Prevention and levels of prevention of Community Medicine lecture .This lecture also has concepts of disease,surveillance, monitoring and iceberg phenonomenon of disease.

4.  The goals of medicine are to promote health, to
preserve
health, to restore health when it is impaired, and to
minimize
suffering and distress. These goals are embodied in the
word
"prevention" .
Successful prevention depends upon a knowledge of
causation, dynamics of transmission, identification of risk
factors and risk groups, availability of prophylactic or early
detection and treatment measures, an organization for
applying these measures to appropriate persons or groups,
and continuous evaluation of and development of
procedures applied

6.  Primordial prevention, a new concept, is
receiving special attention in the prevention of
chronic diseases.
 This is primary prevention in its purest sense,
that is, prevention of the emergence or
development of risk factors in countries or
population groups in which they have not yet
appeared.

7.  For example, many adult health problems (e.g.,
obesity, hypertension) have their early origins
in childhood, because this is the time when
lifestyles are formed (for example, smoking,
eating patterns, physical exercise).
 In primordial prevention, efforts are directed
towards discouraging children from adopting
harmful lifestyles. The main intervention in
primordial prevention is through individual
and mass education.

12.  The concept of primary prevention is now
being applied to the prevention of chronic
diseases such as coronary heart disease,
hypertension and cancer based on
elimination or modification of "risk-factors"
of disease.
 The WHO has recommended the following
approaches for the primary prevention of
chronic diseases where the risk factors are
established :
 a. population (mass) strategy
 b. high-risk strategy

15.  In summary, primary prevention is a "holistic"
approach.
 It relies on measures designed to promote health
or to protect against specific disease "agents" and
hazards in the environment. It utilizes knowledge
of the pre pathogenesis phase of disease,
embracing the agent, host and environment.
 Fundamental public health measures and
activities such as sanitation; infection control;
immunization; protection of food, milk, and water
supplies; environmental protection; and protection
against occupational hazards and accidents are all
basic to primary prevention

16.  Secondary prevention can be defined as "action
which halts the progress of a disease at its
incipient stage and prevent complications".
 secondary prevention attempts to arrest the
disease process; restore health by seeking out
unrecognized disease and treating it before
irreversible pathological changes have taken place;
and reverse communicability of infectious
diseases.

17. Secondary prevention is largely the domain of clinical
medicine. The health programmes initiated by
governments are usually at the level of secondary
prevention.
The drawback of secondary prevention is that the patient
has already been subject to mental anguish, physical pain;
and the community to loss of productivity. These
situations are not encountered in primary prevention.
Secondary prevention is an imperfect tool in the control
of transmission of disease.
It is often more expensive and less effective than primary
prevention

18.  Tertiary prevention can be defined as "all
measures available to reduce or limit
impairments and disabilities, minimize
suffering caused by existing departures from
good health and to promote the patient's
adjustment to irremediable conditions" .
 For example, treatment, even if undertaken late
in the natural history of disease may prevent
sequelae and limit disability. When defect and
disability are more or less stabilized, rehabilitation
may play a preventable role.

20.  "Intervention" can be defined as any attempt to
intervene or interrupt the usual sequence in the
development of disease in man.
 This may be by the provision of treatment,
education, help or social support.
 Five modes of intervention have been
described which form a continuum
corresponding to the natural history of any
disease

21.  1. Health promotion
 2. Specific protection
 3. Early diagnosis and treatment
 4. Disability limitation
 5. Rehabilitation

37.  MODES OF INTERVENTION-
Disability limitation
Rehabilitation

41. 1.Accident. ............ . Disease (or
disorder)
2.Loss of foot …………….. Impairment
(extrinsic or intrinsic)
3.Cannot walk………………Disability
(objectified)
4.Unemployed ...... ……Handicap
(socialized)

46.  There have been many attempts to define
disease.
 Webster defines disease as "a condition in
which body health is impaired, a departure
from a state of health, an alteration of the
human body interrupting the performance
of vital functions".

48.  The WHO has defined health but not disease. This is
because disease has many shades ("spectrum of disease")
ranging from inapparent (subclinical) cases to severe
manifest illness.
Some diseases commence acutely (e.g.,food poisoning),
and some insidiously (e.g., mental illness, rheumatoid
arthritis). In some diseases, a "carrier" state occurs in which
the individual remains outwardly healthy, and is able to
infect others (e.g., typhoid fever).
In some instances, the same organism may cause more
than one clinical manifestation (e.g., streptococcus). In
some cases,the same disease may be caused by more than
one organism (e.g., diarrhoea). Some diseases have a short
course, and some a prolonged course.

52.  1. Germ theory of disease
 2. Epidemiological triad
 3. Multifactorial causation
 4. Web of causation

53.  The concept of cause embodied in the germ theory
of disease is generally referred to as a
one-to-one relationship between causal agent and
disease.
The disease model accordingly is :
 Disease agent --- Man --- Disease
 It is now recognized that a disease is rarely caused
by a single agent alone, but rather depends upon a
number of factors which contribute to its
occurrence. Therefore, modern medicine has
moved away from the strict adherence to the germ
theory of disease.

56.  Agents of infectious diseases include bacteria,
viruses, parasites, fungi, and molds. With
regard to non-infectious disease, disability,
injury, or death, agents can include chemicals
from dietary foods, tobacco smoke, solvents,
radiation or heat, nutritional deficiencies, or
other substances, such as poison.
 One or several agents may contribute to an
illness.

