Download Environment and Exposure

Environment, Society, Climate and Health:
Analysis, Understanding and Prediction
Mark L. Wilson
Department of Epidemiology
and
Global Health Program
School of Public Health
The University of Michigan
Colloquium on Climate and Health
NCAR
Boulder, Colorado
23 July, 2004
Outline
1. Introduction: Infectious Disease Epidemiology
2. Patterns of Environmental Influences
3. Climate as an Environmental Driver
4. Examples from our research
5. Discussion of examples from your research/interests
Climate Variability vs. Climate Change
• Climate Change:
- persistent change or trend in mean atmospheric
conditions
- current changes unprecedented in human history
• Climate Variability:
- day-to-day (weather) or relatively short term (seasonal)
changes in atmospheric conditions
- effects on disease patterns most easily analyzed, and
used in forecasts
Classical Epidemiological Triad
Environment
Agent
Host
Environment*
(biophysical, psycho-social, etc.)
Agent
Host
(diverse exposures,
including noncontagious )
(animal, plant,
ultimately human)
*CLIMATE is an Environmental Influence
Environment
Agent
Host
Examples Involving Infectious Diseases
Environment
longevity & infectivity
outside host
host distribution,
abundance, infection
e.g. cholera
hantaviral disease
hookworm
schistosomiasis
nutrition
hygiene
treatment
housing
e.g. TB, HIV/AIDS,
diarrheal diseases,
acute respiratory
infections
Agent
Host
tissue tropisms,
pathogenicity,
immune response,
host specificity
e.g. rabies,
Lyme disease,
malaria,
cryptosporidiosi.
But for ALL diseases, complex interactions occur...
Environment
Altered hygiene
Improved irrigation
Redesigned housing
Better nutrition
Agent
Host
Environment
Agent transport to new areas
New antibiotics, pesticides
Labor actions affecting toxin exposure
Agent
Host
Environment
Agent
Host
Exposure probability, host immunity,
support networks, availability of supportive care
Examples of Environmental and Epidemiological Data
•
•
•
•
•
•
•
Climate patterns – variability… perhaps change…
Land Use / Land Cover patterns
Human case data (specific or syndromic)
Vector abundance and pathogen infection
Reservoir abundance / infection prevalence
Environmental use and exposures
Economic development, human demography,
migration … more
Each of these is historically changing in
time and space
Environmental Determinants of Human Disease
Social and Economic Policies
Institutions (including medical care)
Living Conditions
Social Relationships
Individual Risk Factors
Genetic/Constitutional
Factors
Pathophysiologic
pathways
Individual/Population
Health
Modified from Kaplan, 2002
Research Challenge – Analyze and understand
interactions!
Social and Economic Policies
Institutions (including medical care)
Living Conditions
Social Relationships
Individual Risk Factors
Genetic/Constitutional
Factors
Pathophysiologic
pathways
Individual/Population
Health
Environmental Variable
What is climate change? Climate variability?
Unchanging Average, Unchanging Extremes
Average Trend
(solid line)
Actual Measure
(dashed line)
Low
Time
Environmental Variable
Unchanging Average, Increasing Extremes
Average Trend
(solid line)
Actual Measure
(dashed line)
Low
Time
Environmental Variable
Increasing Average, Unchanging Extremes
Average Trend
(solid line)
Actual Measure
(dashed line)
Low
Time
Environmental Variable
High
Different Rates of Increasing Averages
Average Trend
(solid line)
Actual Measure
(dashed line)
Low
Time
Environmental Variable
Increasing Average, Greater Extremes
Average Trend
(solid line)
Actual Measure
(dashed line)
Low
Time
Environmental Variable
Increasing Rate of Increasing Average,
Unchanging Extremes
Average Trend
(solid line)
Actual Measure
(dashed line)
Low
Time
Environmental Variable
Increasing Rate of Increasing Average,
Greater Extremes
Average Trend
(solid line)
Actual Measure
(dashed line)
Low
Time
Each of these climate change patterns
may have different impacts on particular
disease risks.
Effects will depend on the ecology of
transmission and the etiology and
expression of disease.
Each exposure type should be considered in context of:
 PERSON (age, behavior, gender, SES, etc.)
 TIME (year, season, adjacent periods, etc.)
 PLACE (geographic location, habitat, proximity, etc.)
Most Epidemiological studies only superficially consider
this for environmental (climatic) exposures:
+ PERSON most often involves standard descriptors that do
not include "social" characteristics or other environmental
exposures (e.g. climatic).
 TIME is rarely dynamic, considers only recent past, and
climate pattern over long periods not always available.
