Transcript 3rd Lecture

‫بسم هللا الرحمن الرحيم‬
CHAIN OF INFFECTON
THE CHAIN OF INFFECTION
Agent factors
 It is a substance, living or non-living, or
a force tangible or intangible, the
excessive presence or relative lack of
which may initiate or perpetuate a
disease process.
 A disease may have a single agent, a
number of independent alternative
agents or a complex of two or more
factors whose combined presence is
essential for the development of the
disease.
Types of Causative Agents
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Biological agents
Nutrient agents
Physical agents
Chemical agents
Mechanical agents
Absence or insufficiency or excess of a
factor necessary to health
 Social agents
Host factors
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Demographic : age, sex, ethnicity
Biological: genetic factors,
Biochemicals levels of blood, hormones,
functions of organs.
Social and economic: socio-economic
status, education, occupation, stress,
marital status, housing, etc.
Lifestyle factors: personality traits,
living habits, nutrition, physical exercise,
use of alcohol, drugs and smoking etc.
Environmental factors
All that which is external to the
individual human host, living and
non living and which he is in
constant interaction.
 Physical Environment
 Biological Environment
 Psychosocial Environment.
Psychosocial Environment
 Those factors affecting personal health, health
care and community wellbeing that stem from
the psychosocial make up of individuals and
structure and functions of social groups.
 Cultural values, customs, habits, beliefs
 Attitude, morals, religion, education
 Life style, Community Life, Health services
 Social & political Organization.
POSITIVE IMPACT
Improve Health
Provide opportunities
Improve quality of Life
NEGATIVE IMPACT:
Poverty, Urbanization, Migration, Stressful
Conditions, bereavement, desertion, loss of
employment, handicapped child, anxiety,
depression, Anger, frustration.
Risk factors
 An attribute or exposure that is significantly
associated with the development of a disease
 A determinant that can be modified by
intervention, thereby reducing the possibility of
occurrence of a disease or other specified
outcome.
 Non –Modifiable ( immutable)
Age, Sex, Genetic Factors & ethnicity.
 Modifiable Factors ( mutable)
Smoking, hypertension, elevated serum
cholesterol, physical inactivity, obesity, etc..
Risk Approach
Something for all, but more for
those in need - in proportion to
the need" Therefore it is stated
that risk factor is a proxy for
need'- indicating the need for
promotive and preventive health
services.
Prominent Risk Factors
Diseases
Heart disease
Risk Factors
Motor vehicle
accidents
Smoking, high blood Pressure, elevated
serum cholesterol, diabetes, obesity, lack of
exercise, type A personality
Smoking, alcohol, solar radiation, ionizing
radiation, work-site hazards, environmental
pollution, medications, infectious agents,
dietary factors.
High blood pressure, elevated cholesterol,
smoking.
Alcohol, non-use of seat belts, speed,
automobile design, roadway design
Diabetes
Obesity, diet
Cancer
Stroke
Cirrhosis of liver Alcohol
“AT RISK GROUPS”
Biological situation:
- age: infants (low birth weight), toddlers, elderly
- sex: females in the reproductive age period
- physiological state: pregnancy, cholesterol level, high
blood pressure
- genetic factors : family history of genetic disorders
- others: disease, physical functioning, unhealthy behavior
Physical situation:
- rural, urban slums
- living conditions, overcrowding
- environment: water supply, proximity to industries
“AT RISK GROUPS”
Sociocultural situation:
- social class
- ethnic and cultural group
- family disruption, education, housing
- customs, habits and behaviour like
smoking, lack of exercise, over-eating,
drug addicts)
- access to health services
- lifestyles and attitudes
Disease Control
An ongoing operation to reduce:
i. The incidence of disease
ii. The duration of disease
iii. The risk of transmission.
iv. The effects of infection, including both the
physical and psychosocial complications
v. The financial burden to the community.
The disease “agent” is permitted to persist in the
community at a level where it ceases to be a
public health problem.
Disease Elimination
Between control and eradication.
