Schistosomiasis is caused by infection with Schistosoma blood flukes. It is estimated that 240-450 million people are currently infected, with over 800 million people at risk, especially in less developed countries. The life cycle of Schistosoma involves eggs released from infected humans and passing through water where they infect freshwater snails. Larvae emerge and can infect humans by penetrating the skin. In humans, the larvae mature into adult worms that reside in blood vessels and release eggs, causing tissue damage and pathology. Chronic infection can lead to liver and organ damage over time. Treatment involves praziquantel but control relies on improved sanitation and snail control.