Concepts of health and disease

Concepts of Health & Disease
Ms. NAMITA BATRA GUIN
Associate Professor, Community Health
Nursing Dept.

Lecture Objectives
 At the end of lecture students are expected to:
 To define the terms : Health and disease.
 To describe general factors affecting health
 To discuss various dimensions of heath
 To explain the indicators of health.
 To describe the concepts of causation of disease, concepts
of control and concept of prevention

Concept of Health
 Health is the common theme in almost all the
countries.
 Absence of diseases = Health
 Health = Harmony = being in peace with self,
community, god and cosmos,
 Body equilibrium with the humors.

Historical background
 Health was neglected after WW1 in the League of
Nation, added later.
 Same happened after WW2 in the United Nation
Charter. Later W.H.O was for established and
constitution approved in 1948.
 1977 The 30th World Health Assembly” the
attainment by all citizens of the world by the year
2000 of a level of health that will permit them to lead
a socially and economically productive life” HFA/2000
( Health For All by Year 2000)
 1979 UN “Health is an Integral part of the Socio-
economic Development plans”.

Defining Health:
 1- The WHO Definition
 Health is the complete of status of physical, mental and social well-
being and not only the absence of disease or infirmity
A Healthy Person is “ leading a socially and economically active
live"
 2- Health is the presence of a positive capacity to lead energetic
satisfying and productive life.
 Operational definition of health:
A condition or quality of the human organism expressing the adequate
functioning of the organism in given conditions, genetic or
environmental.
3 -Ecological definition:
“health is a state of optimal physical, mental and social
adaptation to one’s environment.”
 Health is a relative, not an absolute concept-always involves
many levels or degrees

Changing Concepts of Health
 Biomedical : “ health is the absence of disease”-
Germ theory of disease. Concept viewed man as
machine, and disease as consequence of
breakdown of the machine.
 Minimized the role of : Environmental, Social
Psychological, Economic, Cultural and other
determinants.
 Germ theory could not solve : Nutritional,
Chronic diseases, Accidents, Substance abuse,
Psychological diseases, pollution, population
explosion and other health non communicable
health problems.

 Ecological Concept:
 Health is an Dynamic Equilibrium between Man
and his Environment. Imbalance results in
Disease.
 ( Imperfect man and Imperfect Environment)
 ** Adaptation of Man to his Environment leads
to better health and longer life expectancy even
in the absence of Modern health services.

 Psychosocial concept
 Biomedical ( Biological) in addition to:
Psychological, Social, Cultural , Economic,
Political factors
 Holistic concept:
 Include all the factors of the other concepts in
addition to all human activities such education,
communication, agriculture, industry, housing ,
recreation etc.
 Emphasis on Promotion and Protection of Health

Definition of Health
 Health is a state of complete physical, mental
and social wellbeing and not merely an absence
of disease or infirmity.
 The definition has been amplified and has
included the ability to lead a socially and
economically productive life.

Health-sickness spectrum
 There are degrees or levels of health as
there are degrees or severity of illness.

Health-sickness spectrum
 Health and disease lie on a continuum and
there is no single cut-off point.
 Health fluctuates within a range of
optimum well-being to various levels of
dysfunction.
 The transition is often gradual.
 This concept emphasizes that health is not
static, and is a dynamic phenomenon, a
process of continuous change, subject to
frequent variations.

New philosophy of Health
*Fundamental right
*Interesctorial
*Integral part of Development
*Central to Quality of Life
*Involves Individuals, Families, Communities
Local, National and International
responsibilities
*Social Investment
*World wide Social Goal.

Dimensions of Health
 1- Physical dimension:
Physical health means perfect functioning of the body. All the
organs of the body are of average size and function normally;
all the special senses are intact; the resting pulse rate, BP and
exercise tolerance are all within the range of normality for the
individual’s age and sex.
Genetic make-up, age, developmental level, race and sex are all
part of an individual’s physical dimension
Signs of physical health in an individual are: a good complexion,
clean skin, bright eyes, lusturous hair with a body well clothed
with firm flesh, good appetite, sound sleep etc..

 2-Mental dimension
Defined as the state of balance between the
individual and the surrounding world, a state
of harmony between oneself and others.
Psychological factors can induce all kinds of
illness, not simply mental ones. Long –term
stress affects the body systems; conversely,
calm and relaxation can actually change the
body response to illness.

