Question

Match List-I with List-II: 

List-I (Parasite)	List-II (Metacestode stage)
(A) Taenia multiceps	(I) Cysticercus tenuicollis
(B) Mesocestoides ambiguus	(II) Tetrathyridium
(C) Taenia hydatigena	(III) Strobilocercus
(D) Taenia taeniaeformis	(IV) Coenurus

Choose the correct answer from the options given below:

• (A) - (IV), (B) - (II), (C) - (I), (D) - (III)
• (A) - (I), (B) - (III), (C) - (II), (D) - (IV)
• (A) - (II), (B) - (I), (C) - (III), (D) - (IV)
• (A) - (III), (B) - (IV), (C) - (I), (D) - (II)

Hint:

Remember that Taenia multiceps is the classic cause of "gid" or "sturdy" in sheep, which is caused by the Coenurus bladder in the brain (A-IV). Matching this first helps eliminate other options.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Cestodes (tapeworms) have an indirect life cycle requiring intermediate hosts, where the ingested oncosphere develops into a larval stage known as a metacestode.
The morphology and name of the metacestode stage are highly specific to each tapeworm species.

Step 2: Detailed Explanation:
Let us match each adult tapeworm with its larval (metacestode) stage:
- Taenia multiceps (A): The adult worm resides in the intestines of canids. The metacestode stage develops in the central nervous system of sheep and goats, forming a fluid-filled bladder containing multiple invaginated scolices, known as a Coenurus (specifically Coenurus cerebralis). This matches with (IV).
- Mesocestoides ambiguus (B): The larval stage of this tapeworm is a solid-bodied, elongated, and highly contractile worm-like structure known as a Tetrathyridium, which is found in the peritoneal cavity of lizards, rodents, or dogs. This matches with (II).
- Taenia hydatigena (C): The adult worm resides in canids. The metacestode stage is a large, single-scolex bladder-worm found attached to the peritoneal cavity or liver of ruminants and pigs, known as Cysticercus tenuicollis. This matches with (I).
- Taenia taeniaeformis (D): The adult resides in cats. The metacestode stage develops in rodents and is characterized by a bladder-worm that has already begun to segment and form a larval body, known as a Strobilocercus (specifically Strobilocercus fasciolaris). This matches with (III).
Combining these individual linkages, the matching sequence is (A) - (IV), (B) - (II), (C) - (I), (D) - (III).

Step 3: Final Answer:
The matching sequence is represented by option (A).