The document discusses disease causation and determinants. It explains that disease has multiple causes including genetic, environmental, and lifestyle factors. A model for infectious disease causation includes the agent, vector, and physical environment. Chronic disease is influenced by a web of causal factors. Key determinants of health include nutrition, genetics, socioeconomic status, and access to healthcare. The document also explains the iceberg phenomenon, where clinically apparent disease (the tip of the iceberg) represents only a small portion of total disease burden, with subclinical and undiagnosed cases forming the larger submerged part.

1. Concept of Disease Causation (Determinants &
Iceberg)
Foundation Module - 2

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Foundation Module - 2
1 Introduction to public health 11 Introduction to demography
2 Concept of disease causation
(determinants & iceberg)
12 Vital Statistics
3 Natural history of disease & Levels
of prevention
13 Morbidity & mortality
determinants
4 Dynamics of Disease
14 Population pyramid &
interpretation
5 International health agencies- WHO,
UNICEF
15 Introduction to infections
&control of infections
6 Health Care System (health system
of Pakistan included)
16 Emerging & Re-emerging
diseases
7 Primary Health Care
17 Disease screening &
Surveillance
8 Introduction to environmental
health
18 Health Information, Education
and Communication
9 Nuclear medicine 19 Waste Disposal
10 Genomics
AIR,
WATER
&
NOISE
POLLUTION
&
THEIR
PREVENTION

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Introduction to Environmental Health
Climate Change & Global Warming

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Introduction to Environmental Health
Climate Change & Global Warming

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Introduction to Environmental Health
Climate Change & Global Warming

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Introduction to Environmental Health
Climate Change & Global Warming
Weather refers to
atmospheric conditions
that occur locally over
short periods of time —
from minutes to hours or
days.
Examples include rain,
snow, clouds, winds,
floods or thunderstorms.
Climate refers to the
long-term regional or
even global average of
temperature, humidity
and rainfall patterns
over seasons, years or
decades.
A fossil fuel is a fuel formed by
natural processes. Coal, Oil, Natural
Gas.

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Climate Change & Global Warming
Global warming is the
long-term heating of
Earth’s climate system
observed since the pre-
industrial period
(between 1850 and
1900) due to human
activities, primarily fossil
fuel burning, which
increases heat-trapping
greenhouse gas levels
in Earth’s atmosphere.
Climate change is a long-
term change in the
average weather patterns
that have come to define
Earth’s local, regional and
global climates.
Both human- and
naturally produced
warming

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Climate Change & Global Warming

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Climate Change & Global Warming
The greenhouse effect
is the way in which heat
is trapped close to the
surface of the Earth by
“greenhouse gases.”
The greenhouse effect is
a process that occurs
when gases in Earth's
atmosphere trap the
Sun's heat. This process
makes Earth much
warmer
Greenhouse gases are
gases in Earth’s
atmosphere that trap
heat. The main
greenhouse gases are:
Water vapor
Carbon dioxide
Methane
Ozone
Nitrous oxide
Chlorofluorocarbons

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Climate Change & Global Warming

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Concept of Disease Causation (Determinants & Iceberg)
Learning Objectives:
Discuss the concept of disease causation
List determinants of disease
Discuss iceberg phenomenon

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Discuss the Concept of Disease Causation
The World Health Organization's claim that
health is “a state of complete physical, mental
and social well-being, not merely the absence of
disease or infirmity”
Disease “a condition in which body health is
impaired.”
Concepts are defined as abstract ideas or general notions that occur in the
mind, in speech, or in thought. Abstract ideas are concepts that need to be
visualized, as they cannot be illustrated through concrete (real) examples.
Notion(belief, idea, concept)

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Discuss the Concept of Disease Causation
Cause: An event, condition, or characteristic
without which the disease would not have
occurred.
Risk factor is a variable associated with an
increased risk of disease or infection.
Causation: identifying the causes of disease (both
modifiable and nonmodifiable) so that the disease or its
consequences might be prevented.

