community medicine

1. Concept of health and disease

2. HEALTH
It Is Not an Issue Of
Medical Professionals,
Social Service Or Hospital.
BUT ITS AN ISSUE OF
SOCIAL JUSTICE.

3. Concept of Health

4. Concept of health
 The oldest definitions is absence of disease
 In 1977,30th World health assembly & WHO decided to
achieve ‘HEALTH FOR ALL’ by the year 2000.

5. CHANGING CONCEPT OF HEALTH
(Based on individual’s perspective)
HEALTH
BIOMEDICA
L
CONCEPT
ECOLOGIC
ALCONCEPT
PSYCHOSOCIA
L
CONCEPT
HOLISTIC
CONCEPT
(Based on germ
theory of disease)
Human body=machine
Disease = breakdown
Doctor = repair
(Relative absence
of pain and
discomfort and
continuous
Adaptation of man
to his
environment)
(Influenced
by social,
psychological
economic
cultural &
political
factors)
Sound mind in
sound body, in
sound family ,
in sound
envmnt)

6. WHO Definition of Health
Health is a state of complete physical, mental and
social well-being and not merely an absence of
disease or infirmity
and ability to lead socially and economically productive life
Operational definition:
A condition or quality of human organism expressing the adequate
functioning of the organism in giving condition, genetic or environmental

7. LIMITATIONS:-
*Health is not static concept but a
dynamic process.
*Nobody can be qualified healthy based
on above definition.
*In spite of above limitations,
concept of health by WHO is
widely accepted since it
reflects positive health.

8. Dimensions
 As per WHO definition three specific dimensions are
Physical Mental and Social
 But many more can be cited namely
 Spiritual
 Emotional
 Vocational
 Political dimensions

9. Physical Dimension
 Perfect functioning of the body
 It conceptualizes health biologically as a state in
which every cell and every organ is functioning
at optimal capacity and in perfect harmony with
the rest of the body.
 Assessment of physical health at individual level
can be done by
 Inquiry into symptoms of ill health, Risk factors,
Medications, Physical activities etc
 Where as at community level by death rates,
Infant Mortality rate, expectation of life etc.

10. Mental Dimension
 Mental health is not mere absence of mental illness,
 Good mental health is the ability to respond to the
many varied experiences of life with flexibility and
a sense of purpose.
 Psychologists have mentioned the following
characteristics as attributes of a mentally healthy
person:
 Mentally healthy person is free from internal conflicts: he is
not at war with himself.
 He is well- adjusted i.e. he is able to get along well with
others. He accepts criticism and is not easily upset.
 He searches for identity
 He has strong sense of self esteem
 He knows himself: his needs, problems, and goals.
 He has good self control balances rationality and
emotionality
 He faceas problems and tries to solve them intelligently i.e.
coping with stress and anxiety.

11. 12-POINTS FOR YOUR
STRESS MANAGEMENT & PROMOTION OF MENTAL HEALTH
M – Minimize your needs, lead a simple & content full life. Money
management : Be wise in earning and spending Money.
E – Expectation about other : To be reduce. Persuade them to
understand and live comfortably with you. Empathize with them.
N – Negative Thinking: To be change to positive thinking.
T – Today should get Importance, not to the past, not the future.
Try to be happy today.
A – Accept Reality: Adapt your self to it. Appreciate your self &
others.
L – Loneliness to be avoided. Get support of others. Develop
religious & Spiritual activities join social organizations.

12. H – Hobbies to divert your attention to relax: Music, Reading creative
activities, Sports, Yoga meditation.
E – Express your feelings with some one you like / write dairy / keep good
environment.
A – Be active enjoy the work you do. Keep your self Busy.
L – Learn skills, improve your knowledge to manage your problems. Prepare
& Manage life events.
T – Take things as they come. Tackle one problem at a time. Have realistic
targets.
H – Healthy life style-Regular food –Exercise (walking), good living
environment. Treatment for health problems from family doctor.

13. Social Dimension
 It may be said as the quantity and quality of an
individual’s interpersonal ties and the extent of
involvement with the community.
 Social health takes into account that every individual
is part of wider community and focuses on social and
economic conditions and well-being of the whole
person in context of his social network.

