Fasciolopsis buski

Fasciolopsis buski is a Trematode that causes the disease fasciolopsiasis. It is also called the giant intestinal fluke and is one of the largest parasites to infect humans.

Disease / Pathology

Fasciolopsis buski causes the disease fasciolopsiasis. Inflammation of the intestinal wall due to attachment will lead to the over secretion of mucous, ulceration and hemorrhage. This can lead to abscess formation on the intestinal wall. When the infections are heavy there is the possibility of bowel obstruction and acute ileus. The production of worm metabolites may lead to edema and or ascites to allergic reactions. Malabsorption can occur specifically of protein and vitamin B12.

Patients will many times present with an eosinophilia and leukocytosis. Light infections present with few symptoms. The heavier the infections are the more symptoms that may present. Abdominal pain, diarrhea,

Location in the Host

Fasciolopsis buski is located on the wall of the small intestine inhabiting the duodenum and jejunum. When infections are heavy the flukes can be found in the stomach and most of the intestinal tract.

Geographic Distribution

Fasciolopsis buski is found in the Far East (Thailand, India, China and Taiwan, Indonesia and Asia).

Life Cycle

The primary Fasciolopsis buski reservoir are swine. Places where swine farming occur will have higher incidences of Fasciolopsis buski infections. Dogs and rabbits also act as reservoirs.

The metacercariae on water plants are ingested by humans or pigs causing infections. Excystation occurs in the duodenum and undergo maturation in the small intestine where eggs are produced and passed in the stool. The unembroynated eggs undergo development in the water and have miracidia eventually hatch out to swim and penetrate the intermediate host snail. Eventually three molts occur within the snail to produce the free-swimming cercariae that eventually colonizes water plants (water chestnuts-bamboo shoots- water caltrop) and develop into metacercaiae (the definitive host infective form).

Morphology & Diagnosis

Fasciolopsis buski eggs are very similar to the eggs of Fasciola hepatica and are indistinguishable. They are large eggs having a length of 130-150u and width of 63-90u. The operculum is small and indistinct and can be made to “pop” open by gently tapping on a Lugol’s iodine prep containing the eggs.


Comparison of F. hepatica and F. buski eggs illustrating how similar they are in appearance