Fasciolopsis buski, the largest intestinal fluke of humans.
Immature eggs are
discharged into the intestine and stool
Eggs become embryonated in water
eggs release miracidia
which invade a suitable snail intermediate host
In the snail the parasites undergo several developmental stages (sporocysts
The cercariae are released from the snail
encyst as metacercariae on aquatic plants
The mammalian hosts become infected by ingesting metacercariae on the
aquatic plants. After ingestion, the metacercariae excyst in the
attach to the intestinal wall. There they develop into adult flukes (20
to 75 mm by 8 to 20 mm) in approximately 3 months, attached to the
intestinal wall of the mammalian hosts (humans and pigs)
The adults have a life span of about one year.
Asia and the
Indian subcontinent, especially in areas where humans raise pigs and
consume freshwater plants.
are light and asymptomatic. In heavier infections, symptoms include
diarrhea, abdominal pain, fever, ascites, anasarca and intestinal
identification of eggs, or more rarely of the adult flukes, in the stool
or vomitus is the basis of specific diagnosis. The eggs are
indistinguishable from those of Fasciola hepatica.
comparison with other intestinal parasites
the drug of choice.
* This drug is
approved by the FDA, but considered investigational for this purpose.