Nematodes | Anisakis simplex | Raw or undercooked fish or squid | Acute (1–2 h after ingestion, maybe up to 14 d): sudden, severe, episodic epigastric distress, sometimes nausea and vomiting Chronic: diarrhea, urticaria, occasional coughing up of larvae, intestinal pseudo-obstruction | Ultrasound: might show small-bowel dilatation; thread-like gastric filling defects | Spontaneous recovery; occasional endoscopic removal of worms |
Trematodes (liver flukes) | Clonorchis sinensis | Korea, China, Taiwan, Vietnam, and Japan; raw or undercooked fish | Acute (within 1 wk of ingestion): fever, chills, tender hepatomegaly Chronic: asymptomatic; occasional cholangitis or pancreatitis | Stool for ova | Praziquantel |
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Echinostoma | Southeast and east Asia; raw or undercooked fish | Gastroenteritis, anemia, headaches, dizziness, stomach pain, diarrhea, anorexia, eosinophilia | Stool for ova | Mebendazole, albendazole, or praziquantel |
Trematodes (intestinal flukes) | Metorchis conjunctus | Raw white sucker fish (case report in Quebec)1 | 1–15 d incubation; abdominal pain, fever, diarrhea, headache, nausea | Stool for ova or serology | Praziquantel or spontaneous resolution |
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Heterophyes spp | Middle East, Asia; raw, marinated, or undercooked fish | Abdominal pain, diarrhea | Stool for ova | Praziquantel |
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Metagonimus spp | Middle East, Asia; raw, marinated, or undercooked fish | Abdominal pain, diarrhea | Stool for ova | Praziquantel |
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Nanophyetus salmincola | North America; raw, undercooked, or smoked fish | Diarrhea, abdominal pain, nausea and vomiting, fatigue, weight loss | Stool for ova | Spontaneous resolution or antiparasitic agents |
Cestodes | Diphyllobothrium latum | Raw, undercooked, or marinated fish | Abdominal pain, diarrhea, eosinophilia, occasional B12 deficiency | Stool for ova or passage of proglottids | Praziquantel or niclosamide* |
Protozoa | Giardia lamblia | North America; home-canned salmon; China, koi pla (ie, fish soup), using uncooked freshwater fish | Nausea, chills, fever, epigastric pain, foul-smelling diarrhea (might be mucous-mixed, bloody) | Trophozoites or cysts in stool | Metronidazole |