Mental dimension (cont.)
The following characteristics are attributes of a
mentally healthy person: a) he is free from
internal conflicts, b) he accepts criticism, c)
he searches for identity, d) he has a strong
sense of self-esteem, e) he knows himself, f)
he has a good self-control, g) he faces
problems and tries to solve them.

 3-Social and economic dimensions
Social well-being implies harmony and integration
within the individual, between each individual and
other members of the society and between
individuals and the world in which they live.
Health practices and beliefs are strongly influenced
by a person’s economic level, life style, family and
culture. Low-income groups are less likely to seek
health care to prevent or treat illness; high-income
groups are more prone to stress-related habits and
illness

 3-Social and economic dimensions
Social dimension include of health includes the levels of
social skills one possesses, social functioning and the
ability to see oneself as a member of a larger society.

 4-Spiritual dimension
Spiritual health refers to the part of individual that strives for the
meaning and purpose in life. It includes principles and ethics,
the purpose in life, religious beliefs and values; all are important
components of the way the person behaves in health and
illness.
 5-Vocational dimension
When work is fully adapted to human goals, work often plays a
role in promoting both physical and mental health. It is usually
associated with an improvement in physical capacity, while goal
achievement and self-realization are sources of satisfaction and
enhanced self esteem.
The importance of this dimension is exposed when individuals
suddenly lose their jobs or retire.

 6- Emotional dimension
Too closely related to mental dimension. But mental health can be seen as
“Knowing” or “Cognition” while emotional health relates to “feelings”.
 7- Other dimensions
 Cultural dimension
 Environmental
 Educational dimension
 Nutritional dimension
 Curative dimension
 Preventive dimension

Determinants of Health
 Health is multifactorial
 Many factors influence the health of an
individual.
 These factors interact and these interactions
may be health promoting or deleterious.
 Few of the determinants of health are:

 Biological: physical and mental traits of the
person depends upon the nature of the genes. A
number of diseases are of genetic origin. E.g.
Diabetes mellitus, anomalies, errors in
metabolism etc.
 Behavioural & socio-cultural: includes the
person’s behaviour and life long personal habits
(like smoking, alcoholism). Lifestyles are learnt
through social interactions with parents, peer
groups, friends, siblings and school and mass
media.

 Environment: classified as internal and
external. Environmental factors ranges from
housing, water supply, psychosocial stress and
family structure through social and economic
support systems to he organization of health and
social welfare services in the community.
 Socio-economic: for majority of the world
health status is determined by the socio-
economic development. It includes the factors
like: per capita GNP, education, nutrition,
employment, housing political system etc.

 Health Services: It covers the wide variety
spectrum of personal and community services
for treatment of disease, prevention of illness
and promotion of health. e.g. care of pregnant
mother can reduce maternal and infant
mortality.
 Aging of population: major concern of rapid
population aging is increased prevalence of
chronic diseases and disabilities both being
conditions

 Gender: women’s health issues affects the
overall health of the community. It includes
nutrition, reproductive health, lifestyle,
occupational environament etc.
 Others: Human rights, equity and social justice,
infromation and communition etc.

Indicators of Health
 Indicator means reflection of a given situation.
 A Health indicator is a characteristic of an individual,
population, or environment which is subject to
measurement (directly or indirectly) and can be used to
describe one or more aspects of the health of an
individual or population (quality, quantity and time).
 Purposes:
 Measures the health status
 To make comparisons
 To assess the health care needs
 For monitoring and evaluation

 Characteristics of an Ideal indicator
 Valid
 Reliable
 Sensitive
 Specific
 Feasible
 Relevant

 Following are the indicators
 Mortality indicators
 Morbidity indicators
 Disability indicators
 Nutritional status indicators
 Health care delivery indicators
 Utilization rates
 Indicators of social and mental health
 Environmental indicators
 Socio-economic indicators
 Health policy indicators
 Indicators of quality of life
 Other indicators

 Mortality indicators
 Crude death rate: defined as the no. of deaths per 1000
population per year in a given community. Its not a perfect
indicator of health status, but decrease in death provides an
indirect measure of overall health improvement.
 Expectancy of life: life expectancy at birth is the average no.
of years that will be lived by those born alive into population if
current age-specific mortality rates persists. It is influenced by
the infant mortality rate. It is a good indicator of socio-
economic development of a nation. It is a positive health
indicator.
 Infant mortality rate: it is the ratio of deaths under 1 year of
age in a given year to the total no. of live births in the same
year. Usually accepted indicator of health. It is the most sensitive
indicator of availability, utilization and effectiveness of health
care.
 Other: U5MR, disease specific mortality rate, MMR etc.

