Schistosomiasis, or bilharzia, is a parasitic disease caused by trematode flatworms of the genus Schistosoma. Larval forms of the parasites, which are released by freshwater snails, penetrate the skin of people in the water.In the body, the larvae develop into adult schistosomes, which live in the blood vessels.
The females release eggs, some of which are passed out of the body in the urine or faeces. Others are trapped in body tissues, causing an immune reaction. Signs and symptoms may include abdominal pain, diarrhea, bloody stool, or blood in the urine. In those who have been infected a long time, liver damage, kidney failure, infertility, or bladder cancer may occur. In children, it may cause poor growth and learning difficulty.
Safe and effective medication (praziquantal)is available for treatment of both urinary and intestinal schistosomiasis. Of the 78 countries considered endemic for schistosomiasis, only 52 countries have populations requiring preventive chemotherapy. The total number of people in need of preventive chemotherapy globally for 2014 was 258.9 million, of which 123.3 million were school-age children.