ABSTRACT
AND CHILDREN environment, as their immune systems require many years to develop. Before birth the foetus is protected, to a large extent, by its mother’s defences and the placenta. Resistance to infection thereafter depends on general body defence mechanisms, innate genetic inheritance and an acquired passive or active resistance from their ongoing exposure to the world around them. Internal and external stressors can reduce their resistance to disease; immunisation programmes (see Chapter 1) aim to boost their ability to remain healthy and thus allow them to develop to their optimum physical condition. Protection from micro-organisms is provided by a series of ‘barriers’.
