Schistosomiasis, also known as bilharzia, is a disease caused by parasitic worms. There are two forms of the disease, namely intestinal schistosomiasis caused by Schistosoma mansoni and S. japonicum, and urinary schistosomiasis caused by S. haematobium. Less commonly, S. mekongi and S. intercalatum also cause disease in humans. Infection with Schistosomes may present as an acute infection or as a chronic disease. Schistosomiasis ranks second to malaria as the most common parasitic disease in Africa.