Final answer:
The stage of Schistosoma that is released by infected snails is the cercaria. These larvae penetrate the skin of humans and are a critical part of the parasite's life cycle, contributing to the spread of schistosomiasis.
Step-by-step explanation:
The stage of Schistosoma that is released by infected snails is the cercaria. These are the free-swimming larvae responsible for penetrating the skin of humans, leading to schistosomiasis.
The complex life cycle of Schistosoma begins when infected humans excrete eggs in their urine or feces, which can contaminate fresh water systems. If these eggs reach water containing specific snail species, they hatch into miracidia, which infect the snails. Inside the snail, miracidia develop into cercariae, which are then released back into the water. The cercariae are particularly adapted to finding and penetrating human skin when contact is made with contaminated water. Once inside a human host, they continue their journey through the bloodstream, maturing into adult worms, mating, and producing eggs, thus sustaining the cycle of infection.
This parasitic disease is prevalent in tropical regions and poses significant health risks, including organ damage and chronic symptoms. Knowledge about the life cycle stages of Schistosoma, especially the cercarial stage, is crucial for understanding transmission and developing prevention strategies to combat schistosomiasis.