Parasitic trematode flatworm Schistosoma causes schistosomiasis. Freshwater snails act as an intermediate host and release the larval form of the parasite that penetrates the skin of people exposed to contaminated water. Worms mature and reproduce in the blood vessels, liver, kidneys, and intestines, releasing eggs, which become trapped in tissues triggering an immune response; may manifest as an either urinary or intestinal disease resulting in decreased work or learning capacity; mortality, while generally low, may occur in advanced cases usually due to bladder cancer; endemic in 74 developing countries with 80% of infected people living in sub-Saharan Africa; humans act as the reservoir for this parasite. Other water contact diseases are Leptospirosis, Schistosomiasis.