Gastric anisakiasis: do not forget the clinical history!

Gastrointestinal anisakiasis is a parasitic disease acquired by humans after ingestion of raw fish infected with third stage larvae of the nematode Anisakis simplex. Even if considered a rare disease in Western countries, it is underestimated in many countries with large fishing-based activities and widespread consumption of raw sea food. This could also depend on the observation that the nematode is often hidden among gastric folds, and can be confused with gastric mucus. Consequently, gastric detection could be difficult, and the use of narrow band imaging (NBI) has been recently suggested to improve parasite detection at endoscopy [1]. To our knowledge, 11 cases of gastric anisakiasis have been described in Italy [1, 2]. Moreover, some cases have been reported in other European countries, such as Austria, Germany, and Spain [3-5]. We observed a patient complaining of acute epigastric pain and vomiting within 3 hours following the ingestion of uncooked anchovies. Due to persistent pain without vomiting, the patient underwent upper endoscopy 4 days later. Based on clinical history, anisakiasis was suspected and the parasite was searched for at standard endoscopy. A mobile nematode was detected (Fig. 1A), showing an extremity strongly adherent to the gastric mucosa when it was removed with a biopsy forceps (Fig. 1B). This case clearly demonstrates that anisakiasis should be promptly suspected when abdominal symptoms occur following raw fish ingestion. In addition, it highlights that the clinical history may guide the diagnosis, alerting the endoscopist to accurately search for a parasite during a standard endoscopy. Since no effective medical treatments for anisakiasis are currently available, it should be suspected at clinical history, and an accurate upper endoscopy be performed to remove the parasite.