Fasciola hepatica Life Cycle Quiz

Infective Stage

• The infective stage of Fasciola hepatica is the metacercaria, a larval stage.
• Metacercariae are found encysted on aquatic vegetation, such as watercress.
• Humans or other mammals become infected by consuming contaminated water plants.

Intermediate Host

• The intermediate host for Fasciola hepatica is a mollusk, typically a species of Lymnaea.
• The parasite enters the mollusk, developing into a cercaria.

Development in the Intermediate Host

• Once inside the mollusk, the parasite undergoes development.
• This development leads to the production of free-swimming cercariae.
• The cercariae penetrate and encyst on water plants, transforming into metacercariae.

Penetration of Definitive Host

• The metacercariae are ingested by a definitive host (e.g., sheep, cattle, humans).
• Following ingestion, the metacercariae excyst in the small intestine.

Excystment and Migration

• The excystment occurs in the small intestine.
• The young fluke migrates through the intestinal wall.
• It then travels through the peritoneal cavity to the liver.

Development in the Liver

• The flukes migrate through the bile duct system of the liver.
• They begin to mature and grow.
• During this stage, the flukes develop their characteristic body shape.

Adult Flukes

• Adult flukes are hermaphroditic, meaning they possess both male and female reproductive organs.
• Once mature, they begin mating and producing eggs.

Egg Production and Release

• Adult flukes produce numerous eggs within the bile duct system.
• These eggs are released into the bile ducts.
• The eggs eventually pass into the feces.

Egg Fate and Lifecycle Continuation

• Eggs excreted in the feces, if released into suitable aquatic environments, hatch.
• The eggs release miracidia, which infect intermediate hosts (mollusks).
• The parasite continues its life cycle repeating the process.