Anisakiasis is a parasitic disease caused by anisakid nematodes (worms) that can invade the stomach wall or intestine of humans. The transmission of this disease occurs when infective larvae are ingested from fish or squid that humans eat raw or undercooked. In some cases, this infection is treated by removal of the larvae via endoscopy or surgery.
Image: Left: Coiled worms in fresh, never frozen, fillet of cod. Center: L3 larva of an anisakid worm. Right: A group of herring caught at sea. Ingesting infected fish that are raw or undercooked can lead to anisakiasis. Credit: DPDx, NEFSC/NOAA