Elimination is used to describe
interruption of transmission of
disease from large geographic
regions or areas.
Disease Eradication
Termination of all transmission of
infection by extermination of the
infectious agent from the whole
world.
Eradication is an absolute process.
It is all or none phenomenon.
Monitoring
The performance and analysis of routine
measurements aimed at detecting
changes in the environment or health
status of population.
The continuous oversight of activities to
ensure that they are proceeding
according to plan.
Surveillance
The continuous scrutiny of the
factors that determine the
occurrence and distribution of
disease and other conditions of ill –
health. It includes the collection,
analysis, interpretation and
distribution of relevant data for
action
Objectives
•To provide information about new
and changing h. problems
•To provide feed-back which may
be expected to modify the policy
and redefine objectives.
• Provide timely warning of public
health disasters so that
interventions can be mobilized
Iceberg of disease
LEVELS OF PREVENTION
1. Primordial Prevention
Prevention of emergence or development
of risk factors in country or population
groups in which they have not yet been
appeared.
Discourage to adapt harmful lifestyle.
THROUGH: Individual education
Mass education.
2. PRIMARY PREVENTION
 An action taken prior to the onset of disease,
which removes the possibility that disease will
occur.
 Intervention in the pre-pathogenesis phase of a
disease or H. problem,
 To promote general health
 To promote quality of life
 By 1: adapting specific measures.
2: Elimination/modification of risk factors
STRATEGY: Population & High risk
3.SECONDARY PREVENTION
Action which halts the progress of a disease at its
incipient stage and prevents complications.
Early Diagnosis &
Adequate treatment.
To arrest the disease process
Restore health by seeking unrecognized disease
Prompt treatment before irreversible changes occur
Reverse communicabilty of infectious disease.
4. TERTIARY PREVENTION
All measures available to reduce or limit
impairment and disabilities, minimize
sufferings and promote patient’s
adjustment to irremediable conditions.
 intervention in late pathogenesis
 Intervention to limit disability
MODES OF INTERVENTION
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Any attempt to intervene or interrupt the
usual sequence in the development of
disease in man.
Health promotion
Specific protection
Early diagnosis & prompt treatment
Disability Limitation
Rehabilitation.
1.HEALTH PROMOTION
A process of enabling people to
increase control over & to improve
health.
 Health education
 Environmental modifications
 Nutritional interventions
 Life style & behavioural changes
HEALTH PROMOTION
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Health education
Good standard of nutrition
Attention to personality development
Provision of good housing & recreation
Good working conditions
Marriage counseling
Sex education
Periodic selective examinations
Genetics
Environmental modifications
2.SPECIFIC PROTECTION
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USE OF SPECIFIC IMMUNIZATIONS
USE OF SPECIFIC NUTRIENTS
CHEMOPROPHYLAXIS
PROTECTION AGAINST OCCUP.HAZARDS
PROTECTION FROM CARCINOGENS
AVOIDANCE OF ALLERGENS
USE OF ENVIRONMENTAL SANITATION
CONTROL OF QUALITY PRODUCTS
PROTECTION FROM ACCIDENTS
ATTENTION TO PERSONAL HYGIENE
3.EARLY DIAGNOSIS & PROMPT
TRAETMENT
 To intercept the disease process
 To cure and prevent disease process
 To prevent secondary cases (spread)
 To prevent complications and sequelae
 To shorten period of disability
 To reduce mortality
 For better prognosis
(Critically important in chronic diseases)
3.EARLY DIAGNOSIS & PROMPT
TRAETMENT
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Case finding measures
Screening surveys
Selective examinations
Mass treatment approach
Total mass approach
Juvenile mass treatment
selective mass treatment
Disability limitation
 To prevent or halt the transition of the
disease process from impairment to
handicap.
 Adequate treatment to arrest disease process
 To prevent further complications/disability
 Provision of facilities to limit disability and to
prevent death.
