Epidemiology, one of the key disciplines in public health, is concerned with describing the patterns of diseases, identifying their causes and evaluating the effectiveness of health care and public health interventions. Such information helps to promote health and treat disease. This book introduces the key elements of epidemiological methods. The book examines: Concepts and applications of epidemiology Population measures of health and disease Descriptive and analytical study designs Intervention studies Risk assessment and preventive strategies Surveillance and screening