Opisthorchis viverrini infection
Eggs are initially ingested by snails. These eggs hatch, and freshwater fish are infected with the cercariae. In fish, the cercariae encyst. Humans become infected after ingesting raw, undercooked, salted, pickled, or smoked freshwater fish that contains these larval parasites. Adult worms in humans live in the bile and pancreatic ducts.
The majority of patients are asymptomatic, but some patients may develop fever and abdominal pain 2-4 weeks after acute exposure. Skin findings including urticaria are rarely found. Laboratory evaluation may reveal peripheral eosinophilia. Patients who suffer with chronic infection may present with abdominal pain and weight loss. Obstruction of the bile ducts may lead to cholangitis or liver abscess.
Diagnosis is made by identifying eggs in the stool. Adult worms may be seen during endoscopic retrograde cholangiopancreatography (ERCP) or occasionally during ultrasound of the gallbladder. Treatment is with praziquantel or albendazole.
This infection has been associated with cholangiocarcinoma in the endemic region.
B66.0 – Opisthorchiasis
90281006 – Infection by Opisthorchis viverrini
Differential Diagnosis & Pitfalls
- Other liver fluke infection (Clonorchis sinensis or Fasciola gigantica) – also endemic in Southeast Asia
- Infection with an intestinal fluke (including Haplorchis taichui and Echinostoma species)
- Ascariasis (can cause biliary obstruction)
- Primary sclerosing cholangitis