14. Spiritual Dimension
 Spiritual health refers to that part of the
individual which reaches out and strives for
meaning and purpose in life.
 It includes integrity, principals, and ethics, the
purpose in life, commitment to some higher
being and belief in concepts that are not
subjected to state of the art explanation

15. Emotional Dimension
 Historically the mental and
emotional dimensions have
been seen as one element, or
closely related elements.
 Research proved as
 Mental health as knowing or
cognition while Emotional
health as feeling

16. Vocational Dimension
It is a new dimension
The importance of this dimension is
exposed when individual suddenly
lose their jobs or faced with
mandatory retirement.
For many individuals the vocational
dimension may be the merely source
of income
For other it represents the
culmination of the efforts of other
dimensions as they function together
to produce what the individual
considers life Success

17. others
 Cultural dimensions
 Socio-economic dimensions
 Environmental dimensions
 Educational dimensions
 Nutritional dimensions
 Curative dimensions
 Preventive dimensions

18. Positive Health
 As per WHO definition “ Health is a state of complete
physical, mental, and social wellbeing and not merely an
absence of disease or infirmity”
 It is the harmonious balance of this state of the human
individual integrate into his environment, constitutes
health as per defined by WHO.

19.  The concept of perfect positive health cannot become a
reality because man will never be so perfectly adapted to
his environment that his life will not involve struggles,
failures and sufferings.
 Health in this context has been described as a potentiality-
The ability of an individual or a social group to modify
continually to changing condition of life

20. Health - A Relative concept
 An alternative approach to positive health conceptualizes
health not as an ideal state, but as a biologically “Normal”
state, based on statistical averages.
 E.g. Birth weigh of average Indian child is 2.8kgs. Is normal as
compared to 3.5kgs. In the developed countries.
 This implies that health is a relative concept and health
standards vary among cultures, social classes and age group.
Thus health standards need to be set as per the prevailing
ecological conditions rather then universal health standards.

21. CONCEPT OF WELLBEING
 WHO definition of health introduces the concept of
wellbeing.
Types
 Objective components related to “Standard Of
Living” or “Level Of Living”
 Subjective components referred to as “Quality Of
Life”

22. Objective components
Standard of living:
 Refers to the usual scale of our expenditure, the
goods we consume, and the services we enjoy.
 As per WHO “Income and occupation, Standards of
housing, Sanitation and nutrition, The level of
provision of health, education recreational and other
services”
 May all be used individually as measures of socio-
economic status and collectively as an index of the
Standard of living.

23. Level of living:
 It consist of nine components “Health, Food
consumption, Education, Occupation and working
conditions, Housing, Social security, Clothing,
Recreation and leisure and Human rights ”.
 These objective characteristics are believed to
influence human wellbeing

24. SUBJECTIVE COMPONENT
 Quality of life:
 A composite measure of physical mental and social
wellbeing as PERCEIVED by each individual or by
group of individual- that is to say happiness,
satisfaction, and gratification as it is experienced in
such life concerns as health, marriage, family, work,
financial situation, education, occupation, self
esteem, creativity, belongingness, and trust in
others.
 Types:
 Physical quality of life index
 Human development index

25. Subjective component: Quality of life:
Physical Quality Of Life Index [P Q L A ]*
It consolidates three indicators [ill]
Infant mortality
Life expectancy at age one
Literacy
 For each component, the performance of individual countries
is placed on a scale 0 to 100,
 where 0 represents an absolute define worst performance.
 And100 represents an absolutely defined best performance.
 The composite index is calculated by averaging the
indicators, giving equal weight to each of them.
 The resulting PQLA thus also is scaled.

