Epidemiological Transition Model

• Epidemiological transition

  The changing patterns of population age distribution, mortality, fertility, life expectancy, and causes of death. The model assumes that infectious diseases are replaced by chronic diseases over time due to expanded public health and sanitisation.
• The Epidemiological Transition Model, developed by Abdel Omran in 1971, describes shifts in patterns of mortality and disease as societies progress.
• “A characteristic shift in the disease pattern of a population as mortality falls during the demographic transition: acute, infectious diseases are reduced, while chronic, degenerative diseases increase in prominence, causing a gradual shift in the age pattern of mortality from younger to older ages.” -- Abdel Omran 1971
• The first three stages were in Orman's original model from the 1970s. Public health researchers revisited and modified his theory in the 1980s, adding the fourth and fifth stages.
• What are the names of the 5 stages in the epidemiological transition model?

  • Stage 1: Age of pestilence and famine
  • Stage 2: Age of Receding Pandemics
  • Stage 3: Age of Degenerative and Man-Made Diseases
  • Stage 4: Age of Delayed Degenerative Diseases
  • Stage 5: Age of Re-Emerging Infectious Diseases
• What are the traits of: Stage 1: Age of Pestilence and Famine?

  1. Life expectancy is low, often around 20 – 40 years.
  2. High mortality rates due to infectious diseases, epidemics, and poor sanitation.
  3. Malnutrition and famine are common, as food production is subsistence-based and the economy is poor.
  4. Population growth is slow or stagnant due to high birth and death rates.
• Examples of Stage 1: Age of Pestilence and Famine include ->

  1. Pre-industrial societies, such as Mediaeval Europe during the Black Death.
  2. Modern examples may include remote tribal communities in parts of the Amazon or Papua New Guinea.
  3. Small pox: 12,000 Years of Terror, first appeared in agricultural settlements in north-eastern Africa around 10,000 B.C. Egyptian merchants spread it from Africa to India. In Europe, near the end of the eighteenth century, the disease accounted for nearly 400,000 deaths each year
• What are the traits of Stage 2: Age of Receding Pandemics?

  • Life expectancy increases significantly, often reaching 50 years or more.
  • Population grows rapidly due to high birth rates and declining death rates. The discovery of penicillin in 1928 led to widespread and dramatic declines in death rates from previously serious diseases.
  • Change in socio-economic conditions: Improved sanitation; better diet, advances in medicine; and development of healthcare
  • Causes of morbidity and mortality: Reduced number of infections; increases in occurrence of strokes and heart disease
• Stage 2 improvement occurred before many effective medical treatments and was due to the impact of the following interventions:

  1. Clean water
  2. Sanitary sewage
  3. Mosquito suppression (nets)
  4. Increased food safety
  5. Increased pre- and post-natal care
• Examples of Stage 2: Age of Receding Pandemics include?

  1. Industrialising countries in the 19th century (e.g., Britain during the Industrial Revolution).
  2. Some low-income countries today, such as parts of Sub-Saharan Africa.
• Traits of Stage 3: Age of Degenerative and Man-Made Diseases?

  • Mortality continues to decline and eventually approaches stability at a relatively low level. Due to advanced healthcare systems and vaccination reducing infectious diseases.
  • Non-communicable diseases (NCDs), such as heart disease, cancer, and diabetes, become the leading causes of death.
  • Lifestyle-related illnesses (e.g., smoking, poor diets, addiction, etc.) emerge. Due to changes in socio-economic conditions.
  • Life expectancy continues to rise, often surpassing 60-70 years.
• Examples of Stage 3: Age of Degenerative and Man-Made Diseases

  1. Early 20th century United States and Western Europe.
  2. Middle-income countries, such as India and Brazil.
• Traits of Stage 4: Age of Delayed Degenerative Diseases:

  1. Advanced medical technologies and health interventions delay the onset of chronic diseases.
  2. Mortality rates are low, and life expectancy increases to 70+ years.
  3. The focus shifts to improving quality of life and manageing ageing populations.
  4. Health issues from overnutrition (e.g., obesity) and mental health become significant.
• Examples of Stage 4: Age of Delayed Degenerative Diseases?

  • High-income countries, such as the United States, Japan, and much of Western Europe.
  • Urban areas in some rapidly developing nations.
• Traits of Stage 5: Age of Re-Emerging Infectious Diseases include:

  • Globalisation, antibiotic resistance, and environmental changes lead to the resurgence of infectious diseases.
  • Emerging diseases (e.g., COVID-19) and re-emerging diseases (e.g., tuberculosis) challenge public health systems.
  • Lifestyle-related and chronic diseases remain prevalent alongside infectious diseases.
  • Health disparities become more pronounced.
• Examples of Stage 5: Age of Re-Emerging Infectious Diseases?

  • Worldwide during the COVID-19 pandemic.
  • Developed countries experiencing antibiotic resistance (e.g., MRSA in the US and Europe).
• Fill in labels:

  A) Non-Communicable Diseases

  B) Communicable Diseases

  
• Evidence that supports the epidemiological transition model:

  • The graph shows the ET in the USA which shows the clear shift in the major causes of death between 1900 and 2010.
  • This shift in demographics and disease is caused by factors such as the use of antibiotics and increased public sanitation.
  • Some critics argue that the increase in chronic diseases may be an illusion resulting from more advanced medical technologies being able to diagnose diseases that previously remained undiagnosed.