Anisakidae

Anisakidae

Anisakis simplex, a common species of Anisakidae

The Anisakidae is a family of parasitic nematodes that primarily infect marine mammals, fish, and birds. These worms belong to the phylum Nematoda and are commonly known as anisakid worms. They are found in various marine environments worldwide, including both saltwater and freshwater habitats.

Taxonomy

The family Anisakidae is classified under the order Ascaridida, which includes other parasitic nematodes. It is further divided into several genera, including Anisakis, Pseudoterranova, and Contracaecum. Each genus consists of multiple species, with Anisakis simplex being one of the most well-known and widely studied species within the family.

Morphology

Anisakid worms have a cylindrical body shape, typically measuring a few centimeters in length. They possess a well-developed digestive system, reproductive organs, and sensory structures. The anterior end of the worm is characterized by a mouth surrounded by three lips, which are used for feeding and attachment to the host's intestinal wall.

Life Cycle

The life cycle of Anisakidae involves multiple hosts. Adult worms reside in the stomach and intestines of marine mammals, such as whales or seals, where they reproduce and release eggs into the water through the host's feces. These eggs hatch into larvae, which are then ingested by intermediate hosts, usually fish or squid.

Once inside the intermediate host, the larvae penetrate the intestinal wall and migrate to various organs, including the muscle tissue. This migration can cause the formation of cysts, which are visible to the naked eye. When a predator consumes the infected intermediate host, the larvae are released into the predator's digestive system, completing the life cycle.

Pathology

Anisakid infections in humans are primarily caused by the consumption of raw or undercooked seafood containing infective larvae. When ingested, the larvae can penetrate the gastrointestinal tract, leading to symptoms such as abdominal pain, nausea, vomiting, and diarrhea. In some cases, severe allergic reactions or intestinal obstruction may occur.

Prevention and Control

To prevent Anisakidae infections, it is recommended to thoroughly cook seafood, as heat kills the larvae. Freezing seafood at temperatures below -20°C (-4°F) for a specific duration can also effectively kill the larvae. Additionally, proper handling and storage of seafood can help reduce the risk of contamination.

See Also

• Nematoda
• Parasitism
• Marine Biology