Fasciolopsis buski

Fasciolopsis buski lives in the small intestine of humans and pigs.  Measuring up to 80 mm in length, it is one of the largest trematodes found in humans.  This parasite is found in many countries in the Orient and, as with many other parasites that infect humans, pigs serve as a reservoir host.

The life cycle of this parasite is similar to that of Fasciola hepatica.  The worms produce eggs (up to 25,000 eggs per worm per day) that are passed in the host's feces.  The first intermediate host is a snail, and the cercariae that emerge from the snail encyst on vegetation.  Humans are infected with then eat vegetation contaminated with metacercariae.  Click here to view a diagram of the life cycle.

Chronic infections with this parasite lead to inflammation, ulceration, hemorrhage, and abscesses of the small intestine, and these can ultimately lead to the host's death.  Diagnosis of the disease is based on recovering eggs in the host's feces.

Several books and a number of web sites state that this parasite either causes directly or is associated with an increased risk of cancer, HIV, or any number of other diseases in humans.  There is absolutely no evidence whatsoever that this parasite causes cancer, HIV, or any other disease in humans.

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Fasciolopsis buski egg. The egg is very similar to that of Fasciola hepatica; approximate size = 130 µm in length.

 

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Stained whole mount of a Fasciolopsis buski adult; approximate length = 50 mm.  (Click here to view a second, labeled image of this species).

 

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Another example of an adult Fasciolopsis buski.  This specimen is stained lighter and is much larger than the example above, and some organs are seen more easily.  (Original image from Taipei Medical College Parasitology web site, and modified for use.