Giant liver fluke
| Giant liver fluke | ||||||||||||
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Drawing from the first description, left back view (red blood circulation), right stomach view (blue digestive tract) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Fasciola gigantica | ||||||||||||
| ( Cobbold , 1855) |
The giant liver fluke ( Fasciola gigantica ) is a parasitic suction worm that infects the livers of ruminants (especially domestic cattle and buffalo , more rarely also sheep and goats ). Occasionally, other herbivores such as horses and humans are also attacked. The giant liver fluke is the causative agent of tropical fasciolosis .
The giant liver fluke occurs in the tropical and subtropical areas of Africa and Asia. In Africa it is mainly distributed south of the Sahara , in Asia from Turkey to the Philippines .
features
The giant liver fluke is a leaf-like suction worm. At 24 to 75 mm, it is slightly longer and at 5 to 12 mm wide, a bit narrower than its closest relative, the great liver fluke . The apical cone is shorter, the rear end somewhat rounder.
At 150–190 µm × 90–100 µm, the eggs are somewhat larger than those of the great liver fluke, but cannot be distinguished from them morphologically.
Development cycle
An adult liver fluke lays eggs in the bile duct system of the definitive host, which are released into the environment with the faeces . These eggs survive there for several months. The eyelash larvae ( miracidia ) hatch from the eggs at 25 ° C after about three weeks . After hatching, the eyelash larvae swim with the help of their cilia until they find an intermediate host. Amphibious mud snails of the genus Radix act as intermediate hosts .
In the snail, the eyelash larvae develop into tail larvae ( cercaria ) within a month . These actively leave the snail. About a third of the cercaria develop into swimming cysts ( metacercariums ), which probably play a greater role in the spread than the cercaria attached to the plants. Metacercariae can remain infectious on plants for up to six months. After being absorbed by the ultimate host, the cercariae pierce the intestinal wall and colonize the bile duct system of the liver, where they develop into adults. The prepatent period lasts 13 to 16 weeks. Within the final host, the parasite usually only survives for one year, rarely up to four years.
Web links
literature
- Johannes Eckert: textbook of parasitology for veterinary medicine . Georg Thieme, 2008, ISBN 9783830410720 , p. 164.