epidemiological transition Flashcards
what is the epidemiological transition theory?
proposed by Omran, a framework to understand changes in disease patterns in Europe
idea that mortality in human history has shifted from being from infectious disease, to chronic, degenerative disease.
past: infectious diseases caused most death, due to pathogens transmitted with/without contact
present: chronic/degenerative disease due to aging, lifestyle, toxins, etc.
what were Omran’s proposed 3 ages?
Age of Pestilence/Famine (until 1875)
Age of Receding pandemics (1875-1930)
Age of Degenerative and Man-Made diseases (1930-present)
movement from one stage to the next involves decline in mortality and increased life expectancy
what diseases were prevalent in the age of receding pandemics
pneumonia
influenza
TB
diarrhea
heart disease
nephritis
accidents
cancer
diphtheria
meningitis
what diseases are prevalent in age of degenerative disease
heart disease
cancer
stroke
accidents
pneumonia
influenza
arteriosclerosis
diabetes
circulatory disease
what was naively believed in 190s
that the world was done with great pandemics, unless something crazy like war or famine changed things
what are some limitations to Omran’s Theory?
restricted to European data
emerging and resurging infections not foreseeable
relatively short time scale when compared to millions of years in human history
3 epidemiological transitions from Armelagos
Palaeolithic baseline: hunter-gatherers substinance pattern (until 10k years ago)
First transition: food production + urbanization (10,000 - 100 years ago)
Second transition: industrialization
Third transition: post-industrial
what are the classic epidemiological shifts?
0: inherited from last common ancestor over 100,000 years ago. ex. co-divergence of hosts and pathogens
1: agriculture about 10,000 years ago. zoonoses from livestock, increased population density. ex. TB
2: urbanization 5000 years ago. increased population density. ex. measles
3: colonization in last 500 years. increased likelihood of human mediated dispersal of pathogens, human and non human. ex. yellow fever
4: globalization. hyperconnected global populations and large scale anthropogenic environmental change (ex. SARS)
describe the neolithic transition/ what did the adoption of agriculture and animal domestication do for health?
agriculture = worse health
sedentism increased amount of infectious agents in immediate environment, and increased population density increased transmission probabilities
proximity to and constant contact with animals leads to increased chance of host jumping
concentration on fewer sources of food = reduced nutrition, so you have nutritional disease which reduces immune response to infectious disease
What did urbanization do to health?
state formation and aggregate societies have had unique and on-going impacts on human societies
urbanization marks a shift towards a densely populated, permanent population. more pathogens in environment, more susceptible ppl close together.
what did colonization and colonialism due to health?
exploitation of one society by another to extract value + power. global trade network, populations mix and so do their pathogens
what did globalization do to health?
massive interconnection of human populations across continents facilitated by rapid transportation. epidemics now can become pandemics, which complicates disease control
emerging infectious diseases
EIDs are infectious diseases newly recognized in population
Re-EID is an infectious disease that has existed but is making a comeback in a region
(emerge = come into view)
when do diseases emerge?
distinct symptoms
new diagnostic methods
disease develops slowly, host lives longer
local disease becomes widespread
previously tolerated, now unacceptable
rare disease becomes common
mild disease becomes severe
diffuse disease begins to cluster
marginal group gains public voice
new population comes into view
which processes favour disease emergence?
travel of people and vectors (ex. malaria)
human demography (increasing population density and urbanization = crowing + poor sanitation)
microbial adaptation and change (microbial resistance, mutations)
climate change (expands vector range, land use changes)
technology, industry, agriculture (new methods of food production, BSE in cows but CJD in humans. avian influenza in chicken farms)
breakdown in public health measures (idea infectious disease has been conquered)
poverty
lack of access to resources and healthcare
