SOCIOECONOMIC STATUS SCALES: KUPPUSWAMY SCLAE B.G PRASAD SCALE Position that an individual or family occupies with reference to prevailing average standards of cultural and material possessions, income and participation in group activity of the community. Societies and communities have various methods of dividing themselves into classes, which form a hierarchy of power and prestige, which defines the functional interrelationships. Societies and communities have various methods of dividing themselves into classes, which form a hierarchy of power and prestige, which defines the functional interrelationships.

1. NATURAL
HISTORY
OF
DISEASE
COMMUNITY
MEDICINE

2.  DEFINITION
 UNDERSTANDING NATURAL HISTORY OF
DISEASE
 ITS IMPORTANCES
 STAGES
 APPLICATION:LEVELS OF
PREVENTION/SCREENING/PROGNOSIS/E
VALUATION
OBJECTIVES

3. DEFINITION
Natural history of disease signifies the way
in which a disease evolves over time from
the earliest stages of its prepathogenesis
phase to its termination as
recovery,disability or death, in the absence
of treatment or prevention.

4.  It refers to the progress of a disease process
in an individual over time, in the absence of
intervention.
 The process begins with exposure to or
accumulation of factors capable of causing
disease.
 Without medical intervention, the process
ends with
 RECOVERY
 DISABITILY
 OR DEATH

5.  Knowledge of the natural history of
disease ranks alongside causal
understanding in importance for disease
prevention ans control.
 Natural history of disease is one of thr
major elements of decriptive
epidemiology.

6.  The natural history of disease is best
established by cohort studies.
 As these studies are costly and laborious,
understanding of the natural history of
disease is largely based on other
epidemiological studies, such as cross
sectional and retrospective studies,
undertaken in difficult population settings.

7.  What the physician sees in the hospital is
just an “episode” in the natural history
of diseases.
 The epidemiologist, by studying the
natural history of disease in the
community setting is in unique position
to fill the gaps in the knowledge about
the natural history of disease.

8. STAGES OF DISEASES

9.  It is a necessary framework to
understand the pathogenetic chain of
events for a particular disease,and for
the application of preventive measures.
 It is customary to describe the natural
history of disease,and as consisting of 2
Phases:
1. PREPATHOGENESIS(the processin environment)
2. PATHOGENESIS(the process in man)

10. PREPATHOGENESIS
PHASE
 This refers to the period preliminary to the onset of
disease in man.
 Disease agent has not entered man, but the factors
which favour its interaction with the human host are
already existing in the environment.
 Situation: “MAN IN THE MIDST OF DISEASE” or “MAN EXPOSED
TO THE RISK OF DISEASE”
 Potentially we are all in the prepathogenesis phase
of many diseases, both communicable and non-
communicable.

11. EPIDEMIOLOGICAL TRIAD

12.  The causative factors of disease may be
classisfied as
 AGENT
 HOST
 ENVIRONMENT
 The major requirement is an
INTERACTION of these three factors to
initiate the disease process in man.
 The epidemiological triad determine
onset of disease and also the distribution
of disease in the community.
EPIDEMIOLOGICAL
TRIAD

13. PATHOGENESIS PHASE
 The pathogenesis phase begins with the entry
of the disease “agent” in the susceptible human
host.
 The disease agent multiplies and induces tissue
period of incubation and later through early
and late pathogenesis.
 The pathogenesis phase may be modified by
intervention measures such as immunization
chemotherapy.

14. EXPOSURE
THEFINALOUTCOMEOF DISEASE

15.  It is useful to remember at this stage that
the host’s reaction with a disease agent is
not predictable.
 That is, the infection with a disease agent is
not predictable.
 In chronic disease(e.g coronary heart
disease, hypertension, cancer), the early
pathogenesis phase is less dramatic.
 This phase in chronic disease is referred to
as presymptomic phase.

16.  The pathological changes are essentially
below the level of the “clinical horizon“.
 The clinical stage begins when
recognisable signs or symptoms appear.
 The disease phase is already well
advanced into the late pathogenesis
phase when signs and symptoms appear.
 In many chronic disease, the agent-host-
environmental interactions are not yet
well understood.

17. BIBLIOGRAPHY
Park, K. (2007) Parks Textbook of
Preventive and Social Medicine.
19th Edition.
IAPSM's Textbook of Community
Medicine