Disease → Impairment → Disability → Handicap
IMPAIRMENT:
Any loss or abnormality of psychological,
physiological or anatomical structure or function.
e.g. Loss of foot
Defective vision
Mental retardation
IMPAIRMENT
visible or invisible
Temporary or permanent
Progressive or regressive
DISABILITY
Inability to carry out certain activities
“Any restriction or lack of ability to perform
an activity within the range considered
normal for a human being”.
HANDICAP
 A disadvantage for a given
individual, resulting from an
impairment or a disability, that
limits or prevents the fulfillment
of a role that is normal for that
individual (depending on age, sex,
and social and cultural factors).
Concept of disability
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Accident
Loss of foot
Cannot walk
Unemployed
Disease
Impairment
Disability
Handicap
REHABILITATION
The combined and coordinated
use of medical, social,
educational and vocational
measures for training and
retraining the individual to the
highest possible level of
functional ability.
Rehabilitation
a. Medical rehabilitation – restoration of function
b. Vocational rehabilitation – restoration of the
capacity to earn a livelihood.
c. Social rehabilitation – restoration of family and
social relationships
d. Psychological rehabilitation – restoration of
personal dignity and confidence.
“to live and work within the limits of disability
but to his capacity”.
Rehabilitation
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Establishing schools for blind
Provision of aids for crippled
Reconstructive surgery
Community facilities to retrain disabled to use
remaining capacities
Graded exercises
Changes in profession
Modification of life & full employment as possible
Education of industry to utilize rehabilitated
Use of sheltered colony
Thank you
INFECTION
The entry and development or
multiplication of an infectious agent in the
body of man or animals. An infection
does not always cause illness.
Body responds as -immune response
-disease.
CONTAMINATION
The presence of an infectious agent on a
body surface; also on or in clothes,
beddings, toys, surgical instruments or
dressings, or other inanimate articles or
substances including water, milk and
food.
POLLUTION
The presence of offensive material is
called pollution. It is distinct from
contamination.
INFESTATION
It is a state of having a parasite in or on
the body which includes arthropods or
animal parasites. The lodgement,
development and reproduction of
arthropods on the surface of the body of
man or animal, in the clothings etc.
HOST
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A person or animal that affords subsistence or
lodgement of an infectious agent under natural
conditions.
An obligate host: means the only host.
An intermediate host: in which the parasite is
in a larval or asexual state. (Secondary))
Definitive Host: in which the parasite attains
maturity or passes its sexual stage. (Primary)
A transport host: a carrier in which the
organism remains alive but does not undergo
development.
INFECTIOUS DISEASE
A clinically manifest disease of man or
animal that results from an infection.
It is a state of disorder that results from
an infection by bacteria or viruses.
e.g., cholera, Diphtheria, Tuberculosis,
measles, Chickenpox.
CONTAGIOUS DISEASE
A disease that is transmitted through
contact.
e.g. scabies, trachoma, STD and
leprosy.
COMMUNICABLE DISEASE
An illness due to a specific
infectious agent or its toxic products
capable of being transmitted directly
or indirectly from man to man ,
animal to animal or from
environment to man or animal.
EPIDEMIC
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Unusual occurrence of a disease or
health related problem and health related
behaviour in a community or region
clearly in excess of expected occurrence.
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Disease affecting a large number of
persons within a short space of time.
ENDEMIC
 It refers to the constant presence of a disease
or an infectious agent within a given
geographic area or population group.
 When the number of susceptible and immune
persons are almost equal, the disease
continues to smoulder in a community and is
always present in the community.
HYPERENDEMIC
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It expresses that the disease is
constantly present at a high
incidence or prevalence and
affects all age groups equally.
HOLOENDEMIC
 It is the high level of infection
beginning in early life and
affecting most of the child
population.
SPORADIC
 The cases occur irregularly, haphazardly
from time to time and generally
infrequently.
 The cases are so few and separated that
they show little or no connection with
each other nor a common source of
infection.
PANDEMIC
An epidemic usually affecting a large
proportion of the population, occurring
over a large geographic area such as
nation, continent or the whole world.
A world wide epidemic is a pandemic.