26. P Q L A
 National ad international comparison
 It does not measure economic growth
 It measures the results of social economic and
political polices.
 The ultimate objective to attain a PQLA of 100

27. Human Development Index [HDI]
It consolidates three indicators [kil]
Knowledge (adult literacy rate and mean years of
schooling)
Income (real GNI per capita in purchasing power parity on US
dollars)
Life expectancy at age birth
To construct the index, fixed MINMUM and MAXIMUM
values have been established for each of these
indicators
 Life expectancy at birth: 25 years and 85years
 Adult literacy rate: Mean years of schooling
 Combined gross enrolment ratio: expected years of
schooling 0% and 100%
 Real GNI per capita(PPP$): 100 and 40,000(PPP$)

29. General formula
 Index = (Actual X1 Value) –(Minimum X1 Value)
(Maximum X1 Value) – (Minimum X1 Value)

31.  Ranking base:- Globally countries are divided in
the following four classes according to their score in
human development index –

32.  HDI is simple average o above three indices.
 Category HDI
 High human development category > 0.800
 Medium human development category b/w 0.500 to 0.799
 Low human development category < 0.500
 India comes in the medium human development category
ranking at no 132 131 Out of 188 countries 2017 0.624

34. Other Index
 Gender Related Development Index (GDI)
 Gender Empowerment Measure(GEM)
 Human Poverty Index (HPI)

35. Spectrumof disease
 It is a graphic representation of variations in the representations
of disease
 It is comparable to the spectrum of light where the colors may
vary from one end to the other

36. Spectrumof disease
DEATH
Severe sickness
Mild sickness
Unrecognised sickness
Freedom from sickness
Better heath
Postive health

37.  At one end of the disease spectrum are sub clinical infections which are
not ordinarily identified and at the other end are fatal illnesses
 These different manifestations are simply reflections of individuals
in different states of immunity and receptivity
 The sequence of events in the spectrum of disease can be interrupted
by early diagnosis and treatment or by preventive measures which if
introduced at a particular point will prevent or retard the further
development of the disease

38. DETERMINANTS OF HEALTH
*Health is multi factorial all the factors
which influence human health by their
interaction are termed determinants of
health.`

39. DETERMINANTS OF HEALTH

40. 1) BIOLOGICAL DETERMINANT
*Physical & mental traits of
every human being are to some
extent determined by nature of
his genes at moment of
conception & cannot be altered
after conception.
*Some diseases of genetic
origin
Down’s syndrome

41. 2) BEHAVIOURAL & SOCIO-CULTURAL
DETERMINANT :
*Lifestyle reflects whole range of
social values, attitudes & activities.
*Certain factors like: DRUG ADDICTS
LACK OF PHYSICAL ACTIVITIES
JUNK FOOD

42. They lead to major
diseases like:
*OBESITY
*DIABETES MELLITUS
*Coronary Heart Diseases
*LUNG CANCER

43. “Genes load the gun.
Lifestyle pulls the trigger”
Lifestyle Factors

44. 3. HEALTHY CHILD DEVELOPMENT
“A child’s development is influenced
greatly by their housing situation and
neighborhood, family earnings and level of
parental education, availability of nutritious
foods and physical activity, genetic
composition and access to medical and
dental services”
The early years of an individuals growth
shapes the development of the brain,
readiness for school, and determines

45. 4. HEALTH SERVICES
 It is paramount the a population has access to
services which are health promoting as well as
disease preventing in order to create a healthy
functioning community.
For example:
 *Effective ante-natal care
 *Immunization programmes
 *Primary health care services.
The principals of Primary Health Care: accessibility inter-
sectoral collaboration, appropriate technology, health
promotion, public participation

46. 5. SOCIAL ENVIRONMENTS
 It is important to the health of individuals to feel
a sense of support from the community at large.
 Gestures such as volunteering, personal
security, access to social support, participation
in community organizations, and charitable
donations help to bring a population together and
enhance health

47. 6. GENDER
Gender determines societal roles, personal characteristics, ways of
thinking and being, which are predetermined norms within any given
society.
There are many health related illness which relate to a gender biased
society.
Young men for example are more apt to commit suicide. Although
women live longer than their male counterparts, women are more
susceptible to depression as well as arthritis, which significantly
decreases their quality of life.
Gender issues also encompass dominion and patriarchy which still exist
within society, and how that governs the behaviors of some
individuals in various communities

48. 7. CULTURE
Marginalization is a significant challenge for
anyone who is outside of what is perceived
to be the dominant culture. This can be
detrimental to the future existence of various
cultures as cultural norms and even
languages can be lost due to stigmatization.
It is important to consider each aspect of a
culture in order to care for an individual or a
population in the most appropriate way
(Health Canada, 2003).

