobiliary disease in chronic O. viverrini infection.
Animals ; Cricetinae ; Gene Expression Profiling ; Histocytochemistry ; Humans ; Immunohistochemistry ; Iron/*metabolism ; Liver Cirrhosis/*parasitology/*pathology ; Macrophages/*immunology/metabolism ; Mesocricetus ; Opisthorchiasis/*complications/*pathology ; Opisthorchis/*isolation & purification

Opisthorchis viverrini infection causes inflammation and liver injury leading to periductal fibrosis. Little is known about the pathological alterations in bile canaliculi in opisthorchiasis. This study aimed to investigate bile canalicular alterations in O. viverrini-infected hamsters and to examine the chemopreventive effects of curcumin on such changes. Hamsters were infected with O. viverrini and one group of animals was fed with 1% dietary curcumin supplement. Animals were examined during the acute infection phase, days 21 and 30 post-infection (PI) and chronic infection phase (day 90 PI). Scanning electron microscopy revealed that in the infected group fed with a normal diet, bile canaliculi became slightly tortuous by 30 day PI and more tortuous at day 90 PI. Transmission electron microscopy showed a reduction in microvilli density of canaliculi starting at day 30 PI, with a marked loss of microvilli at day 90 PI. These ultrastructral changes were slightly seen at day 21 PI, which was similar to that found in infected animals fed with 1% curcumin-supplemented diet. Notably, curcumin treatment prevented the reduction of microvilli density, reduced the dilation of bile canaliculi, and decreased the tortuosity of the bile canaliculi relative to non-infected animals on a normal diet at days 30 and 90 PI. These results suggest that curcumin reduces alteration of bile canaliculi and may be a promising agent to prevent the onset of bile duct abnormalities induced by O. viverrini infection.
Animals ; Anthelmintics/*administration & dosage ; Bile Canaliculi/*pathology/ultrastructure ; Chemoprevention/methods ; Cricetinae ; Curcumin/*administration & dosage ; Disease Models, Animal ; Electrons ; Liver/pathology/ultrastructure ; Male ; Mesocricetus ; Microscopy, Electron, Scanning ; Microscopy, Electron, Transmission ; Opisthorchiasis/parasitology/*pathology/*prevention & control ; Opisthorchis/*growth & development

We investigated the induction of resistance to Clonorchis sinensis infection by prior infection in rat and hamster models. Animals were challenged with C. sinensis metacercariae, then treated with praziquantel and reinfected. Worm recovery rate in reinfected animals was used to estimate resistance to reinfection. The determined resistance rates to reinfection in rats and hamsters were 97.7% and 10.3%, respectively. In rats, cure from the primary infection of C. sinensis increased resistant to reinfection, and the greatert the worm burden and the longer the duration of primary infection, the higher was the resistance rate. For primary infection doses of 10, 40 and 100 metacercariae per rat, the resistance rates were 87.4%, 93.8% and 98.4%, respectively. The resistance rates in rats after 2 or 8-week primary infection were 78.7% and 95.3%, respectively. All worms recovered from reinfected rats were immature. When cured rats were administered with methylprednisolone, resistance to reinfection became impaired. These findings indicate that rats develop a high degree of resistance to reinfection by C. sinensis after cure. The growths and maturations of reinfected worms were also impaired.
Animals ; Anthelmintics/administration & dosage/therapeutic use ; Anti-Inflammatory Agents/administration & dosage ; Clonorchiasis/*immunology/parasitology/*pathology ; Clonorchis sinensis/*pathogenicity ; Disease Models, Animal ; Female ; Hamsters ; Immunocompetence ; Immunosuppression ; Male ; Mesocricetus ; Methylprednisolone/administration & dosage ; Praziquantel/administration & dosage/therapeutic use ; Rats ; Rats, Sprague-Dawley ; Support, Non-U.S. Gov't