 Morbidity indicators
 Incidence and prevalence
 Notification rates
 Attendance rates at OPD, health centers.
 Duration of stay at hospital
 Spells of sickness or absence from work or school
These rates are used to supplement the mortality data to describe
the health status of a population. Subclinical and inapparent
conditions are not included in these indicators.

 Disability indicators
 Event type indicators
 No. of days of restricted activity
 Bed disability days
 Work loss days
 Person type indicators
 Limitation of mobility: e.g. confined to bed, house etc.
 Limitation to activity: e.g. limitation to perform the basic activities of
daily living (ADL).
Sullivan’s index: it is expectation of life free of disability. Life expectancy –
probable duration of bed disability or inability to perform activity.
HALE (Health – Adjusted Life Expectancy): measures healthy life
expectancy. It is based on life expectancy at birth but includes an
adjustment of time spent in poor health.
DALE (Disability – Adjusted Life Years): measure of burden of disease in
a defined population and the effectiveness of the interventions. ONE DALY
IS “ONE LOST YEAR OF HEALTHY LIFE”

 Nutritional indicators
 A positive health indicator. The important indicators are:
 Anthropometric measurements of preschool children
 Heights of children at the school entry
 Prevalence of low birth weight

 Health care delivery indicators
 Doctor – population ratio
 Doctor – nurse ratio
 Population – bed ratio
 Population per health/subcenter
 Population per TBA
These indicators reflects the equity of distribution of health
resources in different parts of the country and the provision of
health care.

 Utilization rates
 Expressed as the proportion of people in need of the service who
actually receive it in a given period of time.
 It get affected by the availability and accessibility of health
services and attitude of an individual towards health and health
care system
 Proportion of infants who are fully immunized against 6
VPD’s
 Proportion of pregnant women who receive ANC or have
deliveries supervised by a trained personnel
 Percentage of population using the various methods of
family planning
 Bed-occupancy rates
 Average length of stay

 Indicators of social and mental health
 Suicide
 Homicides in community
 Acts of violence
 Road traffic accidents
 Juvenile delinquency
 Alcohol and drug abuse cases
 Family violence
 Battered baby syndrome
 Neglected and abandoned youths

 Environmental indicators
 Reflect the quality of physical and biological environment in
which disease occur and people live.
 Air and water pollution related indicators
 Radiation indicators
 Solid waste indicators
 Noise pollution related indicators
 Proportion of population having access to safe drinking water
and sanitation facilities

 Socio-economic indicators
 Rate of population increase
 Per capita GNP
 Level of employment
 Dependency ratio
 Literacy rates
 Family size
 Housing: no. of persons per room
 Per capita calorie availability

 Health policy indicators
 Gives the account of the political commitment of
allocation of adequate services.
 Proportion of GNP spent on health services
 Proportion of GNP spent on health related activities
 Proportion of total health resources devoted to primary health
care

 Indicators of quality of life
 Quality of life is difficult to define and difficult to measure.
 It can be assessed by the person’s subjective feeling of
happiness or unhappiness about various life concerns
 PQLI: Physical Quality of Life Index- it includes 3 indicators:
IMR, life expectancy at age one and literacy.
 It is represented on the scale of 0 to 100. where 0 represents
worst performance and 100 as best performance.
 It does not measure economic growth.
 HDI: Human Development Index- A composite index
combining indicators representing 3 dimensions: life expectancy
at birth (Longevity); Adult literacy rate and mean years of
schooling (Knowledge) and real GDP per capita (Income).
 Values ranges between 0 to 1.
 Iceland, Norway and Australia tops the charts in HDI; while
countries like Niger, Sierra leone are at the bottom positions.

 Other indicators
 Social indicators: families and households, learning and
educational services, consumption and accumulation, social
security and welfare services, health services and nutrition,
housing and its environment etc.
 Basic need indicators: calorie consumption, access to water,
life expectancy, death due to disease, illiteracy, rooms per
person, GNP per capita.
 Health for all indicators: resource allocation, political
commitment, income distribution, food availability, adult literacy
rate etc.
 Millennium development Goals indicator: under five
mortality rates, maternal mortality ratio, proportion of births
attended by the skilled health personnel, HIV prevalence among
young people aged 15-24years etc.