49. 8. INCOME & SOCIAL STATUS
•Income and social status are significantly linked to quality
of health. Those with more substantial incomes have
proportionately better and safer living
environments,access to higher education, and control over
their diet.
•Conversely, an income deficiency means an increased
struggle to get ahead and make life goals and decisions
as basic needs are hard to attain
•Therefore, families with a higher income have more
control over their lives and discretion in problem-solving
and decision-making.

50. 9. SOCIAL SUPPORT NETWORKS
 Family, friends and other means of
support are cornerstones for dealing
with life stressors and provide a means
of support.
 Infants, seniors and the range of
developmental stages in-between,
require varying amounts of support,
depending on age and life
circumstances.
 Meaningful relationships are emotionally

51. 10. EDUCATION & LITERACY
 Socioeconomic status is directly interlinked
with education.
 Sufficient childhood education as well as
continued life long learning initiatives for
adults provide a sense of purpose.
 In addition, education is paramount to
obtaining an adequate income and promotes
problem-solving capabilities.

52. 11. EMPLOYMENT AND WORKING
CONDITIONS
 It is said that those who have a feeling of control
within their place of work tend to live more enriched,
less stressful lives.
 Unemployed persons consequently lack a feeling of
stability and often fear for their livelihood as the may
not meet be capable of meeting the basic needs of
survival.
 Workplace stress can ultimately put a strain on family
relationships due to the individuals compromised well-
being.

53. 12. ENVIRONMENTAL DETERMINANTS
*Hippocrates was the 1st
person to relate disease
with environment.
*It is established fact that
environment has a direct
effect on the physical,
mental & social well being.

54. ENVIRONMENT
INTERNAL EXTERNAL
(Includes every
tissue , organ &
organ system.)
(All that which
is external to
human host.)
Elements such as healthy air quality, safety of drinking water, regulations on
food, and composition of soil are all factors that are taken for granted but vital
to the health and well-being of a population.

55. Ecology of health
 Ecology is defined as the science of mutual
relationship between living organisms and their
environment .
 The human ecosystem includes in addition to the
natural environment all dimensions of man-made
environment like physical chemical biological
psychological ( in short our culture and its products).
 Health, according to ecological concept, is visualized
as a state of dynamic equilibrium between man and
his environment.
 Examples : urbanization, industrialization,
deforestation land reclamation, construction of
irrigation canals dams etc.

56. Right to health
 1948 the universal declaration of human rights
established a breakthrough by stating in ARTICLE
25
 “Everyone Has The Right To A Standard Of Living
Adequate For The Health And Well – Being Of
Himself And His Family..”
 WHO also affirms it as one of the fundamental rights
of every human being

57. Right to health
 Right to medical care
 Right to responsibility for health
 Right to healthy environment
 Right to food
 Right to procreate (artificial insemination)
 Right to not to procreate (family planning,
sterilization and legal abortion)
 Right to the deceased persons ( determination of
death, autopsies, organ removal)
 Right to die ( suicide, hunger strike, discontinuation
of life support measures ) ….
When resources are limited as in developing countries Govt. can give equal
right to available health care services

58. Responsibility for health
 Health is on one hand a highly personal
responsibility and on other hand a major public
health concern.
 Individual responsibility
 Community responsibility
 State responsibility
 International responsibility

59. 1. Individual responsibility
 Self care in health
 It is defined as “ those health generating activities
that are undertaken by the persons themselves”
It refers to activities individual undertakes in
 Promoting their own health
 Preventing their own disease
 Limiting their own illness
 Restoring their own health

60. 2. Community responsibility
Health care for the people to health care by
the people
Community participation can be
By providing facilities manpower, logistic support
and possibly funds
By involving in planning, management and
evaluation
 By joining in using the health services.

61. 3. State responsibility
 The Directive Principles of State Policy states the

62. 4. International responsibility
 Health for all
 MDGs
 SDGs

63. HEALTH & ITS
INDICATORS

64.  Health cannot be measured in exact measurable
forms.
 Hence measurement have been framed in terms of
illness (or lack of health), consequences of ill-health
(morbidity, mortality) & economic, occupation &
domestic factors that promote ill health- all the
antithesis of health.

