Transcript วิทยาการระบาด (EPIDEMIOLOGY)

Introduction
to
Epidemiology
[email protected]
Concept of Epidemiology
Epidemiology is the study of the occurrence, distribution and
determinants (which are dynamic) of health problems and
diseases in human populations or communities. The primary unit
of concern is a group of persons, not any single person.
Therefore, epidemiology deals with population pathology, not
clinical pathology (disease of a single person), nor microscopic
pathology (disease of a cell or tissue). All population pathology
relates back to the community as the source of materials for
investigation and results from epidemiologic study study are
interpreted in terms of the group, not individual.
Epidemiology for...

Epidemic disease
Past
 Communicable disease
 Non-communicable disease
 Non-infectious disease
 Chronic disease
 Occupational disease
 Environmental disease
Present
EPIDEMIOLOGY
EPI
=
DEMOS =
LOGOS =
on, upon
people, population
knowledge, study
doctrine, discourse
science
Evolution of Definition
 The science
or doctrine of epidemics
(New standard Dictionary of English Language)
 The science of infective diseases, their prime
causes, propagation and prevention
(Stallybrass)
 The study of conditions known or reasonably
supposed to influence the prevalence of disease
(Lumsden)
Modern Meaning
 Epidemiology is the science
which concerns itself with the
natural history of disease as it is expressed in groups of
persons related by some common factors of age, sex, race,
location or occupation as distinct from the development of
disease in an individual (American Epidemiological Society)
 Epidemiology is the study of patterns of disease and the
factors that cause disease in man (CDC)
 Epidemiology is the study of the distribution and determinants
of disease frequency in man (MacMahon & Pugh)
Epidemiology
Epidemiology is the study of the
occurrence, distribution,
determinants (which are dynamic) of
health problems and disease in human
populations or communities
Aim an Purposes of Epidemiology
 To describe
and analyze disease occurrences and
distribution according to such variables as age,
race, sex, occupation, temporal frequency of
occurrence, periodic fluctuation, long term trends
(time-trend analysis) and geographic distribution,
in order to make community diagnosis and to
estimate the morbidity and mortality risks.
Aim an Purposes of Epidemiology
 To carefully
analyze the characteristics and
interactions of agents, host and environmental
factors in order to search for causes ; determine all
details of natural history and preventive and
control measures ; and disclose gaps in knowledge.
Aim an Purposes of Epidemiology
 To improve
medical care and provide administrative
guidance for community health services.
 To stimulate the use of systematic approach of
scientific research to study other problems in public
health related fields such as dentistry, welfare,
education, administration and other important spheres.
Scope and Content of Epidemiology

Geographic Pathology
 Clinical Epidemiology
 Identification of Agents of Disease
 Statistical Epidemiology
 Field Survey for Specific Purposes
 Incidence Study (Longitudinal Study)
 Experimental Epidemiology
 Tracing Reservoirs and Sources of Infection
 Administrative Control of Disease
Epidemiological Team
Epidemiology is an applied science, at times it requires
such divergent skill as those of physician, dentist,
veterinarian, public health nurse, sanitarian,
nutritionist, health educator, social worker, statistician,
anthropologist, biochemist, meteorologist and others to
work as a team.
Contributing Factors

Agent
 Host
Environment
A
H
E
Interaction of A, H, E ; Dr. John Gordon
A
H
E
Balance
Interaction of A, H, E ; Dr. John Gordon
H
A
E
Agent changes
Interaction of A, H, E ; Dr. John Gordon
A
H
E
Host changes
Interaction of A, H, E ; Dr. John Gordon
H
A
E
Environment changes facilitates agent spread
Interaction of A, H, E ; Dr. John Gordon
A
H
E
Environment changes alters host susceptibility
Natural History of Disease in man
2 Period
 Prepathogenesis Period
 Pathogenesis Period
- Pre clinical Stage
- Clinical Stage (Mild, Moderate, Severe)
- Disability
Post-interval equillibrium

Recovery or Cure
 Chronic State
 Relapse
 Disability
 Defect
 Death