1.A - how do diseases spread to new areas?

Question 1

how do diseases spread?

Answer 1

• migration and travel (time space compression, ACs/urban areas more affected)
• poor living conditions/crowding
• lack of education
• climate
• proximity to outbreak
• animals

Question 2

what seems to stop disease spreading?

Answer 2

• oceans/physical barriers
• lockdowns/quarantines
• vaccines
• altitude/low temperatures

Question 3

what facilitates disease spreading?

Answer 3

• animals/vectors
• direct transmission - sneezing/bodily fluids
• water/stagnant water
• temperature/climate change

Question 4

what model is used to show the spread of disease?

Answer 4

Hagerstrand model

Question 5

what shape is the Hagerstrand model and why?

Answer 5

• S shaped curve
• the number of people infected by an epidemic approximates an S shaped or logistic curve over time
• after a slow beginning, the number infected accelerates rapidly until eventually levelling out, as most of the susceptible population have been infected

Question 6

how does the Hagerstrand model graph change between different countries and why?

Answer 6

• the progress and diffusion of a disease may be interrupted by physical barriers

Question 7

what are the 4 stages of the hagerstrand model?

Answer 7

1. PRIMARY STAGE - outbreak is slow as it spreads from one fixed point. typically lasts for months. eventually disease reaches enough people and spreads exponentially
2. EXPANSION STAGE - rapid growth occurs due to contagious diffusion of populations. rate of infection rapidly increases, accelerated by travel, poor education, sanitation etc.
3. CONDENSATION STAGE - disease spread slows as populations become immune/already infected/barriers to diffusion take over. we become educated/vaccination/quarantined
4. SATURATION STAGE - disease spread stops. no new cases. everyones got it or everyones vaccinated.

Question 8

what is stage one of the Hagerstrand model?

Answer 8

PRIMARY STAGE - outbreak is slow as it spreads from one fixed point. typically lasts for months. eventually disease reaches enough people and spreads exponentially

Question 9

what is stage two of the Hagerstrand model?

Answer 9

EXPANSION STAGE - rapid growth occurs due to contagious diffusion of populations. rate of infection rapidly increases, accelerated by travel, poor education, sanitation etc.

Question 10

what is stage three of the Hagerstrand model?

Answer 10

CONDENSATION STAGE - disease spread slows as populations become immune/already infected/barriers to diffusion take over. we become educated/vaccination/quarantined

Question 11

what is stage four of the Hagerstrand model?

Answer 11

SATURATION STAGE - disease spread stops. no new cases. everyones got it or everyones vaccinated.

Question 12

what is the neighbourhood effect?

Answer 12

• people living in proximity to carriers have a greater probability of contracting a disease than those located further away
• close proximity to outbreak = ↑ likelihood of contracting disease = contagious diffusion

Question 13

what human factors could affect Hagerstrand’s model of how disease spread?

Answer 13

• population growth
• urbanisation brings with it the problems of housing, sanitation, pollution etc.
• migration/travel
• hunting and pasture practices

Question 14

how does a disease reach the “saturation” phase?

Answer 14

• the number infected eventually levels off as most of the susceptible population have been infected

Question 15

what are the 4 main types of disease diffusion?

Answer 15

1. expansion diffusion
2. relocation diffusion
3. hierarchial diffusion
4. contagious diffusion

Question 16

what is expansion diffusion?

Answer 16

• a disease has a source and spreads outwards into new areas
• meanwhile, carriers in the source area remain infected
• outbreak of TB is an example of expansion diffusion
• no transport/barriers involved

Question 17

what is relocation diffusion?

Answer 17

• occurs when a disease leaves the area of origin and moves into new areas
• the cholera epidemic in Haiti in 2010, which killed 7000 people, illustrates this process
• the disease, which originated in Nepal, was brought to Haiti by international air workers flown in to tackle the earthquake disaster of that year

Question 18

what is hierarchial diffusion?

Answer 18

• a disease spreads through an ordered sequence of places, usually from the largest more isolated centres
• diffusion is also channelled along road, rail and air transport networks which facilitate contact between carriers and a susceptible population
• in 2009 the H1N1 flu virus became a pandemic via international flight routes and airports

Question 19

what is contagious diffusion?

Answer 19

fast expansion

Question 20

what is network diffusion?

Answer 20

• network diffusion occurs when a disease spreads via transportation and social networks.

Question 21

what are the key barriers to diffusion?

Answer 21

1. mass vaccination
2. PHYSICAL BARRIERS:
   - distance
   - mountain ranges, seas, oceans, deserts and climate (e.g. malaria/flu season)
3. education policies e.g. lockdown
4. political borders (control flows of people - NE/AU in COVID)
5. distance from source - isolation

Question 22

what helps the rate of diffusion?

Answer 22

• proximity
• crowded areas/city
• going out if infected
• not having a vaccine

Question 23

how is HIV diffused?

Answer 23

POVERTY
- lack of education
- traditional belief systems/taboos
- lack of access to ATVs
- poor nutrition, sanitation, water shortage
- prostitution
- marginalised women/dominance of males over females