65. INDICATORS OF HEALTH
 Indicator also termed as Index or Variable is only an
indication of a given situation or a reflection of that
situation.
 • Health Indicator is a variable, susceptible to direct
measurement, that reflects the state of health of persons in
a community.
 • Indicators help to measure the extent to which the
objectives and targets of a programme are being attained.
 • Numerical indication of the health of a given population
derived from a specified composite formula.

66. CHARACTERISTICS : IDEAL INDICATOR
 Should be valid. They should actually measure
what they are supposed to measure
 Should be reliable and objective. The answer
should be same if measured by different people in
similar situation.
 Should be sensitive. They should be sensitive
to changes in situation concerned
 Should be specific. They should reflect changes
only in situation concerned.
 Should be feasible. They should have the ability
to obtain data needed
 Should be relevant. They should contribute to
the phenomenon of interest

67. USES OF INDICATORS OF HEALTH
 Measurement of the health of the community.
 Description of the health of the community.
 Comparison of the health of different communities.
 Identification of health needs and prioritizing them.
 Evaluation of health services.
 Planning and allocation of health resources.
 Measurement of health successes

68. Indicators of Health

69. MORTALITY INDICATORS1. Crude death rate. The number of deaths per 1000 population
per year in a given community.
2. Expectation of life. The average number of years that will be
lived by those born alive into a population if the current age specific
mortality rates persist.
3. Infant mortality rate-sensitive. Is the ratio of deaths under 1 year of
age in a given year to the total number of live births in the same year;
usually expressed as a rate per 1000 live births
4. Child mortality rate.
5. Under – 5 proportionate
mortality rate
6. Maternal Mortality rate
7. Disease specific
mortality rate
8. Proportional mortality
rate

70. INFANT MORTALITY RATE
No of deaths of children less than 1 year of age in a
given year x 1000
No Of Life Births In Same Year
 Sensitive indicator of availability, utilization & effectiveness of
health care, particularly perinatal and postnatal care.
 Current IMR :India- 40/1000live birth
CAUSES OF INFANT MORTALITYNeonatal Mortality
(0-4 weeks)
1. Low birth weight and
prematurity
2. Birth injury and difficult labour
3. Sepsis
4. Congenital anomalies
5. Haemolytic diseases of
Post natal mortality rate
(1-12months )
1. Diarrhoeal disease
2. Acute Respiratory
infections
3. Other Communicable
diseases
4. Malnutrition

71. DEVELOPED COUNTRIES
Accidents
Congenital anomalies
Malignant neoplasms
Influenza,
Pneumonia.
Child mortality rate
The number of deaths at 1-4 yrs in a given year per 1000
children in that age group at the mid point of the year
concerned
No of deaths of children aged 1-4 years during a year x
1000
Total no of children aged 1-4 years at the middle of the
year
 CAUSES: Correlates with inadequate MCH services,
malnutrition, low immunization coverage and environmental
factors
DEVELOPING COUNTRIES
 Diarrhoeal diseases
 Respiratory Infections
 Malnutrition
 Infectious disease (e.g.,
measles, Whooping cough)

72. Under 5 proportionality rate
 It is the proportion of total deaths occurring in the
under- 5 age group
 It can be used to reelect both infant and child
mortality


73. Maternal mortality rate
Total No female deaths due to complications of
pregnancy, child birth or within 42 days of
delivery from puerperal cause in an area during
a given year to
Total no of live births in the same area & year
o SEVERE BLEEDING - 25%
o Infection - 15%
o Eclampsia - 08%
o Obstructed labour - 08%
o Unsafe abortion - 13%
o Direct causes - 08%
o Indirect causes - 20%
Causes :-
x 1000

74. MORBIDITY INDICATORS
It includes :
 Incidence & prevalence
 Notification rates
 Attendance rates at out-patient
departments.
 Health centers etc.,
 Admission, readmission and discharge
rates
 Duration of stay in hospital and

75. MORBIDITY :
A) Incidence & prevalence:
#Incidence = No. of new cases of specific
disease in given time
Total pop. at risk
X 1000
# Prevalence= No. of all old & new cases of
specific disease in given time
Estimated pop. In the
Same given time
X 100

76. Morbidity Indicators
 1. Notification rate
 2. Attendance rates at OPDs and at health centers.
 3. Admission, Readmission and discharge rates.
 4. Duration of stay in hospital
 5. Spells of sickness or absence from work or school.