When the susceptibility of the whole
country or the world is increased for a
particular organism e.g. influenza
Pandemic of 1918-19.
EXOTIC
When a disease is not usually
present in a locality but is introduced
form abroad, it is called Exotic.
ZOONOSIS
An infection or infectious disease
transmissible under normal conditions
from vertebrate animals to man.
e.g. rabies, plague, bovine tuberculosis,
Anthrax, brucellosis, endemic typhus etc.
EPIZOOTIC
An outbreak ( epidemic) of disease in an
animal population.
e.g. anthrax, brucellosis, rabies.
NOSOCOMIAL INFECTION
 Hospital acquired
 An infection originating in a patient while
in a hospital or health care facility.
 A disorder associated with being in a
hospital.
 It may be unrelated with the primary
condition.
 May appear after discharge.
 Infections to the staff of the facility.
OPPORTUNISTIC INFECTION
 It is an infection by an organism that
takes the opportunity provided by the
defect in host defense to infect the host
and cause disease.
 Opportunistic infections are common in
AIDS
 E.g. Herpes,
cytomegalovirus,toxoplasma
IATROGENIC DISEASE
 Physician induced disease
 An adverse consequence of a preventive,
diagnostic or therapeutic regimen or procedure
that causes impairment, handicap, disability or
death resulting from a physician’s professional
activity.
 Can prolong hospital stay
 Requires special treatment
 Threaten life.
HOST
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A person or animal that affords subsistence or
lodgement of an infectious agent under natural
conditions.
An obligate host: means the only host.
An intermediate host: in which the parasite is
in a larval or asexual state. (Secondary))
Definitive Host: in which the parasite attains
maturity or passes its sexual stage. (Primary)
A transport host: a carrier in which the
organism remains alive but does not undergo
development.
RESERVOIR
 Any person, animal, soil, arthropod, plant
or substance in which an infectious agent
lives and multiplies, on which depends
primarily for survival and can be
transmitted to a susceptible host.
 Reservoir is a natural habitat in which an
organism metabolises and replicates.
SOURCE
 A PERSON, ANIMAL, OBJECT, OR
SUBSTANCE FROM WHICH AN
INFECTIOUS AGENT PASSES OR
IS DESSIMINATED TO THE HOST.
HUMAN RESERVOIR
CASES:
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A person in the population or study group
identified as having the particular disease,
health disorder or condition under
investigation.
clinical, biochemical, laboratory tests
Clinical cases
Sub clinical cases
Latent infection: host does not shed
infectious agent which lies dormant within the
host without symptoms.
HUMAN RESERVOIR
CARRIER:
 An infected person or animal that
harbours a specific infectious agent in the
absence of discernible clinical disease
and serves as a potential source of
infection for others.
 Carriers are less infectious
 Carriers are more dangerous than cases.
CARRIER
A Type
(a) Incubatory
(b) Convalescent
( c) Healthy
B Duration
(a) Temporary
(b) Chronic
C Portal of Exit
(a) Urinary
(b) Intestinal
(c) Respiratory
MODES OF
TRANSMISSION
DIRECT TRANSMISSION
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Direct Contact
Droplet Infection
Contact with soil
Inoculation into skin or mucosa
Transplacental (vertical)
INDIRECT TRANSMISSION
1. Vehicle-borne (water, food, milk, fruits)
2. Vector-borne
a Mechanical Transmission
b Biological Transmission
i. Propagative
ii. Cyclo – Propagative
iii. Cyclo Developmental
INDIRECT TRANSMISSION
3. Air – Borne
a Droplet nuclei
b Dust
4. Fomite – borne
5. Unclean hands and fingers
Incubation Period
The time interval between invasion by
an infectious agent and appearance
of the first sign or symptom of the
disease.
Median Incubation Period:
The time required for 50 per cent of
the cases to occur following exposure.
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USES OF INCUBATION PERIOD
a. Tracing the source of infection and
contacts
b. Period of Surveillance
c. Immunization
d. Identification of point source or
propagated epidemics
e. Prognosis
Thank you