Public health is the science and art of promoting, protecting, and improving health and well-being through organised efforts of society (Department of Health 1988). This chapter provides an overview of how the determinants of health, and consequently disease profiles, have changed over time in terms of emphasis and influence, and what role public health has, and can play, sometimes with government intervention, to maximise the public's health given these changes.
Health and disease can be considered as two extremes of a continuum. However, since in general it has proved difficult to produce a definition of 'health' with measurable outcomes, biologists, anthropologists, health care professionals, and researchers have tended to focus on factors that indicate absence of health, illhealth, degrees of ill-health, or actual disease state. The classic definition of health is that proposed by the World Health Organisation in 1948: 'Health is a state of complete physical, mental and social well-being and not merely the absence of disease'. This definition, however, is not very helpful as not only does it describe an ideal state rarely attained in the real world, it also does not provide any clear measurable factors with which to assess if such a state has been achieved. The definition of Stokes et al. (1982) is a more helpful one as it acknowledges those aspects of health that can be measured: 'Health is a state characterised by anatomical integrity, ability to perform personally valued family, work and community roles; ability to deal with physical, biologic, and social stress; a feeling of well-being; and freedom from the risk of disease and ultimately death'. From this definition it can be inferred that disease compromises anatomical integrity, limits performance, can be physically or mentally impeding and possibly fatal, all factors with measurable outcomes. Being able to measure health or disease is important if health is seen as important among the objectives and values of most individuals, and such individuals expect governments and administrations to pursue policies that will give them the opportunity to live a healthy life of optimum duration and quality. Alternatively, or in addition, the governments and other administrations themselves regard attainment of health or maintenance of a healthy population as important, for whatever reason.