77. DISABILITY RATES
EVENT-TYPE INDICATORS :
 Number of days of
restricted
activity
 Bed disability days
 Work-loss days
(or school loss days)
within a specified
period
PERSON – TYPE INDICATORS:
 Limitation of mobility:
For example, confined to bed, confined
to the house, special aid in getting
around either inside or outside the
house.
 Limitation of activity:
Limitation to perform the basic activates of
daily living (ADL)e.g., eating, washing,
dressing, going to toilet, moving about etc.,
Limitation in major activity,
e.g., ability to work at a job, ability to housework,

78. DISABILITY RATES
 SULLIVAN’S INDEX refers to
“Expectation of life free of disability”.
 • Sullivan’s Index = life expectancy of the
country -probable duration of bed
disability and inability to perform major
activities.
 • It is considered as one of the most
advanced indicators currently available.

79. DISABILITY RATES
 HALE is Health Adjusted Life Expectancy.
 Based on the framework of WHO’s ICIDH
(International Classification of Impairments,
Disabilities, and Handicaps )
 • Based on life expectancy at birth but includes
an adjustment for time spent in poor health.
 • It is the equivalent number of years in full
health that a newborn can expect to live based
on current rates of ill-health and mortality.

80. DISABILITY RATES
 DALYs: Disability Adjusted Life Years.
 It is defined as the number of years of
healthy life lost due to all causes whether
from premature mortality or disability.
 It is the simplest and the most commonly
used measure to find the burden of illness
in a defined population and the
effectiveness of the interventions

82. DISABILITY RATES
Uses of DALYs
 To assist in selecting health service priorities.
 To identify the disadvantaged groups.
 Targeting health interventions.
 Measuring the results of health interventions.
 Providing comparable measures for planning &
evaluating programmes.
 To compare the health status of different countries.
One DALY is one lost year of healthy life

83. DISABILITY RATES
 QALY is Quality Adjusted Life Year.
 It is the most commonly used to measure the
cost effectiveness of health interventions .
 It estimates the number of years of life added
by a successful treatment or adjustment for
quality of life.
 Each year in perfect health is assigned a value
of 1.0 down to a value of 0.0 for death.

84. NUTRITIONAL STATUS INDICATORS
This is a positive health indicator.
They are :-
 Anthropometric measurements of
preschool children
 Height
 Prevalence of low birth weight
 Vitamin A supplementation coverage
etc

85. HEALTH CARE DELIVERY INDICATORS
The frequently used indicators of health care delivery are:
1. Doctor – Population ratio [R:1/600] [ A: 1/2000]
2. Doctor – nurse ratio [R 1/5000]
3. Population – bed ratio [3.5/1000(.5)]
4. Population per health / Sub-centre [1/5000]
5. Population per traditional birth attendant [1/1000]

86. UTILISATION RATES
 Proportion of infants who are fully immunized against 6 EPI
diseases.
 Proportion of pregnant women's who receive ANC or have
their deliveries supervised by TBA.
 Percentage of population using the various methods of family
planning .
 Bed occupancy rate .
 Average length of the stay.
 Bed turn over ratio.

87. Suicide 10/100,000
Homicide
Road traffic accidents
Alcohol and drug abuse .
Smoking
Indicators of
social and mental health

88. ENVIRONMENTAL INDICATORS
 Air pollution .
 Water pollution.
 Radiation hazards .
 Solid wastes .
 Noise .
 Exposure to toxic substances in

89. Socio – economic indicators
 . Rate of population increase .
 Per capita GNP.
 Level of unemployment.
 Dependency ratio.
 Literacy rates.
 Family size.
 Housing .
 Per capita calorie availability

90. Health policy indicators
Proportion of GDP spent on health services.
Proportion of GDP spent on health related
services .
Proportion of total health resources devoted
to PHC.
 China spends 3 percent of its GDP on healthcare, the global
average is 5.4 percent of GDP.
 But the India spends only 1.2 percent of the GDP on the
healthcare sector.
 According to the World Health Organisation (WHO), India is at 112
position out of 170 countries in terms of its healthcare systems.