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Discuss the Concept of Disease Causation

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Discuss the Concept of Disease Causation

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Discuss the Concept of Disease Causation

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Discuss the Concept of Disease Causation
Applicable for Infectious Diseases

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Discuss the Concept of Disease Causation
MALARIA: Agent(Plasmodium)  Vector (Mosquito) 
Physical Environment

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Discuss the Concept of Disease Causation
Time accounts for incubation periods, life expectancy of the
host or the pathogen, and duration of the course of illness or
condition.

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Discuss the Concept of Disease Causation

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Discuss the Concept of Disease Causation
This model is ideally suited in the study of chronic disease
The "web of causation" considers all the predisposing factors of
any type and their complex interrelationship with each other.
Host (Intrinsic factors/Genetic) --- Inhibitors of Disease (Diet,
Exercise) --- Promoters of Disease (Stress, Smoking, Sedentary
Lifestyle).

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Discuss the Concept of Disease Causation

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Discuss the Concept of Disease Causation

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Discuss the Concept of Disease Causation

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Discuss the Concept of Disease Causation

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Discuss the Concept of Disease Causation
Hub
(Host/Human)

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Discuss the Concept of Disease Causation
The relative sizes of the different components of the wheel depend upon
the specific disease problem.
/Measles
Hereditary Diseases

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List Determinants of Disease
Determinants of Health: The factors which determine the
health of an individual could be inside the body
(genetic/intrinsic factors) or / and outside the body
(environmental factors). The interaction of these factors
may either promote or deteriorate the health.
Determinant: any factor, whether event, characteristic, or
other definable entity, that brings about a change in a
health condition or other defined characteristic.

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List Determinants of Disease
Nutrition
Lifestyle Environment
Genetics
Physical
Biological
Social
Socioeconomic circumstances
Level of Education
Type of Employment
Type of housing
Cultural norms /health beliefs
Access to quality health services

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List Determinants of Disease
Health Determinants Model - Dahlgren and Whitehead

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List Determinants of Disease

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Discuss Iceberg Phenomenon
 Iceberg phenomenon of disease gives a picture of the
spectrum( spread, variety) of diseases in a community.
Clinical Horizon
What the
physician sees
What the
physician
does not see
The visible part of the iceberg
(tip) denotes the clinically
apparent cases of disease in
the community.
The part of the iceberg
below the water level
(submerged) denotes the
latent, subclinical,
undiagnosed and carrier
states in the community,
which forms the major
part.
Latent S/S –ve/transmission –ve Carrier S/S –ve/transmission +ve
Water Line

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Discuss Iceberg Phenomenon
The iceberg phenomenon is a metaphor emphasizing that
for virtually every health problem the number of known
cases of disease is outweighed by those that remain
undiscovered.

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Discuss Iceberg Phenomenon
 Hence any problem/disease cannot be controlled if the
submerged portion is not given due attention ON TIME.
 Merely the treatment of the cases (tip) will not control
the problem, as if the tip is dissolved by treatment, after
some time, a huge portion (submerged) will appear on
the surface which will become uncontrollable.
How to manage the submerged portion?
The high risk population should be SCREENED/SCREENING.

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Discuss Iceberg Phenomenon
EXAMPLES OF ICEBERG OF DISEASE
Diabetes, Hypertension, Malnutrition, Polio, Leprosy.

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Discuss Iceberg Phenomenon
EXAMPLES OF ICEBERG OF DISEASE
Diabetes, Hypertension, Malnutrition, Polio, Leprosy.

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Discuss Iceberg Phenomenon

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Discuss Iceberg Phenomenon – OSPE/MCQ
 Spectrum of diseases in a community.
 TIP - Physician sees - Clinically apparent cases of
disease.
 Submerged - Physician does not see - latent,
subclinical, undiagnosed and carrier states (major part).
 Submerged portion – identify ? – Screening
 Examples: Diabetes, Hypertension, Malnutrition, Polio,
Leprosy.

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SUMMARY

47. Dr Athar Khan
Liaquat College of Medicine & Dentistry
Karachi, Pakistan
matharm@yahoo.com
MBBS, MPH, DPH, MCPS, MBA, DCPS-HPE, PGD-Statistics,
CCRP
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