(BMJ)—An otherwise healthy man in his 60s presented w/ severe epigastric pain 8h after eating sashimi. Exam: vital signs normal. U/S: hyperechoic line in stomach. Gastroscopy confirmed the dx. What is it?
Taenia asiatica
Gastric ulcer
Eosinophilic gastroenteritis
Foreign-body ingestion
You are correct. Gastroscopy revealed a parasitic nematode belonging to the genus Anisakis (a 2- to 3-cm-long roundworm) that was half embedded w/in the gastric mucosa. Part of the life cycle of Anisakis nematodes includes fish. When raw fish containing encysted nematodes is ingested, the parasite passes through the GI tract. Sometimes, however, the nematode penetrates the gastric mucosa, resulting in acute gastritis that manifests 1-12h after ingestion. The condition is called anisakiasis. Freezing fish before consumption can prevent it.

BMJ 2020;371:m3730