In order to confirm whether the migrating larvae of parasites could carry pathogenic organisms into liver and cause hepatitis, a series of experiments has been carried out. Clonorchis sinensis: Recovery rate of larvae in the abdominal cavity of rabbits: One to seven days after the administration adolescariae were recovered from the abdominal cavity in less than l percent of the total number of metacercariae given. Generally, 1-6 larvae were found from each animal which was given 900-1,000 metacercariae, though many larvae were already found in the common bile ducts or remained still in intestine. Fate of Clonorchis sinensis in abdominal cavity: The young or mature worms which were introduced directly into the abdominal cavity were examined l5, 32, 40 and 42 days after the inoculation. Several larvae were found on the surface of liver in four animals. All the worms on the surface of the liver were dead and the biopsied liver tissues on the area where the worms were attached showed no pathological changes. Two of them were between bile duct and liver tissue but pus cell infiltration surrounding them was observed. In every case, pus cell infiltration was found in the peripheral portion of the liver and pus nodules on the surface of intestine and mesentery. The nodule in the intestinal wall contained the eggs of Clonorchis sinensis. Two worms in the abdominal cavity were still alive. From the above results it is suggested that the larvae of Clonorchis sinensis were capable of penetrating the intestinal wall and reaching the organs in the abdominal cavity and surviving for l5-42 days, but they were unable to penetrate the organs. No bacterial flora appeared from the lesion by culture method. Fate of Clonorchis sinensis which was inoculated into the peripheral region of liver: Small abscess was observed at the same area. Microscopically, the area became edematous and the vessels in the peripheral region were dilated. The parasites became necrotic and amorphous. Pathologically the lesions appeared as eosinophilic masses and neutrophile leukocytes were infiltrated surrounding the masses. In some cases, the dead worms were found apart from the original place of inoculation but no leukocyte infiltration was found. There was linear infiltration between the original site and the portion where the dead worm was found. The distance from the capsule varied from 0 to 4 mm. Sometimes, the eggs of Clonorchis sinensis were also found. In all cases, there were no living worms in liver tissues and hepatic ducts. In all case,. the bacteriological examination was negative. Do clonorchis sinensis transfer the microorganism? Five adult worms of clonorchis sinensis were incubated in the saline solution containing Staphylococcus aureus. The intestinal contents of these worms were cultured in the Nutient-agar plate and examined by Methylene Blue and Gram's stain. The area of liver tissue where the Clonorchis sinensis were inoculated showed no inflammatory changes after the 3 days of inoculation but no living Staphylococcus aureus was found in the culture media with which the pieces of liver tissues were smeared. Hookworm: Cutaneous infection: Four to eight days after the cutaneous infection of Ancylostoma caninum, the mice were sacrificed. Grossly, there was no abnormal finding in liver. The pieces of liver tissues were smeared on the Nutrient-agar plate, and cocci were found in four out of six examined. The microorganism were confirmed as the same species of Diplococcus pneumoniae which were grown in the hookworm culture media. Oral infection: 1,000 filariform larvae of Ancylostoma caninum were given orally. 24 hours later, the mice were sacrificed and the pieces of liver tissue were smeared on the Nutrient-agar plate. After 50 hours at 36 C, the bacterial colonies were examined bacteriologically. Staphylococcus albus was found from two out of four samples. Grossly there was no abnormality on the surface of liver, but microscopically there were spots like microabscesses which were infiltrated by leukocytes. The larvae were also found from other portions of liver tissues and they were surrounded by yellow colored material. In another experiment, a combination of Ancylostoma duodenale and Staphylococcus aureus was fed to mice. The mice sacrificed five days after the oral administration of Ancylostoma duodenale cultivated in the media containing Staphylococcus aureus. The liver pieces were examined routinely. The larvae cultivated in normal tap water which contained no Staphylococcus aureus was used as control. In the experimental mouse, the cocci appeared in the liver. Pathologically, microabscesses infiltrated with neutrophile leukocytes were found, but there was no manifestation of inflammatory change due to Staphylococcus aureus. There was only mechanical trauma due to the larvae penetration. Haemorrhage appeared only where the larvae were found.
parasitology-helminth-trematoda-nematoda ; Clonorchis sinensis ; Ancylostoma caninum ; pathogenicity ; Staphyllococcus aureus ; Staphyllococcus albus ; Diplococcus pneumoniae ; rabbit-liver

