Anisakiasis

Anisakiasis (also known as anisakidosis or herring worm disease) is a parasitic infection caused by the ingestion of larvae of nematodes belonging to the family Anisakidae, most commonly Anisakis simplex and Pseudoterranova decipiens. Humans become accidental hosts by consuming raw or undercooked seafood (such as sushi, sashimi, ceviche, or pickled fish) contaminated with third-stage larvae. The disease is not genetically inherited but is an acquired zoonotic infection. The larvae primarily affect the gastrointestinal system. After ingestion, the larvae can penetrate the mucosa of the stomach (gastric anisakiasis) or intestine (intestinal anisakiasis), causing acute symptoms including severe epigastric or abdominal pain, nausea, vomiting, and diarrhea, typically occurring within hours to days after consuming contaminated fish. In some cases, the larvae can trigger significant allergic reactions, including urticaria, angioedema, and even anaphylaxis. Chronic infection may lead to granuloma formation in the gastrointestinal wall, which can mimic tumors or Crohn's disease. Rarely, ectopic forms occur when larvae migrate to other tissues outside the gastrointestinal tract. Diagnosis is typically made through endoscopic visualization and removal of the larvae from the gastric or intestinal mucosa, or through histopathological examination of surgically removed tissue. Treatment of choice is endoscopic extraction of the larvae, which provides both diagnosis and cure. In cases where endoscopic removal is not possible, conservative management with supportive care may be employed, as the larvae cannot survive long-term in the human host. Albendazole has been used in some cases, though its efficacy is not well established. Prevention is the most effective strategy, involving thorough cooking of fish (to at least 60°C) or freezing at -20°C for at least 24 hours before consumption. The disease is most prevalent in regions where raw fish consumption is common, particularly Japan, but cases are increasingly reported in Europe, South America, and other regions worldwide.

Common questions about Anisakiasis