Question

At which stage, do the Fasciolopsis exit the snail body?
A. Redia
B. Cercaria
C. Metacercaria
D. Miracidium

Answer 1

Fasciolopsis buski is an intestinal fluke occurring in human beings and requires a snail intermediate host for completion of its life cycle.

Complete answer:
The life cycle of Fasciolopsis buski starts when immature and unembryonated eggs are released into the intestine and the faeces.

Option A: Redia larva emerges from sporocyst i.e.second larva and feeds upon the host's tissue.

Option B: Cercaria larva is formed in the body of redia larva. It leaves the body of redia and ultimately escapes the host body in surrounding water (Temperature between 9°C-26°C favours the emergence of cercaria from snail).

Option C: The Cercaria swims in surrounding water and later on becomes inactive to form metacercaria larva. The larva is encysted, so when the definitive host feeds on, then migrate to the host intestine, and develop into an adult.

Option D: A single snail intermediate host, which becomes infected when eggs excreted in the feces of an infected human hatch to release a miracidium and become embryonated within two weeks.

Thus, the correct option is B) Cercaria.

Note: Intestinal flukes (trematodes) are flat hermaphroditic worms that range in size from a few millimeters to several centimeters. Approximately 70 trematode species have been reported to colonize the human intestinal tract.