Successful control of schistosomiasis and the changing epidemiology of bladder cancer in Egypt.

Schistosomiasis is a parasitic disease caused by flatworms that live in snail-infested fresh water. It is endemic to 74 countries and affects some 200 million people worldwide, causing an estimated 200,000 deaths annually [1]. Schistosomiasis can affect the gastrointestinal tract and liver (S. mansoni and S. japonicum species), resulting in diarrhoeal disease and hepatic fibrosis, or the urinary tract (S. haematobium) where it causes haematuria, strictures, obstruction, super-infection and, ultimately, cancer. In children and vulnerable adults, systemic effects such as anaemia, malnutrition, stunted growth and impaired cognition can be profound. The association between this parasitic infestation and the development of bladder cancer literally took millennia to uncover. It is unusual for a parasitic disease to result in a fatal neoplastic process, and rarer still to have public health efforts, aimed at eradication of the parasitic menace, to result in a dramatic shift in the epidemiology of the most common cancer in a nation.