Medical Approach vs. Public Health Approach
Geography 280
Introduction
*
Medical Approach vs. Public Health Approach
-
- Medical approach– individual treatment
-
- Public health approach—populations
- Sometimes called “population health”
- We’ll emphasize population approach
*
Basic Concepts–Health
Absence of symptoms/signs
WHO: state of complete well-being (physical, social, psychological, spiritual)
Ability to function “normally”
Disease Concepts
-
- Infectious
-
- Apparently non-infectious
- Increasing realization: role of genetics in both
Infectious
-
- Caused by “pathogens”
- Viruses, bacteria, helminths (etc)
- Where put prions?
-
- Infection does not imply disease
-
- Most infectious diseases are “transmissible” or “communicable”
Modes of transmission
- Respiratory https://www.youtube.com/watch?v=9qqHOKUXY5U)
http://www.discovery.com/tv-shows/mythbusters/videos/slow-motion-sneezes/
Modes (continued)
- Direct contact
- Fomites (objects)
- Sexual/body fluids/bloodborne
- Vectorborne
- Fecal-oral
- Waterborne
- Foodborne
A few measures
- Mortality
- Number of deaths
-
- Morbidity
- Illness/disease
More measures
-
- Prevalence—total number of cases of a disease in a population
-
- Incidence— number of new cases in a population
*
Rates
-
- Must divide by population
-
- Prevalence rate:
- Total number of cases/population (at risk)
- We’ll use this one: it can get more complex
- Incidence rate:
- For our purposes:
- # new cases/pop at risk
INCIDENCE RATE
Measures (cont)
- Case fatality rate (ratio)
- Total number of deaths due to a cause/total number of cases
Clinical Infectious Diseases, Jan 15, 2013
Geography
Patterns of place and space
What are the geographic patterns of disease?
Why?
How does disease spread (place-place)?
Approaches in this class
-
- Spatial
- What is the “geometrical” distribution of disease/health?
-
- “Human-environment” approach
- Influence of environment on health
- Interaction of:
- Biology
- Environment
- Culture, society
Human-environment interaction
-
- DISEASE ECOLOGY:
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- Environment (habitat)
-
- Population (incl genetics)
- Behavior
Epidemiology
-
- Purpose: understand patterns, cause, prevention
- Descriptive: distribution of disease by time, place, ethnicity, age,
- Analytic:
Explanation of patterns in descriptive epi—techniques from molecular, causal statistics, social
“TRIANGLE OF
HUMAN ECOLOGY
SOURCE:
Meade and
Emch, Medical
Geography
The Epidemiologic Triangle-
from Dr. Thomas songer, U of pitt
Host Factors
Personal traits
behaviors
genetic predisposition
immunologic factors
- Influence the chance for disease or its severity
*
The Epidemiologic Triangle
from Dr. Thomas songer, U of pitt
Agents
Biological
Physical
Chemical
- Necessary for disease to occur
*
The Epidemiologic Triangle
from Dr. Thomas songer, U of pitt
Environment
External conditions
Physical or biologic
or social
- Contribute to the disease process
*
Source: Meade and
Emch,
Medical Geography
state
Also google.org
Then GOOGLE EARTh
*
Non-traditional Estimates
-
- Google keywords
- Cough, fever, chills, flu, influenza, etc
See: Google Flu Trends
An example of disease spread…
Cancers
N Engl J Med 2011;365:1509-19
“The opportunity to move from a neighborhood with a high level of poverty to one
with a lower level of poverty was associated with modest but potentially important
reductions in the prevalence of extreme obesity and diabetes”
“this analysis of breast cancer clustering
in space provides evidence of geographic clustering of
pre-menopausal, but not post-menopausal, breast cancer
cases at the time of birth and menarche”
Introductory lecture
GEOG 380
Important concepts, important quotes
-
- “the pathogen is nothing; the terrain is everything”—attributed to Pasteur
- “with malaria, everything is local”
Understand the multifaceted nature of disease causation:
social
biological
environmental
political
Understand some of the major health problems faced by our global populations
Understand the interactions of:
environment
society
biology
politics
and their roles in the context of disease
Understand some of the basic features of the diseases themselves
Don’t get malaria, travelers diarrhea, TB, dengue, cholera, ……..