In Southeast Asia, a total of 59 species of foodborne intestinal flukes have been known to occur in humans. The largest group is the family Heterophyidae, which constitutes 22 species belonging to 9 genera (Centrocestus, Haplorchis, Heterophyes, Heterophyopsis, Metagonimus, Procerovum, Pygidiopsis, Stellantchasmus, and Stictodora). The next is the family Echinostomatidae, which includes 20 species in 8 genera (Artyfechinostomum, Acanthoparyphium, Echinochasmus, Echinoparyphium, Echinostoma, Episthmium, Euparyphium, and Hypoderaeum). The family Plagiorchiidae follows the next containing 5 species in 1 genus (Plagiorchis). The family Lecithodendriidae includes 3 species in 2 genera (Phaneropsolus and Prosthodendrium). In 9 other families, 1 species in 1 genus each is involved; Cathaemaciidae (Cathaemacia), Fasciolidae (Fasciolopsis), Gastrodiscidae (Gastrodiscoides), Gymnophallidae (Gymnophalloides), Microphallidae (Spelotrema), Neodiplostomidae (Neodiplostomum), Paramphistomatidae (Fischoederius), Psilostomidae (Psilorchis), and Strigeidae (Cotylurus). Various types of foods are sources of human infections. They include freshwater fish, brackish water fish, fresh water snails, brackish water snails (including the oyster), amphibians, terrestrial snakes, aquatic insects, and aquatic plants. The reservoir hosts include various species of mammals or birds.The host-parasite relationships have been studied in Metagonimus yokogawai, Echinostoma hortense, Fasciolopsis buski, Neodiplostomum seoulense, and Gymnophalloides seoi; however, the pathogenicity of each parasite species and host mucosal defense mechanisms are yet poorly understood. Clinical aspects of each parasite infection need more clarification. Differential diagnosis by fecal examination is difficult because of morphological similarity of eggs. Praziquantel is effective for most intestinal fluke infections. Continued efforts to understand epidemiological significance of intestinal fluke infections, with detection of further human cases, are required.
Animals ; Asia, Southeastern/epidemiology ; *Food Parasitology ; Humans ; Intestines/*parasitology ; Trematoda/classification/genetics/*isolation & purification/pathogenicity ; Trematode Infections/diagnosis/*epidemiology/*parasitology/therapy

The intestinal histopathology and in situ postures of Gymnophalloides seoi (Digenea: Gymnophallidae) were studied using C3H/HeN and C57BL/6 mice as experimental hosts; the effects of immunosuppression were also observed. The metacercariae isolated from naturally infected oysters, 300 or 1,000 in number, were infected orally to each mouse, and the mice were killed at days 3-21 post-infection (PI). In immunocompetent (IC) mice, only a small number of flukes were found in the mucosa of the duodenum and jejunum during days 3-7 PI, with their large oral suckers pinching and sucking the root of villi. The intestinal mucosa showed mild villous atrophy, crypt hyperplasia, and inflammations in the villous stroma and crypt, with remarkable goblet cell hyperplasia. These mucosal changes were almost restored after days 14-21 PI. In immunosuppressed (IS) mice, displacement as well as complete loss of villi adjacent to the flukes was frequently encountered, otherwise the histopathology was generally mild, with minimal goblet cell hyperplasia. In these mice, numerous flukes were found, and it seemed that they were actively moving and rotating in situ. Several flukes were found to have invaded into the submucosa, almost facing the serosa. These results indicate that in IC mice the intestinal histopathology caused by G. seoi is generally mild, and the flukes do not penetrate beyond the mucosa, however, in IS mice, the flukes can cause severe destruction of neighboring villi, and some of them invade into the submucosa.
Animals ; Atrophy ; Immunocompromised Host ; Intestinal Diseases, Parasitic/*parasitology/pathology ; Intestinal Mucosa/parasitology/*pathology ; Male ; Mice ; Mice, Inbred C3H ; Mice, Inbred C57BL ; Support, Non-U.S. Gov't ; Trematoda/*pathogenicity ; Trematode Infections/*parasitology/pathology

Metacercariae of Gynaecotyla squatarolae (Digenea: Microphallidae) were discovered from the shore crab, Macrophthalmus dilatatus, purchased at a market in a coastal town of Taean-Eup, Chungcheongnam-do, Republic of Korea. Their adult flukes were confirmed by experimental infection of rats. The metacercariae of G. squatarolae were elliptical (391.1 x 362.5 micrometer), and the excysted metacercariae had progenetic genital organs, including the ovary and testes. To obtain adult flukes, 6 Sprague-Dawley rats were fed 500 metacercariae each, and killed at days 2, 4, and 6 post-infection. The adult flukes were identified as G. squatarolae (Yamaguti, 1934) Yamaguti, 1939, based on morphological characters, including 2 ventral suckers (1 large and 1 small), a large genital atrium equipped with the cirrus and the metraterm, separated male and female genital pores, a transversely long cirrus pouch, and extensive vitelline follicles. In the present study, it has been first proven that the shore crab M. dilatatus is a second intermediate host for G. squatarolae in the Republic of Korea.
Animals ; Brachyura/*parasitology ; Female ; Host-Parasite Interactions ; Korea ; Life Cycle Stages/physiology ; Male ; Rats ; Rats, Sprague-Dawley ; Time Factors ; Trematoda/*anatomy & histology/isolation & purification/*pathogenicity ; Trematode Infections/parasitology/*veterinary