Introduction

During the twentieth century there have been the greatest gains in health in most parts of the world owing to dramatic reductions in infant mortality, eradication of life-threatening diseases such as smallpox, and considerable improvements in life expectancy in developing and industrialised countries. In the past, life for most people was coarse, lacking in adequate nutrition, with poor housing and, above all, short in years. With the advent of improved sanitation and better living conditions, together with the availability of vaccinations and antibiotics, there has been, for many, a vast improvement in health status. However, health status still differs widely among nations and by geographic region. For instance, life expectancy is less than 50 years in some sub-Saharan African countries, but over 75 years in established industrialised countries. The wealthiest economies appear to be the healthiest. A crucial factor related to life expectancy is access to safe water! In much of the developing world, simply drinking water is a high-risk exposure.

Undoubtedly, the real gains in health over the last century can be attributed mainly to the impact of public health and disease prevention rather than to medical interventions. Public health can be primarily distinguished from clinical medicine by placing emphasis on the prevention of disease rather than the curing, and having a main focus on population and communities rather than on the individual patient.