Transcript Prevention

Disease & Prevention
Dr Muhammad Zahid Latif
Department of Community Medicine
Azra Naheed Medical College Lahore
Learning Outcome
• The learners will be able to apply levels
of prevention to different diseases.
Learning Objectives
At the end of session the students will be able to;
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Define disease and prevention
List different theories of disease causation
Define natural history of disease
Enumerate different phases of natural history
Describe Levels of prevention
Apply levels of prevention for dengue and
Hepatitis C
Few Questions
• What do you know about Health & Disease?
• What is meant by Prevention?
• Is it possible to decrease road traffic accidents?
• What are the reasons for vaccination?
Disease
• It means without ease
• A condition in which body health
is impaired
• A condition of the body, organ
or part of body in which normal function are
disrupted or deranged
• WHO defines health but there is no definition of
disease
Disease Causation
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Germ Theory
Epidemiological Triad
Multi factorial
Web of causation
Germ Theory
1.Each disease will be caused by a germ
2.Without that germ that disease will not be
caused
3.By introducing that germ , that disease can be
caused in animals experimentally,
4.And that germ can again be isolated from that
sick animal experimented with.
Epidemiological Triad
• A state of equilibrium between agent host and
environment results in health, if this
equilibrium disturbs disease will occur
• Disease is the combination of
1.
2.
3.
A harmful agent
A susceptible host
An appropriate environment
.
When the disease occurs?
Agent (SEED) factors
Disease occurs only when
the host environmental
factors make the agent
sufficient enough to cause
disease
D
Host Factors (SOIL)
Environmental
Factors
(SHOWER)
Multi factorial Causation
• Epidemiological theory is not applicable for
non infectious and chronic diseases like
coronary artery diseases etc. because it has
many causes or multiple factors.
• This theory helps to understand the various
associated causative factors, which suggests
preventive and plan measures to control the
disease
Multi factorial Theory
Web of causation
• Disease never depends upon single isolated
cause rather it develops from a chain of
causation in which each link itself is a result of
complex interaction of preceding events these
chain of causation which may be the fraction
of the whole complex is known as web of
causation.
Web of causation
The socioeconomic approach
• This model is composed of four major
categories of factors:
1. Human biology
2. Lifestyle
3. Environment
4. Health system
• All these factors influence health status
positively or negatively.
Natural History of Disease
• The natural history of disease refers to a
description of the uninterrupted progression
of a disease in an individual from the moment
of exposure to causal agents until recovery or
death or disability.
• Pre pathogenesis phase
• Pathogenesis phase
Definition
• The course of a disease from onset (inception) to
resolution.
• Stages
Progress to a fatal termination
Stage of
pathologic
onset
Pre-symptomatic
stage
Risk Factors
Precursors
Clinically
manifest disease
Remission and relapses
Regress spontaneously,
leading to recovery
Effect of Treatment
Prognostic factor
The Natural history of disease in a patient
Preclinical Phase
(A)
(P)
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Clinical Phase
(S)
(M)
(D)
A ; Biologic onset of disease
P ; Pathologic evidence of disease if Sought
S ; Signs and symptoms of disease
M ; Medical care sought
D ; Diagnosis
T ; Treatment
Gordis L. Epidemiology. WB Saunders Company. 1996
(T)
Pre Pathogenesis Phase
• This is the phase before the onset of disease
in man.
• The disease agent has not yet entered man
But the factors needed for its interaction with
the human host are already present in the
environment.
• Potentially, we are all in the pre pathogenesis
phase of many diseases.
Pathogenesis phase
• This phase begins with the entry of disease
agent into man (host).
• There is a certain interval of time before the
onset of clinical signs and symptoms of the
disease. This period is called incubation
period.
• During this period the disease agent multiplies
and induces physiological changes.
Pathogenesis Phase
• Incubation period is followed by early
pathogenesis.
• During this period, the signs and symptoms
are not clear-cut.
• This is followed by late pathogenesis when
there are clear-cut signs and symptoms.
• The final outcome of the disease may be
recovery, disability or death
Importance of natural history
• Each disease has its own natural history; but it
is not necessarily the same in all individuals.
• If the phase of natural history is known,
appropriate level of prevention can be
applied.
Disease Agents
The disease agent is defined as 'a living or
non- living substance or the excessive
presence or absence of a force which may
initiate a disease process‘.
Agent
Host
• The human host is supposed to be 'soil' and the
disease agent as the 'seed'. The host factors are:
• 1. Demographic characteristics such as age sex
and ethnicity.
• 2. Biological characteristics such as genetic
factors, blood groups, enzymes, immunological
factors etc.
• 3. Social and economic characteristics such as
education, occupation, income, housing etc.
• 4. Life-style factors such as nutrition, exercise, use
of alcohol, drug abuse, smoking etc.
Host
Environment
• The environment in which man lives is an
important factor in the causation of diseases.
Environment is classified as:
• 1. Physical environment
• 2. Biological environment
• 3. Psychological environment.
Environment
Iceberg of Disease
(what the physician sees, clinical cases)
Goals of Medicine
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Promote & Preserve health
Restore health when it is impaired
Minimize suffering and distress
All these goals are covered in one word
Prevention
The action of stopping something from happening or arising is called
prevention.
Prevention depends upon
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Knowledge of causation
Dynamics of transmission
Risk factors
Risk groups
Early detection and treatment measures
An organization
Evaluation
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Primordial Prevention
Primary Prevention
Secondary Prevention
Tertiary Prevention
Primodial Prevention
• It is primary prevention in its purest form.
