Merck Manual

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Chelsea Marie

, PhD, University of Virginia;

William A. Petri, Jr

, MD, PhD, University of Virginia School of Medicine

Reviewed/Revised Aug 2023
Topic Resources

Fasciolopsiasis is infection with the intestinal fluke Fasciolopsis buski, which is acquired by eating aquatic plants or ingesting contaminated water.

Flukes are parasitic flatworms that infect various parts of the body (blood vessels, gastrointestinal tract, lungs, liver) depending on the species.

F. buski is present in the intestine of pigs in many parts of Asia and the Indian subcontinent. The prevalence of infection is highest among children in endemic areas. F. buski is also called the giant intestinal fluke because it is largest fluke that infects humans.

Human infection is typically acquired by ingesting contaminated water or eating plants, particularly bamboo shoots, watercress, or water chestnuts, that bear infectious metacercariae. Adult worms attach to and ulcerate the mucosa of the proximal small bowel. They grow to about 20 to 75 mm by 8 to 20 mm. Adult worms have a life span of about 1 year.

Fasciolopsiasis is generally asymptomatic. In heavy infections, symptoms typically begin 30 to 60 days after exposure and can include anorexia, vomiting, diarrhea, abdominal pain, and signs of malabsorption. Peripheral eosinophilia may be present.

In severe cases, malabsorption can result in edema and ascites due to protein loss. Vitamin B12 deficiency and anemia can also occur.

Diagnosis of fasciolopsiasis is made by finding eggs or, less commonly, adult worms in the feces. The eggs are indistinguishable from those of Fasciola hepatica.

Treatment of fasciolopsiasis is with praziquantel 25 mg/kg orally 3 times a day for 1 day.

Prevention involves not drinking contaminated water or eating freshwater plants in areas where Fasciolopsis buski is endemic.

See also the Centers for Disease Control and Prevention (CDC) information on fasciolopsiasis.

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