How did we get to our understanding of health/disease?
Hippocrates
-
- “Airs, Waters, and Places”
-
- Big emphasis on environment
- Idea that the air can be “bad”
- Italian: “mal aria”= “bad air”—not in Hippocrates in Italian
This kind of thinking persisted
-
- Idea that environment determines health
-
- But, at same time,
- Increasing understanding of anatomy, physiology, organ systems
Germ theory of disease
- Attributed to Louis Pasteur
- In fact, many around his time
- Idea that disease caused by “germs”
Turning inward of medical science
BUT………
-
- “Cities Beautiful Movement”—urban planning—clean up the city
-
- Public health movement—
- “Public health police”—translated from German
Underlying question…..
- Where do “germs” come from?
NOW
- Immense growth at molecular level
Cellular
Organ system
Individual
Group
Society
Global
Our real challenge: Understand how the molecular, cellular scales interact with social and global scales to produce health and disease
A tremendous challenge
Basic Concepts–Health
Absence of symptoms/signs
WHO: state of complete well-being (physical, social, psychological, spiritual)
Ability to function “normally”
Disease Concepts
-
- Infectious
-
- Apparently non-infectious
- Increasing realization: role of genetics in both
Infectious
-
- Caused by “pathogens”
- Viruses, bacteria, helminths (etc)
- Where put prions?
-
- Infection does not imply disease
-
- Most infectious diseases are “transmissible” or “communicable”
Modes of transmission
- Respiratory
- Direct contact
- Fomites (objects)
- Sexual/body fluids/bloodborne
- Vectorborne
- Fecal-oral
- Waterborne
- Foodborne
The Human-Environment Dichotomy
-
- “Ninety percent of cancers have an environmental component”
-
- What does this mean?
- Environment=anything external to the human body
In health and disease
-
- We are the environment, and the environment is us
-
- Air pollution
- Water pollution (microbes, toxic substances)
- Radioactive substances
- X-rays, nuclear waste, core meltdowns, etc.
In other words:
The exterior environment can become our interior environment
AND………
- We alter the environment
- Buildings
- Agriculture
- Industry
- Physiologically:
- Our wastes
- CO2 exhalation (small scale)
In environmental studies,
geography, etc
What is usually “the environment?”
A few measures
-
- Mortality
- Number of deaths
- Morbidity
- Illness OR disease
- Mortality rate= deaths in a population/population
- Example: next slide
“For Harlem, the age-adjusted rate of mortality from all causes was the highest in New York City, more than double that of US whites, and 50% higher than that of US blacks….black men in Harlem were less likely to reach the age of 65 than men in Bangladesh.”—McCord and Freeman, N Engl J Med 1990;322:173-177
Case Fatality Rate
-
- Deaths due to disease X/ total cases of X
- NOTE: This is NOT mortality rate!!!!!
watch in reading, journals for misuse of the term
More measures
-
- Prevalence—total number of cases of a disease in a population
-
- Incidence— number of new cases in a population
Rates
-
- Prevalence rate:
- Total cases of disease X/population at risk/time
- Incidence rate:
- Total number of NEW cases/pop at risk/time
“the human ecology of disease is concerned with the ways human behavior, in its cultural and socioeconomic contexts, interacts with environmental conditions to produce or prevent disease among susceptible people. This represents the etiology,
or causal evolution, of health and disease”
–Meade and Emch, Medical Geography
“Epidemiologic triangle”
-
- Agent
-
- Host
- Environment
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state
Also google.org
Then GOOGLE EARTh
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