fh.2.3 The importance of diffusion in the spread of innovation and disease
Content
- Geographic inquiry and concept(s)
- How physical and human processes lead to changes in food production and consumption, and incidence and spread of disease.
- Geographic knowledge and understanding
- The importance of diffusion (including adoption/acquisition, expansion, relocation) in the spread of agricultural innovations, and also in the spread of diseases, and the role of geographic factors (including physical, economic and political barriers) in the rate of diffusion
- Case study or detailed examples
- Neither required by the syllabus
- Aims of this lesson
- To have knowledge and understanding of how agricultural innovations are spread via adoption, expansion or relocation.
- To have knowledge and understanding of how diseases are spread via adoption, expansion or relocation.
- To have an understanding of how the physical, economic and political barriers impact the rate and spread of diseases.
- To have an understanding of how the physical, economic and political barriers impact the rate and spread of agricultural innovation.
Base knowledge and understanding
News article
Spread of Ebola in DRC ‘outpacing’ response efforts, warns WHO
Director general of World Health Organization urges neighbouring countries to take immediate action
The Guardian · 25 May 2026
Key terms
- Contagious diffusion
- Infectious diseases are a prime example. A disease follows no rules, nor does it recognise borders as it spreads. A forest fire is another example that fits this category. A kind of expansion diffusion.
- Diffusion
- The spread of a phenomenon, such as an idea, a technological innovation, or a disease, over space and time.
- Diffusion of innovations
- The leading theory in agricultural extension post World War II until the 1970s. It is still used today in agricultural extension, particularly when extension is concerned with an adoption of a particular technology. It is proposed that five main elements influence the spread of a new idea: the innovation itself, adopters, communication channels, time, and a social system. The categories of adopters are innovators, early adopters, early majority, late majority, and laggards.
- Expansion diffusion
- When innovations spread to new places while staying strong in their original locations.
- Geographic factors
- Encompasses demographic, environmental, social, cultural, economic, and political elements that can influence or be influenced by the geography of an area.
- Hierarchical diffusion
- Follows a chain of command, something you see in business, government, and the military. The CEO of a company or the leader of a government body generally knows information before it is disseminated among a wider employee base or the general public. Fads and trends that start with one community before spreading to the wider public can also be hierarchical. A kind of expansion diffusion.
- Relocation diffusion
- Occurs when people move from their original location to another and bring their innovations (or disease) with them.
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Review
- Explain how the process of diffusion contributes to the spread of disease. [2]
- Outline one difference between expansion diffusion and relocation diffusion. [2]
- Explain two geographic factors that can act as barriers to the diffusion of agricultural innovations. [4]
- Examine the relative importance of physical and human barriers in limiting the diffusion of agricultural innovations. [10]
- Examine the role of diffusion processes in explaining the spread of one named vector-borne disease and one named water-borne disease. [10]