Schistosome parasite egg. Light micrograph of liver tissue with an egg (schistosome, centre) of the Schistosoma mansoni parasite. This parasitic trematode worm causes schistosomiasis or bilharzia in humans. Adult worms live in pairs in the blood stream surrounding the digestive tract. Hepatic schistosomiasis occurs when eggs cross from blood vessels into the liver and become trapped, forming granulomas. The most severe cases produce hepatomegaly or fibrosis of the liver. A female Schistosoma worm can produce 300 eggs per day. Magnification: x50 at 35mm size.