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Liver flukes

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الكلية كلية الصيدلة     القسم  فرع البايولوجي     المرحلة 2
أستاذ المادة رشا هادي صالح عبد العيساوي       10/03/2018 14:04:59
Liver flukes

Liver flukes are parasite that localized in liver and biliary passage of various mammalians. Human liver flukes of two families, the opisthorchidae and the Fasciolidae. Opisthorchiidae has three species(Clonorchis sinensis, Op.viverrini, Op.felineus). In the Fasciolide( F.gigantica and F.hepatica).

Fasciola

F. hepatica (the sheep liver fluke) and F. gigantica (mainly of cattle ) cause fascioliasis in humans. The parasites vary in adult and egg size and species of the snail host of the family Lymnaeidae. Fasciola hepatica was the largest and most common liver fluke found in humans, but its primary host is the sheep. It is worldwide in distribution, being found mainly in sheep-rearing areas. It causes the economically important disease ‘liver rot’ in sheep. Humans usually become infected by eating aquatic plants grown in water contaminated with feces from animals harbouring fasciola.

The adult worm lives in the biliary tract of the definitive host for many years about 5 years in sheep and 10 years in humans. It is a large leaf-shaped fleshy fluke, 30 mm long and 15 mm broad, grey or brown in color. It has a conical projection anteriorly and is rounded posteriorly. The eggs are large, ovoid, operculated, bile stained. They are laid in the biliary passages and shed in feces.

B A

F. hepatica(A-adult,B-egg)

Life cycle

The adult worm lives in the bile duct of the final host and immature eggs discharged in the biliary ducts are excreted in the feces of the host. The embryo matures in water in about 10 days and the miracidium escapes and invade a snail intermediate host of the genus Lymnae. In the snail the parasites undergo several developmental stages (sporocysts, rediae, and cercariae). The cercariae are released from the snail and encyst as metacercariae on aquatic vegetation or other surfaces. Sheep, cattle or humans eating water vegetation containing the metacercaria become infected. After ingestion, the metacercariae excyst in the duodenum and migrate through the intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts, where they develop into adults. In humans, maturation from metacercariae into adult flukes takes approximately 3 to 4 months.

Pathogenicity

These parasites cause considerable mortality in sheep,cattle and human.The acute phase occurs during migration of the immature flukes through the liver, it causes parenchymal injury, haemorrhage, inflammatory responses largely mediated by eosinophils. Some larvae penetrate through the liver and diaphragm ending up in the lung. Patients present initially with fever and hepatomegaly. Later they develop acute epigastric pain, obstructive jaundice and anaemia. Death is uncommon, but is caused by haemorrhaging in the bile duct.


المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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