91. Indicators of quality of life
 It is difficult to define and even more
difficult to measure .
 It is subjective component of well being.
 Quality of life eg PQLI, HDI etc

92. Other indicators
 Social indicators .
 Basic needs indicator.
 Health for all indicators.
 Millennium Development Goal
indicators.

94. Concept of Disease

95. Concept of Disease
 “A condition in which body function is
IMPAIRED, DEPARTURE from a state of health,
an alteration of the human body interrupting
the performance of the vital functions.” - Webster.
 Oxford English Dictionary – The condition of body or
some part of organ of body in which its
functions are disrupted or deranged.
 Ecologically – ‘A maladjustment of human
organism to the environment’
 Simplest definition – ‘Opposite to Health’.

96. Historical Theories for
causation of disease
 “Supernatural causes”& Karma
 Theory of humors (humor means fluid)
 The miasmatic theory of disease
 Theory of contagion
 Germ theory
 Epidemiological Triad
 Multi-factorial causation
 Web of causation
………Supernatural to multi-factorial causes…
Environment
Agent Host

97. CONCEPT OF CAUSATION
Theories of causation of disease:
 Miasma theory: ‘ hippocratic school’
Miasma was “composed of malodorous &
poisonous substances generated by the
decomposition of organic matter” and was the
cause of disease.
 Germ theory of disease:
The concept of cause embodied here is referred
to as the ONE-TO-ONE relationship between
agent and disease

98. Epidemiological triad
Host, agent and environment interact with each other to
cause a disease or health condition.

100. Non communicable diseases???

101. Web of causation

102. Changes in life style stress
smoking
Lack of
physical
exercise
Abundance
Of food
Emotional
disturbances
Obesity Hypertension
Hyperlipidemia
Coronary atherosclerosis
Increased thrombosis
Changes in
Arterial wall
Coronary occlusion
Myocardial ischemia
Myocardial infarction
RISK FACTORS
IN MI

104. PREPATHOGENESIS PHASE
This refers to the period before the onset of disease in man.
The disease agent has not yet entered man, but the factors
which favors its interaction with the human host are already
existing in the environment.
The causative factors of disease may be classified as AGENT,
HOST and ENVIRONMENT, <epidemiological triad> and an
interaction of these three factors is required to initiate the
disease in man.

105. Agent factors
Definition
The disease agent is defined as a factor that
causes or contributes to a health
problem or condition.
1.Biological agents: These are the living agents
of disease, these exhibit host related properties
such as:
a. Infectivity
b. Pathogenicity
c. Virulence

106. 2. Nutrient agents: Any excess or deficiency of
the intake of nutritive elements, may result in
nutritional disorders.
Eg. PEM, Goitre, Obesity, vitamin deficiencies.
3. Physical agents: Excessive heat, cold,
humidity, pressure, radiation etc may result in
illness

107. 4. Chemical agents:
i) Endogenous: eg, urea(uremia),
serum bilirubin(jaundice),
ketones(ketosis) etc
ii) Exogenous: eg. Allergen, metals,
fumes,dust etc..
5. Mechanical agents:
to chronic friction and other
mechanical forces

108. 6. Absence or insuffiency or excess of a
factor necessary to health:
i) Chemical factors
ii) Nutrients factors
iii) Lack of structure
iv) Chromosomal factors
v) Immunological factors

109. 7. Social agents:
 Poverty,
 Smoking,
 Abuse of drugs and
alcohol,
 Social isolation ,
 Maternal deprivation
etc

110. The host is a susceptible human or animal who harbours and
nourishes a disease-causing agent.

111. Host factors :
i) Demographic factors
ii) Biological
characteristics
iii) Social and economic
characteristics
iv) Lifestyle factors

112. The external or macro-environment is defined as “all that which is
external to the human host, living or non-living, and with which
he is in constant interaction.”

