The Epidemiology Transition (SL IB Geography)

• 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

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

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

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