62.  As a result of advances in public health,
chemotherapy, antibiotics and vector control
communicable diseases began to decline only
to be replaced by new types of diseases, the so-
called "modern" diseases of civilization, e.g.,
lung cancer,coronary heart disease, chronic
bronchitis, mental illness, etc.
These diseases could not be explained on the basis
of the germ theory of disease nor could they be
prevented by the traditional methods of isolation,
immunization or improvements in sanitation.

68.  Disease control-
 The term "disease control" describes (ongoing)
operations aimed at reducing:
 i. the incidence of disease
 ii. the duration of disease, and consequently
the risk of transmission
 iii. the effects of infection, including both the
physical
 and psychosocial complications; and
 iv. the financial burden to the community.

69.  Control activities may focus on primary
prevention or secondary prevention, most
control programmes combine the two. The
concept of tertiary prevention is comparatively
less relevant to control efforts

70.  Between control and eradication, an
intermediate goal has been described, called
"regional elimination" . The term "elimination"
is used to describe interruption of transmission
of disease, as for example, elimination of
measles, polio and diphtheria from large
geographic regions or areas . Regional
elimination is now seen as an important
precursor of eradication .

71.  Eradication literally means to "tear out by
roots".
 Eradication of disease implies termination of
all transmission of infection by extermination
of the infectious agent.
 Today, smallpox is the only disease that has
been eradicated globally.
 During recent years, three diseases have been
seriously advanced as candidates for global
eradication within the foreseeable future: polio,
measles and dracunculiasis.

73.  The disease "agent" is defined as 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.

74.  1. Biological agents
 2. Nutrient agents
 3. Physical agents
 4. Chemical agents
 5. Mechanical agents
 6. Absence or insufficiency or excess of a factor
necessary to health
 7. Social agents

75.  1. Biological agents-
 These are living agents of disease, viz, viruses, rickettsiae,
fungi, bacteria, protozoa and metazoa. These agents
exhibit certain "host-related" biological properties such as:
 (i) infectivity: this is the ability of an infectious agent to
invade and multiply (produce infection) in a host;
 (ii) pathogenicity: this is the ability to induce clinically
apparent illness, and
(iii) virulence: this is defined as the proportion of clinical cases
resulting in severe clinical manifestations (including
sequelae).
The case fatality rate is one way of measuring virulence

76.  2. Nutrient agents-
These are proteins, fats, carbohydrates,
vitamins,minerals and water. Any excess or
deficiency of the intake of nutritive elements may
result in nutritional disorders.
Protein energy malnutrition (PEM), anaemia,
goitre, obesity and vitamin deficiencies are some of
the current nutritional problems in many
countries.

77.  3. Physical agents-
 Exposure to excessive heat, cold, humidity, pressure, radiation, electricity,
sound, etc may result in illness.
 4. Chemical agents-
 (i) Endogenous: Some of the chemicals may be produced in the body as a
result of derangement of function, e.g., urea ureamia), serum bilirubin
(jaundice), ketones (ketosis), uric acid (gout), calcium carbonate (kidney
stones), etc.
 (ii) Exogenous: Agents arising outside of human host,
 e.g., allergens, metals, fumes, dust, gases, insecticides, etc.
 These may be acquired by inhalation, ingestion or inoculation.
 5. Mechanical agents-
 Exposure to chronic friction and other mechanical forces may result in
crushing, tearing, sprains, dislocations and even death.

78.  6. Absence or insufficiency or excess of a factor
necessary to health
 These may be (i) Chemical factors: e.g., hormones
(insulin, oestrogens, enzymes)
 (ii) Nutrient factors: given under no.(2)above
 (iii) Lack of structure: e.g., thymus
 (iv) Lack of part of structure, e.g., cardiac defects
 (v) Chromosomal factors, e.g.,mongolism, turner's
syndrome, and
 (vi) Immunological factors, e.g.,
agammaglobulinaemia

79.  7. Social agents It is also necessary to consider
social agents of disease.
 These are poverty, smoking, abuse of drugs
and alcohol,unhealthy lifestyles, social
isolation, maternal deprivation, etc.
 Thus the modern concept of disease "agent" is a
very broad one; it includes both living and
non-living agents.

80.  The floating tip of the iceberg represents what
the physician sees in the community, i.e.,
clinical cases.
 The vast submerged portion of the iceberg
represents the hidden mass of disease, i.e.,
latent, inapparent, presymptomatic and
undiagnosed cases and carriers in the
community.
 The "waterline" represents the demarcation
between apparent and inapparent disease.

82.  In some diseases (e.g., hypertension, diabetes,
anaemia, malnutrition, mental illness) the
unknown morbidity (i.e.,the submerged
portion of the iceberg) far exceeds the known
morbidity.

84.  1.RABIES
 2.RUBELLA
 3.TETANUS
 4.MEASSLES.

89.  The main objectives of surveillance are:
 a) to provide information about new and changing
trends in the health status of a population, e.g.,
morbidity, mortality, nutritional status or other
indicators and environmental hazards, health
practices and other factors that may affect health ;
 (b) to provide feed-back which may be expected to
modify the policy and the system itself and lead to
redefinition of objectives, and
 (c) provide timely warning of public health
disasters so that interventions can be mobilized

91.  No routine notification system can identify all
cases of infection or disease. A method for
identifying the missing cases and thereby
supplementing the notified cases is required.
This is known as "sentinel surveillance
The sentinel data is extrapolated to the entire
population to estimate the disease prevalence in
the total population.
The advantages of such a system are that the
reporting biases are minimized, and feed-back of
information to the providers is simplified.