Definition of disease, illness, and
sickness
 The Oxford English Dictionary defines disease
as “a condition of the body or some part or
organ of the body in which its functions are
disrupted or deranged”.
 From an ecological point of view, disease is
defined as “a maladjustment of the human
organism to the environment”.
 The WHO has defined health but not disease.

sickness
 Disease, illness, and sickness are not
synonymous. The term disease literally means
without ease, the opposite of ease-when
something is wrong with bodily function.(
Professional definition based on a
pathological process- OBJECTIVE)
 Illness refers to the individual’s perceptions
and behavior in response to being ill ( loss of
function , not feeling well- SUBJECTIVE)
 Sickness refers to a state of social
dysfunction.( from disease or illness)

sickness
 Disease : physiological/ psychological
dysfunction defined professionally.
 Illness: Subjective state of person who feels
aware of not being well.
 Sickness: State of social dysfunction based on
professional and social agreement.

Concepts of causation of disease
 GERM THEORY OF DISEASE
 The disease is caused by microbes.
 Shows one to one relationship between causal
agent and disease.
 Disease agent Man Disease
 However, disease causation depends upon various
factors.

 EPIDEMIOLOGICAL TRIAD
 It stressed upon three factors responsible for
causation of any disease i.e. : host, agent and
environment.
Environment
Agent Host

 MULTIFACTORIAL CAUSATION
 Diseases like lung cancer, CAD, chronic bronchitis
etc. could not be explained on the basis of germ
theory.
 It lead to the realization that there are other
factors in aetiology of disease
 Diseases like CAD can be because of multiple
factors

 WEB OF CAUSATION
 Model was given by MacMahon and Pugh.
 Ideally suited for chronic disease, where disease
agent is not known, but the outcome is outcome
of interactions of multiple factors.
 Considers all predisposing factors of any type and
their complex interrelationship with each other.
 Sometimes the removal of any one of the link may
be sufficient to control the disease.

Natural History of disease
 Signifies the way in which a disease evolves
over time from the earliest stage of its
prepathogenesis phase to its termination as
recovery, diasbility or death, in the absence of
treatment or prevention.
 It is not same for all diseases, or in all
individuals.
 It has two phases: prepathogenesis- process
in environment and pathogenesis- process in
man.

 Prepathogenesis phase:
 Refers to the period of preliminary to the onset of
disease in man.
 Disease agent has not yet entered man, but
factors favoring are present in the environment.
 It is referred to as man exposed to risk of the
disease.
 Causative factors are referred to as
epidemiological triad.
 Interaction between all the factors is necessary to
cause a disease in man.

 Pathogenesis phase:
 Begins with the entry of disease agent in the
susceptible human host.
 Disease agent multiplies and induces tissue and
physiological changes.
 Final outcome of the disease may be recovery,
disability or death.
 This phase can be modified with the interventions
like: immunization and chemotherapy.
 Infection may be clinical or subclinical.
 In chronic diseases this phase is known as
presymptomatic phase.

 Agent factors:
 Defined as substance, living or non-living, or a force,
tangible or intangible, the excessive presence or absence of
which may initiate or perpetuate a disease process.
 Can be single or multiple in number.
 Can be classified as:
 Biological agents: (Infectivity, pathogenicity and virulence)
 Nutrient agents
 Physical agents
 Chemical agents- endogenous and exogenous
 Mechanical agents- tearing, sprains etc.
 Social agents- poverty, alcohol etc.
 Absence or insufficiency or excess of a factor necessary to
health- chemical factor (hormones), lack of structure (thymus),
lack of part of structure (cardiac defects), chromosomal factors
(turner’s syndrome), immunological
factors(agammaglobulinaemia), nutritional factors.

 Host factors (Intrinsic)
 Demographic characteristics – age, sex etc
 Biological characteristics- genetic factors,
biochemical levels of blood, physiological
functioning of organs
 Socio-economic characteristics- education,
occupation, stress, marital status.
 Lifestyle factors- personality traits, living habits,
nutrition, physical exercise etc.

 Environmental factors (Extrinsic)
 All that is external to the individual human
host, living and non-living and which he is in
constant interaction.
 Physical environment- air, water, soil, housing radiation etc.
 Biological environment- rodents, animals, plants, microbes,
insects etc.
 Psychological environment- cultural values, customs, habits,
beliefs, attitudes, morals, religion, education etc.

