ABSTRACT
This chapter attempts to bring together the major determinants of population health in two related conceptual models, one highlighting the multi-level nature of determinants, the other their stage in the disease or disability process. The specific model espoused by health policy-makers and planners is also important, determining the type of health policies and programmes pursued. Two key appreciations are essential to understanding population health: first, the production of good and bad health involves many factors; and second, the complex relationships between factors. The agent—host—environment model was originally developed to explain infectious disease causation, with the agent component referring to infectious micro-organisms. The chapter presents three levels of prevention — primary, secondary and tertiary — that are generally recognized by public health specialists and epidemiologists. Primary prevention refers to measures taken to stop a disease (or injury) from occurring. These focus on upstream and midstream determinants of health.
