Liver Flukes Flashcards
What are the two species of liver flukes discussed in the document?
Fasciola hepatica and Fasciola gigantica.
What is the common name for Fasciola hepatica?
Sheep liver fluke or liver fluke.
What are the definitive hosts for Fasciola hepatica?
Sheep, goat, cattle, or man.
What is the intermediate host for Fasciola hepatica?
Snails of the genus Lymnaea.
What is the infective stage of Fasciola hepatica?
Metacercariae.
What is the diagnostic stage for Fasciola hepatica infection?
Unembryonated egg.
Where is the natural habitat of adult Fasciola hepatica in the host?
Bile duct and gallbladder.
How is Fasciola hepatica transmitted to humans?
By eating water plants and watercress containing metacercariae.
Describe the egg of Fasciola hepatica.
Large, operculated, ovoid in shape, brownish yellow in colour (bile stained). Size 140 µm by 80µm. Contains a large unsegmented ovum in a mass of yolk cells.
Describe the miracidium stage of Fasciola hepatica.
Ciliated, retractile papillae (anterior), secretory glands (pairs) (anterior), primitive gut with anterior mouth, germinal cells posterior, eye spots anterior.
Describe the redia stage of Fasciola hepatica.
1.5 mm length, primitive gut anteriorly, germinal cells posteriorly, lateral appendages.
Describe the cercaria stage of Fasciola hepatica.
Unforked tail, bear shape anteriorly and tail-like shape posteriorly, digestive tract in anterior part, secretory cephalic gland anteriorly, germinal cells posteriorly.
Describe the adult Fasciola hepatica worm.
Large in size (3 cm length by 1.2 cm breadth), flat, leaf-shaped, brown colored. The anterior end has a conical projection (shoulder). Oral and ventral suckers. Intestine is bifurcated and bears lateral branches. Both male and female reproductive organs.
How does Fasciola gigantica differ in size from Fasciola hepatica?
Fasciola gigantica measures up to 75mm in length and 12mm in width, making it the largest of the human liver and lung flukes.
Describe the morphological differences between Fasciola gigantica and Fasciola hepatica.
Fasciola gigantica tends to be more oblong with a longer rounded posterior end compared to the broadly pointed posterior end of F. hepatica. It has a shorter cephalic cone, a larger ventral sucker, and a more anterior position of the testes.
What is the method of choice for diagnosing Fasciola infection?
Stool microscopy to detect operculated eggs.
What happens after the metacercariae are ingested by the definitive host?
They excyst in the duodenum and migrate to the hepatic biliary ducts, where they mature into adults.
Where do the cercariae encyst to become metacercariae?
On water plants.
What stage hatches from the embryonated eggs in water?
Miracidia.
What do the miracidia do after hatching?
They penetrate the snail (intermediate host).
