Question

Immediate evisceration of captured fish and cooking or freezing fish product prior to consumption is recommended for prevention of which zoonotic parasitic disease?
A. Opisthorchis viverrini
B. Clonorchis sinensis
C. Anisakis simplex
D. Diphyllobothrium latum

• A. Opisthorchis viverrini
• B. Clonorchis sinensis
• C. Anisakis simplex
• D. Diphyllobothrium latum

Hint:

Anisakis is unique because its zoonotic larvae migrate from the viscera to the muscle *after* the host fish dies.
Thus, "immediate evisceration" (removing the gut before migration occurs) is a highly specific control strategy for Anisakis simplex compared to other fish-borne parasites.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Anisakiasis is a zoonotic parasitic disease of humans caused by the ingestion of larval nematodes belonging to the family Anisakidae, primarily Anisakis simplex, through raw or undercooked marine fish.

Step 2: Detailed Explanation:
Let us examine the biological behavior of Anisakis simplex larvae and how preventive measures target it:
- Larval migration: In living marine fish, third-stage larvae (\(L_3\)) of Anisakis simplex reside primarily within the visceral organs and body cavities of the fish.
- Post-mortem migration: Upon the death of the fish host, the rise in temperature and changes in tissue chemistry trigger the larvae to actively migrate from the viscera into the surrounding skeletal muscles (the edible flesh of the fish).
- Evisceration: Immediate gutting and evisceration of the fish on board the fishing vessel or shortly after capture removes the viscera before the larvae have a chance to migrate into the flesh.
- Freezing and Cooking: Larvae remaining in the muscle are highly sensitive to thermal extremes.
Freezing at \(-20^\circ\text{C}\) for at least 24 hours or cooking to an internal temperature of at least \(60^\circ\text{C}\) reliably destroys the larvae, preventing human infection.
- Other parasites listed, like Clonorchis, Opisthorchis, and Diphyllobothrium, have infective stages (metacercariae or plerocercoids) that develop directly in the musculature during the life of the fish, so immediate post-mortem evisceration does not prevent their transmission.

Step 3: Final Answer:
The preventive guidelines described are specifically targeted against the post-mortem migratory behavior of Anisakis simplex larvae.
Therefore, the correct option is (C).