This book is a guide for planners and programme managers in the health and education sectors who are charged with implementing community-based programmes for control of soil-transmitted helminth and schistosome infections in school-age children. Schistosomiasis and soil-transmitted helminth cause more than 150 000 deaths each year. In school-age populations in developing countries, intestinal helminth infections rank first among the causes of all communicable and noncommunicable diseases. This book describes an approach to the control of infections that is based on the periodic treatment of school-age children – a particularly high-risk group. Parasitological surveys of school population samples, allied to treatment programmes, can then be used as a basis for selecting an appropriate control strategy for the whole community.