Question

During its life-cycle, Fasciola hepatica (liver fluke) infects its intermediate host and primary host at the following larval stage respectively

• A. Redia and miracidium
• B. Cercaria and redia
• C. Metacercaria and cercaria
• D. Miracidium and metacercaria

Answer 1

Answer: (D)

Miracidium and metacercaria

Answer 2

The larval stages and hosts in the life cycle are as follows:
1. Eggs are passed in the feces of the primary host (usually a mammal, such as a sheep or cow).
2. Miracidium hatches from the egg and infects the intermediate host, which is usually a freshwater snail.
3. Inside the snail, the miracidium undergoes several developmental stages, including sporocysts and rediae.
4. Rediae give rise to cercariae, which are the free-swimming larval stage.
5. Cercariae are released from the snail and encyst as metacercariae on aquatic vegetation.
6. The primary host ingests the metacercariae by consuming contaminated vegetation.
7. Inside the primary host's digestive system, metacercariae excyst and develop into adult liver flukes.

So, the correct answer is (D): Miracidium and metacercaria