Fascioliasis is infection with the liver fluke Fasciola hepatica, which is acquired by eating contaminated watercress or other water plants.
Flukes are parasitic flatworms that infect various parts of the body (eg, blood vessels, gastrointestinal tract, lungs, liver) depending on the species.
F. hepatica is the sheep and cattle liver fluke. Incidental human fascioliasis, acquired by eating watercress contaminated by sheep or cattle dung, occurs in Europe, Africa, China, and South America but is rare in the US.
In acute infection, immature flukes migrate through the intestinal wall, the peritoneal cavity, the liver capsule, and the parenchyma of the liver before entering the biliary ducts where they mature to adulthood in about 3 to 4 months.
Symptoms and Signs of Fascioliasis
Acute infection can cause abdominal pain, hepatomegaly, nausea, vomiting, intermittent fever, urticaria, eosinophilia, malaise, and weight loss due to liver damage.
Heavy infection can cause sclerosing cholangitis and biliary cirrhosis. Ectopic lesions may occur in the intestinal wall, lungs, or other organs.
Pharyngeal fascioliasis that results in dysphagia has been reported after consumption of infected raw liver in the Middle East; this infection is called halzoun.
Diagnosis of Fascioliasis
- Antibody assays
- Microscopic examination of stool or duodenal or biliary material for eggs
CT frequently shows hypodense lesions in the liver during the acute stage of fascioliasis. Ultrasonography, CT, MRI, endoscopic retrograde cholangiopancreatography (ERCP), or cholangiography can detect biliary tract abnormalities in chronic disease.
Antibody detection assays are useful in
- The early stages of infection before eggs are produced
- Chronic infection when egg production is sporadic or low
Loss of detectable antibodies occurs 6 to 12 months after cure.
In chronic infections, eggs may be recovered from the stool or from duodenal or biliary materials. The eggs are indistinguishable from those of Fasciolopsis buski.
In endemic areas, eggs can also be seen in stool after ingestion of infected animal livers, resulting in a misdiagnosis of fascioliasis. Thus, patients should be asked to follow a liver-free diet for several days before their stool is examined.
Treatment of Fascioliasis
- Triclabendazole or possibly nitazoxanide
Treatment of fascioliasis for patients ≥ 6 years is with triclabendazole 10 mg/kg orally once with food. Nitazoxanide 500 mg orally twice a day for 7 days may be effective, but the data are limited.
Treatment failures are common with praziquantel; it is not recommended.
In some patients, extraction of adult flukes from the biliary tract by ERCP may be useful.
Prevention involves not eating watercress or other freshwater plants in regions where F. hepatica is endemic.
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