Barrett et al. 1998

Introduction

• Emerging infectious diseases: seen as a big problem currently
• Emerging infections: are not a recent phenomenon but have always played a major role throughout human history
• 3 epidemiologic transitions
• Importance of anthropology for research

An Overview of Epidemiological Transitions

• Omran’s model criticisms
  • Implies each stage of the transition is more advanced and desirable than the previous stages
  • Using whole nations as units of analysis: buries the differential experience according to race, gender, and class
  • Restricted to a particular set of historical circumstances in the recent shift

Epidemiological Transitions: From the Late Paleolithic Age to the Industrial Revolution

Paleolithic Age Baseline

• Populations were too small and dispersed to support communicable pathogens
• Pinworm
• Ectoparasites
• Enteric pathogens
• Rate of emergence of diseases: may have increased as tool use allowed exploitation of novel ecological niches and as migration increased

The First Epidemiologic Transition

• Sedentism: led to larger groups + more interaction between people
• Increase in infectious disease mortality
• Accumulation of human waste
• Appearance of domesticated animals: provided a reservoir for zoonoses
• Agricultural practices
• Nutrient deficiencies
• Groups that most suffered: women, children, lower classes
• Increased severity of diseases
• Crowding in urban centers
• Epidemic outbreaks
• Increasing migration + trade: transmission of diseases
• Exploration + conquest: infections of Native Americans leading to pandemics

The Second Epidemiologic Transition

• Industrial Revolution
• Decline in infectious disease mortality within developed countries
  • Landmark for modernization
• Nutritional factors
• Extension of life expectancy: increased morbidity from chronic diseases
  • Cancer, diabetes, etc.
• Increasing of water + air pollution
• Differences in mortality based on social inequalities
• Improvements in child survival and life expectancy at birth in less developed nations
  • Immunizations + antibiotics

The Third Epidemiologic Transition

• Emerging infectious diseases
• New diseases: contribute to adult mortality
• Increased incidence and prevalence of pre-existing infectious diseases that were thought to be under control
• Generation of antimicrobial-resistant strains at a faster rate than safe new drugs is developed

Recently Emerging Infections

• 29 newly emerged pathogens since 1973
  • May be due to increases in detection rates
• Examples: HIV, Ebola, Marburg, Lyme disease, dengue fever, malaria, tuberculosis
  • Earlier transmission of HIV to urban Haiti: by more affluent Westerns engaging in sex tourism
• These new outbreaks are linked to climatic fluctuations and ecological disruptions
• Re-emerging infections causes: warmer climates, climatic fluctuations, poorly developed urban environments, increase in mosquito populations, decreases public health expenditures, poverty,
• Inevitability of genetic adaptations of microorganisms to the selective conditions posed by human technology and behaviors
• Host susceptibility and comorbidity
• Overuse of antibiotics in industrial animal: causes the rise of multi-drug resistant strains of food-borne pathogens
• Human populations are converging into a single global disease ecology