Trematodes upload 2010
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This is a short version of the Trematode presentation. I only include the slides containing the most important information. - May 2010.
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Trematodes upload 2010
- 1. Trematodes For educational purpose only. No copyright infringement intended. All images belong to their respective owners.
- 2. Slide preparations Fasciola hepatica (egg, adult) Paragonimuswestermanitelur Opistorchis (egg, adult) Clonorchissinensis (egg, adult) Schistosomamansoni Schistosomajaponicum Schistosomahaematobium Redia SerkariaSchistosoma
- 3. Allen G.P. Ross, Ph.D., Paul B. Bartley, M.B., B.S., Adrian C. Sleigh, M.B., B.S., M.D., G. Richard Olds, M.D., Yuesheng Li, M.D., Ph.D., Gail M. Williams, Ph.D., and Donald P. McManus, Ph.D., D.Sc. Schistosomiasis. N EnglJ Med, Vol. 346, No. 16 April 18, 2002
- 4. Clinical manifestations of schistosomiasis Allen G.P. Ross, Ph.D., Paul B. Bartley, M.B., B.S., Adrian C. Sleigh, M.B., B.S., M.D., G. Richard Olds, M.D., Yuesheng Li, M.D., Ph.D., Gail M. Williams, Ph.D., and Donald P. McManus, Ph.D., D.Sc. Schistosomiasis. N EnglJ Med, Vol. 346, No. 16 April 18, 2002
- 5. Gastrointestinal and Liver Disease Most granulomas develop at the sites of maximal accumulation of eggs: the intestine and the liver (S. mansoniand S. japonicum) the genitourinary tract (in the case of S. haematobium) Eggs retained in the gut wall induce inflammation, hyperplasia, ulceration, microabscess formation, and polyposis. Eggs of S. mansoniand S. japonicumembolize to the liver: granulomatous inflammatory response: presinusoidal inflammation periportal fibrosis periportal collagen deposits progressive obstruction of blood flow portal hypertension ultimately varices, variceal bleeding, splenomegaly, and hypersplenism Allen G.P. Ross, Ph.D., Paul B. Bartley, M.B., B.S., Adrian C. Sleigh, M.B., B.S., M.D., G. Richard Olds, M.D., Yuesheng Li, M.D., Ph.D., Gail M. Williams, Ph.D., and Donald P. McManus, Ph.D., D.Sc. Schistosomiasis. N EnglJ Med, Vol. 346, No. 16 April 18, 2002
- 6. Mostly involved in pathogenesis of venous obstruction in schistosomiasis: Portal veins Splenic veins Esophageal veins Rectal veins Mesenteric veins
- 7. Dermatitis in schistosomiasis patient http://img.medscape.com/pi/emed/ckb/pediatrics_general/996090-999469-98.jpg
- 8. Dermatitis in schistosomiasis patient http://upload.wikimedia.org/wikipedia/commons/5/5a/Cercarial_dermatitis_lower_legs.jpg
Editor's Notes
- N Engl J Med, Vol. 346, No. 16·April 18, 2002
- The adult flukes deposit fully developed eggs that are passed in the feces . After ingestion by a suitable snail (first intermediate host) , the eggs release miracidia , which undergo in the snail several developmental stages (sporocysts , rediae , cercariae ). Cercariae are released from the snail and penetrate freshwater fish (second intermediate host), encysting as metacercariae in the muscles or under the scales . The mammalian definitive host (cats, dogs, and various fish-eating mammals including humans) become infected by ingesting undercooked fish containing metacercariae. After ingestion, the metacercariaeexcyst in the duodenum and ascend through the ampulla of Vater into the biliary ducts, where they attach and develop into adults, which lay eggs after 3 to 4 weeks . The adult flukes (O. viverrini: 5 mm to 10 mm by 1 mm to 2 mm; O. felineus: 7 mm to 12 mm by 2 mm to 3 mm) reside in the biliary and pancreatic ducts of the mammalian host, where they attach to the mucosa.
- Embryonated eggs are discharged in the biliary ducts and in the stool . Eggs are ingested by a suitable snail intermediate host . Each egg releases a miracidia , which go through several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and after a short period of free-swimming time in water, they come in contact and penetrate the flesh of freshwater fish, where they encyst as metacercariae . Infection of humans occurs by ingestion of undercooked, salted, pickled, or smoked freshwater fish . After ingestion, the metacercariaeexcyst in the duodenum and ascend the biliary tract through the ampulla of Vater . Maturation takes approximately 1 month. The adult flukes (measuring 10 to 25 mm by 3 to 5 mm) reside in small and medium sized biliary ducts. In addition to humans, carnivorous animals can serve as reservoir hosts.
- The eggs are excreted unembryonated in the sputum, or alternately they are swallowed and passed with stool . In the external environment, the eggs become embryonated , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues . Miracidia go through several developmental stages inside the snail : sporocysts , rediae , with the latter giving rise to many cercariae , which emerge from the snail. The cercariae invade the second intermediate host, a crustacean such as a crab or crayfish, where they encyst and become metacercariae. This is the infective stage for the mammalian host . Human infection with P. westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite . The metacercariaeexcyst in the duodenum , penetrate through the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults (7.5 to 12 mm by 4 to 6 mm). The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively. However, when this takes place completion of the life cycles is not achieved, because the eggs laid cannot exit these sites. Time from infection to oviposition is 65 to 90 days. Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P. westermani.