Schistosomiasis, or bilharziasis, parasitic disease caused by the schistosome, a type of flatworm. The disease is usually acquired by bathing in infected water. The schistosome larvae enter the body through the skin and live in the blood as parasites. As adults they lay eggs that cause infection and destroy the kidneys, liver, and other organs. The disease can ultimately cause death. It afflicts more than 200 million people in Africa, Asia, and Latin America.