Ques. 1AIPMT 2003
During the life-cycle, Fasciola hepatica (liver fluke) infects its intermediate host and primary host at the following larval stages respectively
- redia and miracidium
- cercaria and redia
- metacercaria and cercaria
- miracidium and metacercaria
Answer
(4) miracidium and metacercaria
Solution
Eggs of Fasciola hepatica hatch in water into the free-swimming ciliated miracidium larva.
The miracidium penetrates the snail (intermediate host) and develops into sporocyst → redia → cercaria.
Cercariae then leave the snail and encyst on grass as metacercariae, and sheep (primary host) are infected when they eat grass carrying metacercariae.
∴ Intermediate host: miracidium; primary host: metacercaria.
Answer: (4)