Trematode flatworms Fasciola hepatica and F. gigantica.
Consumption of watercress or other aquatic plants contaminated with infective metacercariae or contaminated pond water.
Broadly distributed. The highest rates of F. hepatica infection have been reported from Bolivia, Peru, Egypt, Iran, Portugal, and France. F. gigantica has a more limited distribution (parts of Africa, the Middle East, and South and East Asia).
The acute phase begins 6–12 weeks after infection and can last >4 months. Most patients are asymptomatic, but symptoms might include marked eosinophilia, abdominal pain, intermittent high fever, weight loss, or urticaria. Within weeks to months, symptoms of the acute phase subside as worms enter the bile ducts, beginning the chronic phase. Patients in this phase may also be asymptomatic or may present with biliary colic, epigastric pain, nausea, jaundice, or pruritus. The long-term prognosis depends on the extent of the liver and biliary damage.
Detection of eggs in stool or duodenal or biliary aspirates. Serologic tests may be useful during the acute phase, since egg production does not start until 3–4 months after exposure. Radiologic examinations, including ultrasonogram and CT of the liver, are helpful, especially during the hepatic or migratory acute phase.
First-line treatment is with triclabendazole, which is not commercially available for human use in the United States. An alternative drug is nitazoxanide. Surgical resection or endoscopic retrograde cholangiopancreatographic removal of adult flukes can be done in cases with biliary tract obstruction.
Avoid eating uncooked aquatic plants, including watercress, mint, and parsley; avoid drinking untreated freshwater.
Mas-Coma S, Bargues MD, Valero MA. Fascioliasis and other plant-borne trematode zoonoses. Int J Parasitol. 2005 Oct;35(11–12):1255–78.
Rowan SE, Levi ME, Youngwerth JM, Brauer B, Everson GT, Johnson SC. The variable presentations and broadening geographic distribution of hepatic fascioliasis. Clin Gastroenterol Hepatol. 2012 Jun;10(6):598–602.