Question

Fasciola hepatica is an endoparasite that lives in the -----of sheep.
A. Liver
B. Blood
C. Spleen
D. Intestine

Answer 1

Fasciola hepatica is commonly known as common liver fluke or sheep liver fluke. The fluke causes a disease called fasciolosis. Its life cycle is complete in two host organisms.

Complete answer:
-It is one of the largest fluke in the world where it has a length of 30mm and a diameter of 13mm and it is leaf shaped and is nailed at the back side and wide in the front portion. The outer surface of the fluke is called tegument.
-Fasciola hepatica is an endoparasite which is of class Trematoda, phylum Platyhelminthes. The liver of many mammals are stressed by this parasite. The fluke causes a disease called fasciolosis. It is classified as Foodborne disease. As it is an endoparasite which is found in the liver of the host and its lifecycle is of indirect type.
-Cattles, sheeps, buffaloes are the host of the fluke. Its lifecycle consists of an intermediate host and several environmental larval stages. Intermediate hosts are air breathing freshwater snails which belong to the family Lymnaeidae.
-Freshwater snail releases metacercariae as cercariae which forms a cyst on various surfaces which includes the aquatic vegetation. This vegetation is consumed by mammals and thus they get infected. By this way the parasite enters the mammals body and is thus called endoparasite.
-When coming to the life cycle of Fasciola hepatica, it completes its life cycle mainly in two hosts, the first one is a vertebrate host or sheep and the second one is an intermediate host which can be invertebrate like Mollusca.
-It can cause sudden death in sheep and cattles by liver damage or internal hemorrhage. Depending on either the infection the symptoms may be acute or chronic and vary in humans.
-When coming to the symptoms of Fasciola hepatica, it blocks the bile duct, causes fever and results in abnormalities in the liver.

Hence, the correct answer is option (A).

Note: The person is infected when he consumed cyst covered vegetation. Cilia and flagella like tails in larvae and cercariae helps them to swim through the aquatic environment and thus reach the plants where they form a cyst.