Fascioliasis is a rare foodborne parasitic animal infection that can be transmitted to humans that is usually caused by Fasciola hepatica (flatworms), also known as “common liver fluke," or the parasite, Fasciola gigantica. Individuals are infected by eating raw watercress or other water plants contaminated with the parasite larvae, after which the larvae mature and move through the intestines to the liver and bile ducts and produce eggs. The parasites can also migrate to other areas of the body. A subtype of fascioliasis, known as Halzoun syndrome, may affect the throat.

Fascioliasis has both early (acute) and late (chronic) phases. During the acute phase (two to four months) when the parasites migrate from the intestines to the liver, symptoms may include nausea and vomiting, gastrointestinal problems, extreme abdominal pain and/or tenderness, swollen liver, internal bleeding, fever, rash, hives, difficulty breathing, and bronchial asthma attacks. During the chronic phase when the parasites settle into the bile ducts, patients may experience similar symptoms of the acute phase, along with intermittent pain, intolerance to fatty food, itching, bile duct inflammation, blockage and inflammation of the gallbladder, gallstones, pancreas (pancreatitis), liver fibrosis, jaundice (yellowing of skin and eyes), and anemia.

Treatment for fascioliasis with the preferred drug, oral triclabendazole, should be administered promptly to prevent liver complications and usually provides a cure.