Water for farming in Senegal river valley, or the risk of water-borne disease in the Sahel

barrage conservation de l'eau dams enfermedades humanas environmental impact epidemia epidemics epidemie esquistosomosis human diseases impact sur l'environnement impacto ambiental maladie de l'homme manejo del suelo mauritania mauritanie mise en valeur du sol public health represas rio senegal sahel schistosomiasis schistosomose senegal senegal river soil management water conservation water management