Opisthorchiasis is infection with 1 of 2 species of the liver fluke Opisthorchis, which is acquired by eating infected raw or undercooked fish.
Opisthorchiasis occurs in cats and dogs in eastern and central Europe, Siberia, and parts of Asia, such as Thailand and Cambodia. The life cycle of Opisthorchis requires both snails and fish. Human disease resembles clonorchiasis and is acquired by eating raw or undercooked freshwater fish that contains infectious metacercariae (encysted stage). After ingestion, metacercariae excyst and ascend through the ampulla of Vater into the biliary ducts, where they attach to the mucosa and mature. Adult flukes grow to 5 to 10 mm by 1 to 2 mm (O. viverrini) or 7 to 12 mm by 2 to 3 mm (O. felineus).
Symptoms include vague GI discomfort or bowel symptoms (diarrhea or constipation). Rarely, infection causes cholangitis or cholangiocarcinoma.
Diagnosis is by finding eggs in the feces.
Praziquantel 25 mg/kg po tid for 2 days is the treatment of choice.
Last full review/revision December 2009 by Richard D. Pearson, MD
Content last modified February 2012