1. Disease
If we had a Morgan Freeman moment could they all be stopped today?

2. Do you agree?

3. Spread of disease Objectives
Explain how the geographic concepts of diffusion by relocation and by expansion apply to the spread of diseases
Examine the application of the concept of barriers in attempts to limit the spread of diseases.
Describe the factors that have enabled reduction in incidence of a disease

4. ‘The greatest threat to our species is not global warming, warfare or poverty – the greatest threat is drug-resistant bacteria’

5. MEDCs at greatest risk from certain diseases.. Don’t make that mistake!
People in MEDCs have compromised immune systems because of over-use of certain antibiotics both in the community and the food chain

6. How are diseases spread?
Crowded working and living conditions
Inadequate sanitation
Unclean water supplies
Inadequate nutrition
Inadequate income  no medical help, no resources (e.g. soap/household cleaners, mosquito nets/repellent, antiseptic creams etc)
Long working hours
Inaccessible health care
Exposure to health risks at work as legislation not enforced
Inadequate education e.g. AIDS sufferers not understanding the concept of safe sex

7. Complete the worksheet as we go through the next few slides

8. Disease diffusion
The spread of disease into new locations – when incidences of diseases spread out from an initial source.
The frictional effect of distance (i.e. distance decay)  areas closer to the source are more likely to be affected by it; those further away less likely to be affected but might get affected at a later date.
Incidence of disease X
Distance from source of disease

9. Types of diffusion
Expansion diffusion – including contagious diffusion, hierarchical diffusion and network diffusion
Relocation diffusion
Mixed diffusion

10. Expansion diffusion
Occurs when the expanding disease has a source and diffuses outwards into new areas (it is the disease that moves not the people - therefore the disease remains at the source and often becomes more intense).

11. Contagious diffusion
The spread of an infectious disease, through the direct contact of individuals with those infected.
Disease spreads out in several directions from source affecting most individuals who come into contact (even if do not show symptoms)

12. Hierarchical diffusion
Occurs when a phenomenon spreads through an ordered sequence of classes or places, e.g. city  large urban area  small urban area. Or, within socially structured populations, innovations may be adopted first on the upper level of the social hierarchy and then trickle down to the lower levels.
Channels of diffusion among people or groups that are more susceptible to the disease - disease by passes individuals or groups that do not share this vulnerability

13. Network diffusion
Occurs when a disease spreads via transportation and social networks
E.g. the spread of HIV in Southern Africa along transport routes, or the spread of chicken pox in schools/playgroups

14. Relocation diffusion
When the spreading disease moves into new areas, leaving behind its origin or source of the disease e.g. a person infected with HIV moving into a new location

15. Mixed diffusion
A combination of contagious diffusion and hierarchical diffusion. AIDS is a prominent example in modern day society of a mixed diffusion disease, often spreading along the hierarchal, network, and contagious diffusion patterns. +

16. Disease diffusion is over simplified
Diffusion disease looks like it goes from one person to another. This is only true in DIRECTLY TRANSMITTED DISEASES
Water borne and vector borne diseases are slightly different (we will come back to this later)

17. Barriers to stop the spread of disease?
Think of ways that stop the spread of diseases
For each way explain how it can and can’t contain the disease (if applicable)
Can these ‘barriers’ be categorised?
Use Encephalitis in India 2012 as an example

18. Barriers to stop the spread of disease?
Natural?
Mountains
Water bodies – increase
Water bodies – decrease
Human?
Political boundaries
Economic boundaries
Social boundaries
Forced boundary – imprisonment, quarantine

19. Factors that have hindered reduction in incidence of disease.. India?
Social stigma e.g. AIDs ‘gay disease’
Social stigma e.g. leprosy due to deformaties
Education e.g. AIDs and denial in Sub-Saharan Africa
Multiple use of water source e.g. washing, cooking, sewerage, garbage  diarrhoea
Over use of pesticides  resistance and build up in food chain e.g. DDT
Medication side affects e.g. Malaria and liver failure
Cost e.g. TB vaccinations
Food source e.g. stagnant water in rice padi fields
Globalisation
Increased air travel
Risk of disease due to change in culture
PANDEMIC VIDEO

20. The Pandemic Risk Index
Pandemic disease: a disease epidemic over a wide geographic area and affecting a large proportion of the population, e.g. pandemic influenza (H1N1)
Tasks:
Read the worksheet about the PRI
Do you think areas of a high risk pandemic are more likely to be found in an HIC or an LIC? Why?

21. The Pandemic Risk Index
Question: Do you think areas of a high risk pandemic are more likely to be found in an HIC or an LIC? Why?
Answer: equally likely in both but for different reasons
LICs – usually, disease spreads easily and is hard to contain, owing to poor medical services and infrastructure.
HICs – quite often there are large movements of people through international air travel (more globally connected) and therefore a focus for disease transmission

22. Mexico – the source area for the H1N1 pandemic (2009 – 2010)

23. H1N1 was first reported in April 2009 – 9 countries; 148 cases, 8 deaths

24. One month later – May 2009 – 48 countries; 13,398 cases, 95 deaths

25. H1N1 – exam questions
Study the 4 maps (fig 10.18) – p.276 IB Geography course companion
Describe the diffusion of the H1N1 (swine flu) virus in (3 marks)
Name the type of disease diffusion indicated by the maps. Explain your answer. (5 marks)

27. Exam question
It is claimed that “the barriers to diffusion are more difficult to identify and define for diseases of affluence than they are for diseases of poverty”. Critically evaluate this statement. (10 marks)
Use p of Planet Geography to help you answer this question.

28. The Geography of Food and Health – part 3; disease
Spread of disease
Explain how the geographic concepts of diffusion by relocation and by expansion apply to the spread of diseases
Examine the application of the concept of barriers in attempts to limit the spread of diseases.
Describe the factors that have enabled reduction in incidence of a disease

29. Describe the factors that have enabled reduction in incidence of a disease
Disease – Leprosy
Information – World Health Organisation information sheet on leprosy
Make notes to answer the above question under the following subheadings:
What is leprosy?
How is it transmitted?
What has been done to try to reduce the incidence of leprosy?
How effective have these attempts been? Give incidence of leprosy stats for before/after

30. Homework
Read the IB Geography course companion case studies for Geography of Food and Health and answer the questions:
What is a superbug?
What is the link between agro-industrialisation and emerging/re-emerging diseases? Give examples.
Can you think of any different cultural norms that may increase the likelihood of contracting disease?
Can you think of any different cultural norms that may decrease the likelihood of contracting disease?
Cholera in Haiti:
What kind of disease diffusion did Haiti experience?
Why was cholera such a big problem in Haiti, given that it is a disease that can be treated?
What measures were taken to try to reduce the vulnerability of the Haitian people?

31. Disease diffusion and barriers to diffusion
Tasks:
Read p of Planet Geography
Briefly explain how leprosy is transmitted and explain what type of disease diffusion you think it is. Justify your answer.
What are the barriers to diffusion for leprosy?
What are the challenges in stopping/slowing the spread of leprosy?
Briefly explain how 1 water borne and 1 vector borne disease is transmitted.
What are the barriers to diffusion for your chosen water borne and vector borne disease ?
What are the challenges in stopping/slowing the spread of your chosen water borne and vector borne disease?
Explain why the principle of ‘disease diffusion’ cannot be so easily applied to water borne and vector borne diseases