1. The free-swimming larval stage of certain parasitic flatworms (trematodes) that infects a snail host as the first step in its life cycle.
Usage: biology; parasitology; technical

Examples

• The miracidium emerges from the egg and must locate a suitable snail host within a few hours.
• Under the microscope, the miracidium displays characteristic ciliated cells that aid in its movement through water.
• Miracidia of Schistosoma species are responsible for initiating infection in freshwater snails.
• The miracidium penetrates the snail's tissue and develops into a sporocyst.
• In tropical regions, miracidia in contaminated water pose a significant public health risk.