MSD Manual

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Life Cycle of Schistosoma

Life Cycle of Schistosoma

  • 1. In people, the schistosome eggs are passed in stool or urine into water.

  • 2. In water, the eggs hatch and release immature schistosome larvae (called miracidia).

  • 3. The miracidia swim and enter a snail.

  • 4–5. Within the snail, the miracidia develop into sporocysts and then into a form (called cercaria) that has a forked tail and can swim in water. The cercariae are released from the snail into the water and penetrate the skin of people who enter the water.

  • 6. When cercariae penetrate the skin, they lose their tail and become schistosomula. The schistosomula then travel to the liver, where they mature into adults.

  • 7. Male and female worms pair up and migrate to veins in the intestine or bladder (depending on their species). There, where they remain, and the females begin to lay eggs.

Life Cycle of Schistosoma