• It is the prevention of the emergence or
development of risk factors in countries or
population groups in which they have not yet
appeared
Primordial Prevention
• Many adult health
problems have their
early origins in childhood,
because this is the time
when lifestyles are formed
(for example, smoking,
eating patterns, physical
exercise).
Primodial Prevention
• Efforts are directed towards discouraging
children from adopting harmful lifestyles
• Main intervention in primordial prevention is
through individual and mass education
Primary Prevention
• Defined as the action taken prior to the onset of
disease, which removes the possibility that the
disease will ever occur.
• It signifies intervention in the pre-pathogenesis
phase of a disease or health problem.
• Primary prevention may be accomplished by
measures of “Health promotion” and “specific
protection”
Primary Prevention
Health Promotion
Specific Protection
Health Education
Immunization
Environmental modification
Chemoprophylaxis
Nutrition Intervention
Specific Nutrients
Life style & Behavioral Changes
Safety of drug and food
Control of environment hazards
Approaches for Primary Prevention
• According to WHO
1. Population (mass) strategy
2. High -risk strategy
Population (Mass) Strategy
• Population strategy" is directed at the whole
population irrespective of individual risk
levels.
• This approach is directed towards socioeconomic, behavioral and lifestyle changes
High risk Strategy
• The high -risk strategy aims to bring
preventive care to individuals at special risk.
• This requires detection of individuals at high
risk by the optimum use of clinical methods.
Secondary Prevention
• defined as “ action which halts the progress of
a disease at its incipient stage and prevents
complications.”
• Attempts to arrest the disease process, restore
health by seeking out unrecognized disease
and treating it before irreversible pathological
changes take place, and reverse
communicability of infectious diseases.
Tertiary Prevention
• It is used when the disease process has
advanced beyond its early stages
• defined as “all the measures available to
reduce or limit impairments and disabilities,
and to promote the patients’ adjustment to
irremediable conditions.”
• Intervention that should be accomplished in
the stage of tertiary prevention are disability
limitation, and rehabilitation
Intervention
• Intervention is defined as
1. the act or fact of interfering so as to modify.
2. any measure whose purpose is to improve health or
alter the course of disease.
3. Intervention is an attempt to intervene or interrupt the
usual sequence in the development of disease in a man
Modes of Intervention
1.
2.
3.
4.
5.
Health Promotion
Specific Protection
Early Diagnosis and treatment
Disability Limitation
Rehabilitation
Health Promotion
It is a process of enabling people to increase control
over & to improve health. It is intended to
strengthen host
1.
2.
3.
4.
5.
Health education
Environmental health
Nutritional intervention
Lifestyle changes
Behavior changes
Specific Protection
It is a process to totally avoid disease or illness
1.
2.
3.
4.
5.
6.
7.
Immunization
Nutritional supplement
Chemoprophylaxis
Immunoprophylaxis
Protective device in industry
Protective device against carcinogen
Protective device against allergens
Early Diagnosis & Treatment
It is a process of early detection of transformation from physiological to
pathological state
Early diagnosis and prompt treatment of:
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Ca breast
Ca cervix
TB
Leprosy
Disability Limitation
• In late pathogenesis phase
• Objective is to prevent or halt the transition of
the disease process from impairment to
handicap
Impairment, Disability, Handicap
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Anwer is a 4-years old who has a form of cerebral palsy (CP)
. His CP causes his legs to be stiff, tight, and difficult to
move. He cannot stand or walk.
• Impairment: The inability to move the legs easily at the joints
and inability to bear weight on the feet is an impairment.
• Disability: Anwer's inability to walk is a disability.
Handicap: Anwer's cerebral palsy is handicapping to the
extent that it prevents him from fulfilling a normal role at
home, in preschool, and in the community.
Rehabilitation
• It is a combined & co-ordinated use of
medical, social, economical, vocational and
psychological measure for training and
retaining the individual to the highest possible
level of functional ability.
Rehabilitation
1.
2.
3.
4.
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Medical rehabilitation
Social rehabilitation
Economic rehabilitation
Vocational rehabilitation
Psychological rehabilitation
Natural history of disease
Reaction of the host to the stimulus
Interrelation of Agent , Host and Environmental
Factor
Production of stimulus
Early
pathogenesis
Discernible early
lesions
•Health Education
•Good standard of
nutrition adjusted to
developmental phases
of life
•Attention of
personality
development
•Provision of adequate
housing recreation &
agreeable working
cond.
•Marriage counseling
ang sex education
•Genetics
•Periodic selective
examination
Specific protection
•Use of specific
immunization
•Attention to personal
hygiene
•Use of environmental
sanitation
•Protection against
occupational hazards
•Protection from
accidents
•Use of specific
nutrients
•Protection of
carcinogens
•Avoidance of allergens
Primary prevention
Convalescence
Period of Pathogenesis
Pre-pathogenesis period
Health Promotion
Advance
disease
Early diagnosis & prompt
treatment
Disability
limitation
Rehabilitation
•Case finding measures
•Adequate
•Provision of hospital &
individual & mass
•Screening surveys
•Selective examinations
objectives
To cure & prevent disease
process
To prevent the spread of a
communicable diseases
To prevent complications &
sequel
To shorten period of disability
treatment to
arrest the disease
process and to
prevent further
complications
community facilities for
retaining & education
for maximum use of
remaining capacities
•Education of public &
industry the
rehabilitated
•As full employment as
possible
•Selective placement
•Work therapy in
hospitals
•Use of shelter colony
Secondary Prevention
•Provision of
facilities to limit
disability and to
prevent death
Tertiary prevention
• Application of Levels of Prevention for Dengue
and Hepatitis C