Question

Life cycle is ‘digenetic' in _____
a. Taenia solium
b. Fasciola hepatica
c. Taenia saginata
d. All of the above

Answer 1

Hint: Digenetic life cycle: In this type of cycle two hosts are required by an organism to complete its life cycle. For example in the life cycle of Plasmodium humans and mosquitoes are required for the completion of their life cycle. Digenetic life cycles of trematodes are complex as the organisms undergo several morphological changes. The cycles have two steps. One sexual in mature forms and another one is asexual in the larval stages. The beginning of the life cycle occurs with the egg which directly hatches into the environment, some are eaten by the host and get hatched in their body (Mollusc).

Complete answer:
> Taenia solium:
T.solium infection is a human intestinal part. The worm is sexual in the mature and asexual in the larval stage. With adult tapeworm that follows the ingestion of contaminated pork. Cysticercosis is an infection with larvae of T.solium. which develops. After an ova increase in human feces. Adult worms cause mild gastrointestinal symptoms. And the passage of a motile segment in the stool. Length of adult worm 2 to 7m.

> Fasciola hepatica:
Immature Fasciola eggs are discharged from the biliary ducts and the stool.
1. The eggs become embryonated in water
2. Eggs are release miracidia
3. Suitable snail intermediate host
4. including, Galba, Fossaria, and Pseudosuccinea.

> Taenia saginata:
Taeniasis is the infection of the human intestinal with the adult tapeworm of T.saginata or T.solium. T.saginata and T.solium only definitive host for the Human intestinal. Eggs or gravid proglottids are passed with stool. The eggs survive for the days to months in the environment. Length of adult worm 5m or less for T.saginata. It also requires two hosts so its life cycle is also a digenetic type.

Hence, the correct answer is option (D).

Additional information:
- Taenia solium and Taenia saginata are the tapeworm species that cause parasitic infection in human beings.
- The common name of Taenia solium is pork tapeworm and Taenia saginata is a beef tapeworm.
- Another name for F. hepatica is a common liver fluke or sheep liver fluke.
- It is a trematode parasite that infects the liver of the host mammals.
- Infection or disease caused by Fasciola hepatica is known as fasciolosis.
- It is the main parasite of cattle and sheep.

Note: The digenetic life cycle involves two hosts to complete its life cycle. Trematodes infect all the vertebrates and in turns lead to the threat to economic activities for eg fishing, aquaculture, and animal husbandry. Taenia solium, Taenia saginata, and Fasciola hepatica all are parasites that cause parasitic infection in the hosts including human beings. Common fluke causes the infection of the liver as it directly infects the liver of the host. All of these three tapeworms require two hosts for their life cycle so all have a digenetic life cycle.