The Epidemiology Transition (DP IB Geography)

Revision Note

The Disease Continuum

  • The Epidemiology Transition describes fluctuations in disease and morbidity

  • It directly links to the Nutrition Transition and Demographic Transition:

    • Dietary changes occur as countries become more developed

    • As a result, there are fluctuations in disease and morbidity 

  • As development improves and diets change:

    • Communicable (infectious) disease rates will go down 

    • Noncommunicable (non-infectious) disease rates will increase

  • At the beginning of the Epidemiology Transition:

    • Countries are less developed and mortality rates for communicable diseases are high

    • There are low rates of non-communicable disease

  • Towards the end of the Epidemiology Transition:

    • Development is higher and mortality rates for noncommunicable diseases increase

    • There are low rates of communicable disease

  • Where the lines intersect indicates a dual burden of disease:

    • Both communicable and non-communicable diseases exist

    • This burden affects some LICs and NEEs e.g. India

The Epidemiology Transition

Graph illustrating the epidemiologic transition, showing how mortality rates from communicable diseases (red line) decrease while non-communicable diseases (blue line) increase.
The Epidemiology Transition

The Disease Continuum

  • The Disease Continuum looks at diseases of poverty and diseases of affluence

  • Diseases of poverty are diseases located in poorer areas. This can be in LICs or areas within HICs:

    • Diseases of poverty include communicable diseases, parasites and deficiency diseases e.g. HIV/AIDS, malaria, kwashiorkor, tuberculosis and waterborne diseases like cholera

    • This is a result of poor education, poor sanitation access and hygiene, unsafe water, poor nutrition, and inadequate healthcare 

  • Diseases of affluence are diseases located in richer areas, typically in HICs:

    • This includes noncommunicable diseases, like heart disease, type 2 diabetes, obesity and some allergies and asthmas 

    • It can also include longevity-related illnesses like dementia (as life expectancy is longer) 

    • May also include mental health issues like stress and depression

    • This is a result of westernisation, overconsumption of diets and lifestyles and longer life expectancy 

    • Diseases of affluence are steadily making their way into poorer countries as they develop further

Examiner Tip

Make sure you know the difference between diseases of poverty and diseases of affluence. You might be asked to discuss the difference between the two. How can the disease continuum relate to the Epidemiological Transition? How can it all be tied in with the Nutrition Transition?

Implications of a Global Ageing Population

Implications of a global ageing population for disease burden

  • The disease burden is how much strain a health issue places on the population: 

    • The disease burden = morbidity + mortality

    • It is measured using Disability-Adjusted Life Years (DALYS)

    • Higher DALYS indicate a higher disease burden 

Burden of disease in 2019, per 100,000 people

World map showing Disability-Adjusted Life Years (DALYs) per 100,000 people by region, with a gradient scale from 10,000 to 100,000, darkest in central Africa.
Burden of disease in 2019, per 100,000 people
  • Life expectancy is rising, predominantly in HICs. However, it is also rising in LICs as they develop 

  • As life expectancy rises, more people reach old age

  • In many countries, birth rates are also decreasing: 

    • Rising life expectancy and decreasing birth rates leads to an ageing population 

  • In many countries with an ageing population, a large proportion of the population is older, e.g. Japan or Germany 

  • If there are more older people, there are more old-age-related diseases 

  • These include degenerative diseases like dementia or arthritis, as well as heart conditions and diabetes: 

    • This puts a strain on healthcare systems

    • There will be a greater demand for workers and infrastructure 

    • More resources go towards this sector of healthcare, leaving other sectors behind

    • This produces a disease burden as a result of ageing populations 

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