113. The environment of man is divided
into 3 components:
i) Physical environment:
Is applied to all non-living things and physical factors( e.g.
air, water, soil etc.) with which man is in constant
interation.
In most of the developing countries
defective environment continues to the main
Health problems :
Air & water pollution, urbanization,
radiation hazards, lack of sanitation
etc

114. ii) Biological environment:
 It is the universe of living
things which surrounds man
including man himself
 Disease producing agents,
reservoirs of infections,
intermediate hosts and
vectors of disease.

115. : iii) Psychosocial environment
 “Those factors affecting personal
health, health care and community
well-being that stem from the
psychosocial make-up of individuals
and the structure and functions of
social groups.”
 Like: cultural values, customs,
habits, morals, religion, lifestyles etc

116. a risk factor?
 The term “RISK FACTOR” has 2 meanings
1. An attribute or exposure that is significantly
associated with the development of a disease.
2. A determinant that can be modified by intervention,
thereby reducing the possibility of occurrence of
disease or other specified outcomes.

117. Why are risk factors important?
Today’s risk factors are
indicative of
tomorrow's diseases


118. CHARACTERISTICS OF RISK
FACTORS
 Preventable
 Modifiable
 Measurable
 Feasible to monitor
 Provide vital information for health planning
and management
 Increasing in developing world
 Preventing and reducing them in individuals and
populations must lead to:
 decrease in future NCD burden
 improve quality of life

119. Classification of Risk Factors
 Non Modifiable
RF
 Age
 Sex
 Genetic
 Behavioral RF
 Tobacco Use
 Alcohol Use
 Physical
Inactivity
 Diet
Intermediate RF
 Obesity
 Hypertension
 Diabetes
 Lipid
abnormality

120. Risk groups
 An approach developed by WHO is to identify
precisely the ‘risk groups’ or ‘target groups’ (eg, at-
risk mothers, at-risk infants, at-risk families, chronically ill, handicapped,
elderly)in the population by certain defined criteria
and direct appropriate action to them first.
 This is known as the ‘RISK APPROACH’
 To sum up ‘something for all, but more or those in need- in
proportion to the need’
 It is a managerial device for increasing the efficiency
of health care services within the limits of existing
resources

122. Guidelines for defining‘at-risk’groups
a)Biological situation:
-Age group
-Sex
-Physiological state
-Genetic factors
-Other health conditions
b) Physical situation:
-Rural, urban slums
-Living conditions, overcrowding
-Environment, water supply
c)Social and cultural situation:
-Social class
-Ethnic & cultural group
-Family disruption, education , behavior
-Customs, habits, lifestyles, attitudes
-Access to health services

123. Pathogenesisphase
 The pathogenesis phase begins with the entry of the
disease ‘agent’ in the susceptible human host.
 The disease agent resides, multiplies and induces
tissue and physiological changes and later through
early and late pathogenesis which forms a clear-cut
infectious diseases.

124.  The final outcome of the disease may be
RECOVERY, DISABILITY or DEATH
• At this stage the host’s reaction to the
disease may be CLINICAL or SUBCLINICAL; TYPICAL or
ATYPICALor the host may become carrier.

125.  In chronic diseases like HTN ,
CHD , early pathogenesis
doesn’t show any symptoms of
the disease.
 The clinical stage begins when
host shows signs and
symptoms, by this time the
disease phase is already well
advanced into late
pathogenesis.

126. Iceberg phenomenon of disease

127. Eg: POLIOMYELITIS AND HYPERTENSION

128.  According to this , disease in a community is compared to
the iceberg
 The floating tip of the iceberg represents what the
physician sees i.e. the clinical cases. The vast submerged
portion represents the hidden mass of disease i.e. the
latent, in-apparent, pre--symptomatic and undiagnosed
cases and carriers in the community
 The water line represents the demarcation between
apparent and in-apparent disease

129.  But there are no methods for detection of sub clinical
states due to which many diseases are detected when the
signs and symptoms appear in the susceptible host. i.e. in
the pathogenesis phase
•The hidden part of the iceberg thus constitutes
an important undiagnosed reservoir in the
community and its detection and control is a
challenge to modern techniques in preventive
medicine

130. THANKYOU