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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
, rediae
, and
cercariae
). The
cercariae are released from the snail
and
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 duodenum
and 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.
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