Improving health is one of the main goals of water and environmental sanitation (WES) interventions. Despite this, many aid and development workers may have only a limited knowledge of the infections they try to prevent. Although the relevant information does exist, it is often scattered in specialised literature and rarely finds its way into the field. This manual addresses this problem by presenting information on these infections in relation to the interventions that fieldworkers typically control u i.e: water supply, sanitation, drainage, solid waste management, and vector control. It has been produced primarily for non-medical aid and development workers, but anyone working in WES, or in the prevention of infections related to WES, will find this book useful.