Disease Cycle
 Course of most of the communicable diseases
is marked by various stages.
 Stages are:
 Incubation period: time interval between the
entry of the disease agent in the body and
manifestations of the clinical signs and symptoms.
 Prodromal period: short period ranging from 1-
4days and is marked by the vague S/S. clinical
diagnosis is not possible.
 Fastigium: represents the height of the disease.
S/S are clear cut. Pt. is confined to bed. Clinical
diagnosis is possible.

Disease Cycle
 Defervescence: pt. begins to feel better, the
body defences begin to respond.
 Convalescence: pt.’s recovery is established.
 Defection: the patient recovers from illness,
sometimes with defects/ disability.

Stages of illness behavior
 STAGE 1: SYMPTOM EXPERIENCE
The person is aware that "something is
wrong". A person usually recognizes
change such as pain, a rash or a
limitation in functioning but does not
suspect a specific diagnosis.

 STAGE 2 : ASSUMPTION OF THE SICK
ROLE
If symptoms persist and become severe, clients
assume the sick role. At this point the illness
becomes a social phenomenon, and sick
people seek confirmation from their families
and social groups that they are indeed ill and
that they be excused from normal duties and
role expectations.

 STAGE 3: MEDICAL CARE CONTACT
If symptoms persist despite the home
remedies, become severe, or require
emergency care, the person is
motivated to seek professional health
services.

 STAGE 4 : DEPENDENT CLIENT ROLE
The client depends on health care professionals for the
relief of symptoms. The client accepts care, sympathy
and protection. A client can adopt the dependent role
in a health care institution, at home, or in a
community setting. The client must also adjust to the
disruption of a daily schedule.
 STAGE 5 : RECOVERY AND REHABILITATION
This stage can be full recovery . In the case of chronic
illness, the final stage may involve in an adjustment
to a prolonged reduction in health and functioning.

Iceberg of disease
 According to this concept, disease in the
community may be compared to an iceberg.
 The floating tip of which represents the sign
and symptoms visible to a physician. i.e.
clinical cases.
 The submerged portion represents the hidden
mass of disease. i.e. latent, inapparent, pre-
symptomatic and undiagnosed cases and
carriers in the community.

Levels of Prevention
 Primordial
 Prevention of the emergence or development of
risk factors in countries or population groups in
which they have not appeared
 Efforts are directed towards discouraging the
harmful lifestyles.
 Intervention is through individual and mass
education.

 Primary
 Action taken prior to the onset of disease which removes the
possibility that the disease will ever occur.
 Signifies intervention in the pre-pathogenesis phase of the
disease
 Health promotion and specific protection are the
interventions.
 Health promotion- process of enabling people to increase
control over, and to improve health. Includes- health
education, environmental modifications, nutritional
interventions, lifestyle/ behavioral changes.
 Specific protection- includes: immunization, use of specific
nutrients, chemoprophylaxis, protection against accidents,
protection against occupational hazards etc.

 Secondary
 Action which halts the progress of a disease at its
incipient stage and prevents complications.
 Interventions include- early diagnosis and early
treatment.
 The earlier is the diagnosis, the better is the
prognosis.

 Tertiary
 Signifies intervention in late pathogenesis phase.
 All measures available to reduce or limit
impairments and disabilities, minimize sufferings
caused by the existing departures from good
health and to promote the patient’s adjustment to
irremediable conditions.
 Interventions include- disability limitation and
rehabilitation
 Rehabilitation- combined and coordinated use of
medical, social, vocational, educational measures
for training and retraining the individual to the
highest possible level of functional ability

Concepts of Control
 Describes operations in reducing:
 Incidence of the disease
 Duration of the disease
 Effects of infection, including both physical and
psychological
 Financial burden to the community.

Concepts of Control
 Disease elimination- interruption in the
transmission of the disease.
 Disease eradication- termination of all
transmission of infection by the extermination
of the infectious agent.
 Smallpox is the only disease eradicated from
the world.

Concepts of Control
 Monitoring and evaluation
 Monitoring: performance and analysis of routine
measurements aimed at detecting changes in the
environment or health status of population.
 Refers to the ongoing measurement of the
performance of health services or a health
professional.
 Surveillance- continuous scrutiny of the factors
that determine the occurrences and distribution of
disease and other conditions of ill-health.
 Objectives- 1. provide information about the new
trends
 2. Provide feedback
 3. Provide timely warning of public health disasters

Concepts of Control
 Monitoring and evaluation
 Evaluation of control
 Process by which the results are compared with
the intended objectives.
 Crucial in identifying the health benefits derived
 Useful in identifying the performance difficulties
 Should be considered during planning and
implementation.

Concepts of health and disease

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