Disease

• If we had a Morgan Freeman moment could they all be stopped today?

Do you agree?

• https://www.ted.com/talks/shereen_el_feki_how_to_fight_an_epidemic_of_bad_laws

Spread of diseaseSpread of disease

Objectives1.Explain how the geographic concepts of diffusion by relocation and by expansion apply to the spread of diseases2.Examine the application of the concept of barriers in attempts to limit the spread of diseases.3.Describe the factors that have enabled reduction in incidence of a disease

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

bacteria’

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

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

Complete the worksheet as we go through the next few slides

Complete the worksheet as we go through the next few slides

Disease diffusionDisease diffusion

Distance from source of disease

Inci

dence

of

dis

ease

X

•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.

Types of diffusionTypes of diffusion

1. Expansion diffusion – including contagious diffusion, hierarchical diffusion and network diffusion

2. Relocation diffusion3. Mixed diffusion

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).

Contagious diffusionContagious 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)

Hierarchical diffusionHierarchical 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

Network diffusionNetwork 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

Relocation diffusionRelocation 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

Mixed diffusionMixed 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.

+

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)

Barriers to stop the spread of disease?

1. Think of ways that stop the spread of diseases

2. For each way explain how it can and can’t contain the disease (if applicable)

3. Can these ‘barriers’ be categorised?

Use Encephalitis in India 2012 as an example

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

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

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?

• 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

The Pandemic Risk IndexThe Pandemic Risk Index

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

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

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

H1N1 – exam questionsStudy the 4 maps (fig 10.18) – p.276

IB Geography course companion1.Describe the diffusion of the H1N1

(swine flu) virus in 2009. (3 marks)2.Name the type of disease diffusion

indicated by the maps. Explain your answer. (5 marks)

http://maps.google.com/maps/ms?ie=UTF8&oe=UTF8&msa=0&msid=106484775090296685271.0004681a37b713f6b5950

Exam questionExam 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.450-454 of Planet Geography to help you answer this question.

Spread of diseaseSpread of disease

1. Explain how the geographic concepts of diffusion by relocation and by expansion apply to the spread of diseases

2. Examine the application of the concept of barriers in attempts to limit the spread of diseases.

3. Describe the factors that have enabled reduction in incidence of a disease

The Geography of Food and Health – part 3; diseaseThe Geography of Food and Health – part 3; disease

Describe the factors that have Describe the factors that have enabled reduction in incidence of enabled reduction in incidence of

a diseasea disease• Disease – Leprosy• Information – World Health Organisation

information sheet on leprosyMake 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

HomeworkRead the IB Geography course companion case studies for Geography of

Food and Health and answer the questions:1. What is a superbug?2. What is the link between agro-industrialisation and emerging/re-

emerging diseases? Give examples.3. Can you think of any different cultural norms that may increase the

likelihood of contracting disease?4. Can you think of any different cultural norms that may decrease the

likelihood of contracting disease?

Cholera in Haiti: 1. What kind of disease diffusion did Haiti experience?2. Why was cholera such a big problem in Haiti, given that it is a disease

that can be treated?3. What measures were taken to try to reduce the vulnerability of the

Haitian people?

Disease diffusion and barriers to diffusion

Tasks:1. Read p.447-449 of Planet Geography2. Briefly explain how leprosy is transmitted and explain what type of

disease diffusion you think it is. Justify your answer.3. What are the barriers to diffusion for leprosy? 4. What are the challenges in stopping/slowing the spread of

leprosy?5. Briefly explain how 1 water borne and 1 vector borne disease is

transmitted.6. What are the barriers to diffusion for your chosen water borne and

vector borne disease ? 7. What are the challenges in stopping/slowing the spread of your

chosen water borne and vector borne disease?8. Explain why the principle of ‘disease diffusion’ cannot be so easily

applied to water borne and vector borne diseases