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Social Context
culture, religion, social system, human rights, labour market, education system
GLOBALISATION
income, education, gender, ethnicity, ageing
Environmental factors
living and working conditions, health-related behaviour
HEALTH SYSTEMS
Structural Influences
Biological processes
HEALTH QUALITY OF INDIVIDUALS
10.66 Influences on the quality of health.
Many diseases in LEDCs are spread through the process
of geographic diffusion. Earlier in this chapter the
Not all diseases spread through contagious diffusion.
Some diseases, such as AIDS, spread through hierarchical
diffusion. In hierarchical diffusion, there are channels of
diffusion among people or groups that are more susceptible to the disease, and the disease by-passes individuals
or groups that do not share this vulnerability.
concept of diffusion was introduced (in the section
headed ‘the changing nature of food production’). In that
section, it was noted that diffusion refers to the way in
which new ideas are spread. The concept of diffusion also
applies to the spread of most things across geographical
Expansion diffusion takes place in populations whose
space, including the spread of communicable diseases.
locations are stable and fixed. It is the disease that moves,
not the people. Relocation diffusion, on the other hand,
There are two broad types of diffusion, expansion diffuinvolves the movement of individual people who carry
sion and relocation diffusion (figure 10.67). In expansion the disease to new locations (figure 10.67). When expandiffusion, an innovation, an idea — or a disease —
sion diffusion occurs, the disease remains at the source
develops in a source area and spreads out from there
area, often becoming more intense. When relocation diffuwhile also remaining strong in its source area. This can
sion occurs, the disease evacuates the source area along
happen in two ways. With contagious diffusion, the
with the person who is the carrier.
disease spreads out in several directions from the source,
affecting most individuals who come into contact with it The diffusion of disease can be thought of very simply
(even if they do not show the symptoms).
as one person passing an infection to someone else, who
in turn passes it on to others, and so on. However, this
Contagious Diffusion
Hierarchical Diffusion
Expansion Diffusion
10.67 Types of diffusion.
Food and health
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Relocation Diffusion