 PLACE often ignored or not carefully evaluated (e.g. spatial
autocorrelation, climate patterns in regions may be important
Environment and Exposure
Direct Exposure
Indirect Exposure
Environmental Exposures
Source
Source
Vehicle
Humans
Humans
Solar UV
EM Radiation
Tetanus
Stream pollutants
Air Particulates
Legionella
Anthroponotic Infections
Humans
Humans
Vehicle
Humans
Vehicle
Humans
STDs
Measles
Hepatitis B
Malaria
Dengue
Roundworm
Zoonotic Infections
Animals
Animals
Vehicle
Animals
Humans
Vehicle
Animals
Anthrax
Ebola (?)
Humans
Lyme Disease
Hantaviral Disease
Environment and Exposure
Where might Climate Impact?
Direct Exposure
Indirect Exposure
Environmental Exposures
Source
Source
Vehicle
Humans
Solar UV
EM Radiation
Tetanus
Humans
Stream pollutants
Air Particulates
Legionella
Environment and Exposure
Where might Climate Impact?
Direct Exposure
Indirect Exposure
Anthroponotic Infections
Humans
Humans
Vehicle
Humans
STDs
Measles
Hepatitis B
Vehicle
Humans
Malaria
Dengue
Roundworm
Environment and Exposure
Where might Climate Impact?
Direct Exposure
Indirect Exposure
Zoonotic Infections
Animals
Animals
Vehicle
Animals
Humans
Vehicle
Animals
Anthrax
Ebola (?)
CJD
Humans
Lyme Disease
Hantaviral Disease
Most arboviral diseases
Elements of Climate and Health
Maximum Temperature
Heat-related mortality
Minimum Temperature
Extreme Events
Mean Temperature
Air Pollution
Rainfall Amount
Vector-borne Diseases
Rainfall Frequency
Water-borne Diseases
Rainfall Rate
Agricultural Production
What diseases are climate sensitive?
Sensitivity
High
Moderate
– Which are more
sensitive????
• Less sensitive
– What about less
sensitive???
Low
Sensitivity
• More sensitive
Lowest
What diseases are climate sensitive?
Sensitivity
High
Moderate
–
–
–
–
–
–
–
heat stress
effects of storms
air pollution effects
asthma
vector-borne diseases
water-borne diseases
food-borne diseases
• Less sensitive
– sexually transmitted
diseases
– violence
– most cancers
– atherosclerosis
– tuberculosis
– myocardial infarction
Low
Sensitivity
• More sensitive
Lowest
Sexually transmitted
Disease
Heat stress
Effects of Storms
Water-borne disease
Food-borne disease
Asthma
Atherosclerosis
Vector-borne Disease
Cancer (not skin)
Myocardial Infarction
Violence
More Climate Sensitive
Discussion…
From YOUR EXPERIENCES or INTERESTS:
• What diseases might have a climate link and what
climate variables might impact on which diseases?
• WHY? What are the biological or social pathways?
• How would these be investigated/researched?
• What additional information would you seek?
• How would you integrate this into OTHER
determinants of risk?
• Could you forecast risk based on these analyses alone?
• What other factors should be considered and why?
Importance of temporally and spatially extensive data in
analyzing and interpreting role of climate:
• Climate change occurring over long time period
• Climate variability change not easy to recognize
without long-term observations
• Time-space changes in disease patterns require
accurate and consistent surveillance (often nonexistent, especially in developing countries)
• Inference of climate-disease links limited without
carefully considering time-space patterns
Interpreting Spatial Patterns of Risk
a
b
•Area of risk
•Size of areas
•Location and pattern
•Inter-area distances
•Connectivity among
locations
c
d
How can extensive time-space datasets help?
Pattern of disease
… or knowledge, SES,
exposure, etc...
T1
T2
T3
How can extensive time-space datasets help?
Abundance / Prevalence
How can extensive temporal datasets help?
Time
Abundance / Prevalence
How can extensive temporal datasets help?
Inter-annual
Fluctuations
Establishment
and Colonization
Dispersal, Invasion,
Extinction, Reinvasion
Time
How can extensive spatial datasets help?
Abundance or Infection
Habitat
Fragmentation
Distance
from Source
Climate variable
Change in
Suitable Habitat
Low
Low
Environmental Index
High
Some Sources of Data
•
•
•
•
•
•
Meteorological Stations (climate, weather)
Satellite – climate, vegetation, soil moisture, etc
Census: population, age, sex, location, etc…
Passive or active surveillance of human cases
Surveillance of vector, reservoir abundance
more...
Knowing is not enough; we must apply.
Willing is not enough; we must do.
(Goethe)