Parasitic infections acquired by ingesting raw fish
| CATEGORY | GENUS, SPECIES | SOURCES | SYMPTOMS | DIAGNOSIS | TREATMENT |
|---|---|---|---|---|---|
| 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 |
| 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 |
| Heterophyes spp | Middle East, Asia; raw, marinated, or undercooked fish | Abdominal pain, diarrhea | Stool for ova | Praziquantel | |
| Metagonimus spp | Middle East, Asia; raw, marinated, or undercooked fish | Abdominal pain, diarrhea | Stool for ova | Praziquantel | |
| 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 |
↵* Praziquantel is indicated in Canada for the treatment of Schistosoma and some liver flukes, but not specifically for fish tapeworm. It is recognized as a treatment for Diphyllobothrium spp elsewhere, as is niclosamide. Niclosamide is not available in Canada.
Data from Butt et al,1 van Voorthuis and Weller,2 and Eastburn et al.3