Understanding the Life Cycle of Schistosoma: How Cercariae Transform and Infect Human Hosts through Contaminated Freshwater

What is the Infective stage of the following parasite? Schistosoma japonicumSchistosoma haematobiumSchistosoma mansoni

Cercaria

The infective stage of all three Schistosoma species is a free-swimming larval stage known as cercariae.

Schistosoma japonicum: The cercariae of S. japonicum penetrate the host’s skin when in contact with contaminated freshwater, typically rice fields, lakes, and streams, and these cercariae transform into schistosomulae, which migrate via the host’s bloodstream to reach the hepatic portal system of the liver. In the liver, the worms mature into adult male or female worms and begin laying eggs.

Schistosoma haematobium: The cercariae of S. haematobium penetrate the host’s skin when in contact with contaminated freshwater, typically rivers and streams. After penetration, they transform into schistosomulae, which migrate to the venous plexuses around the bladder and ureters. In these tissues, they mature into adult male or female worms and begin laying eggs, which are excreted in the urine.

Schistosoma mansoni: The cercariae of S. mansoni penetrate the host’s skin when in contact with contaminated freshwater, typically ponds and swamps. After penetration, they transform into schistosomulae, which migrate to the hepatic portal system of the liver. In the liver, they mature into adult male or female worms and begin laying eggs.

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