Friday, February 2, 2024

Infective stage of Taenia.. Embryonated egg

Infective stage of Taenia:

  • A- Larva
  • B- Cercaria
  • C- Embryonated egg
  • D- Cyst
  • E- Metacercaria.

For Taenia species like Taenia solium (pork tapeworm) and Taenia saginata (beef tapeworm), the infective stage is indeed: D- Cyst

Here's why the other options are not correct:

A- Larva:

While larvae exist in the Taenia life cycle, they develop inside the cyst and are not directly infective.

B- Cercaria:

This term applies to flatworm parasites, not tapeworms like Taenia.

C- Embryonated egg:

Although Taenia eggs contain embryos, they need further development inside an intermediate host (pig for T. solium and cow for T. saginata) before becoming infective cysts.

E- Metacercaria:

This term describes a specific larval stage in flatworms, not tapeworms.

The infective stage of Taenia is the cysticercus, also known as a "bladder worm." This encapsulated larva develops within the muscle tissue of the intermediate host and contains a scolex (head) of the adult tapeworm. When humans ingest undercooked infected meat, the cysts break open, releasing the scolex which attaches to the small intestine and matures into an adult tapeworm.
Therefore, D- Cyst is the accurate answer for the infective stage of Taenia.