Question

The infective stage of Fasciola hepatica to sheep is
A. Sporocyst
B. Cercaria
C. Metacercariae
D. Hexacanth

Answer 1

Hint:-A parasitic trematode (flatworm) of the Trematoda genus, phylum Platyhelminthes, is Fasciola hepatica, also known as the common liver fluke or sheep liver fluke. It infects the livers, like humans, in different mammals.

Complete step-by-step solution:-
In the liver of a definitive host, Fasciola hepatica occurs and its lifecycle is indirect. The fluke 's definitive hosts are goats, sheep, and buffaloes. As definitive hosts, wild ruminants and other animals , including humans, may also function. The cycle of life of Fasciola hepatica progresses through the intermediate host and multiple larval phases of the environment. F's intermediate hosts. Hepatica are freshwater air-breathing snails belonging to the Lymnaeidae tribe.

Life cycle
Over ~ 2 weeks, eggs become embryonated in freshwater.
1. Release miracidia from embryonated eggs
2. Invade a sufficient intermediate host of snails.
3. The parasites undergo multiple developmental stages in the snail (sporocysts, rediae and cercariae)
4. The snail releases the cercariae.
5. Encyst as metacercariae on or on other substrates in marine plants. By ingesting metacercariae-contaminated vegetation, humans and other mammals get sick.
6. Excyst of metacercariae in the duodenum following ingestion.
7. Penetrate into the peritoneal cavity from the gut wall. Then, the juvenile flukes migrate through biliary ducts via the liver parenchyma, where they develop through adult flukes and produce eggs.
8. In humans, it typically takes around 3-4 months to mature from metacercariae into adult flukes; Fasciola gigantica may take much longer to grow than Fasciola hepatica.

Here we can conclude that the infective stage of Fasciola hepatica to sheep is metacercariae. Therefore the correct answer is option (C).

Note:- Fasciola hepatica, which is transmitted worldwide, has been known for decades as an important sheep and cattle parasite and causes major economic losses for these species of livestock. It has been the focus of many experimental studies due to its comparatively large scale and economic importance and may be the best known of any trematode genus. The nearest relative to Fasciola hepatica is Fasciola gigantica.