Epidemiology and public health
Public health, broadly speaking, refers to collective actions to improve population
health
.1 Epidemiology, one of the tools for improving public health, is used in several ways
.Early studies in epidemiology were concerned with the causes
(etiology) of communicable diseases, and such work continues to be essential since it
can lead to the identification of preventive methods. In this sense, epidemiology is a
basic medical science with the goal of improving the health of populations, and
especially the health of the disadvantaged.
Causation of disease
Although some diseases are caused solely by genetic factors, most result from an
interaction between genetic and environmental factors. Diabetes, for example, has
both genetic and environmental components. We define environment broadly to
include any biological, chemical, physical, psychological, economic or cultural
factors that can affect health. Personal behaviors affect this interplay, and
epidemiology is used to study
their influence and the effects of preventive interventions through health promotion .
Natural history of disease
Epidemiology is also concerned with the course and outcome
(natural history) of diseases in individuals and
groups .
. Definition of epidemiology
The word “epidemiology” is derived from the Greek words: epi “upon”, demos
“people” and logos “study”.
This broad definition of epidemiology can be further elaborated as follows:
Term Explanation
Study includes: surveillance, observation, hypothesis testing, analytic
research and experiments.
Distribution refers to analysis of: times, persons, places and classes of people
affected.
Determinants include factors that influence health: biological, chemical,
physical, social,cultural, economic, genetic and behavioural.
Health-related states and events refer to: diseases, causes of death,
behaviours such as use of tobacco,positive health states, reactions to
preventive regimes and provision and
use of health services.Specified populations include those with identifiable
characteristics, such as occupational groups.
Application to prevention and control the aims of public health—to promote,
protect, and restore health.
Causation
Genetic factors
Good health
Environmental factors
(including behaviours)
Ill health
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Health status of populations
Epidemiology is often used to describe the health status of population groups
. Knowledge of the disease burden in populations is essential for health
authorities, who seek to use limited resources to the best possible effect by identifying
priority health programmers for prevention and care. In some specialist areas, such as
environmental and occupational epidemiology, the emphasis is on studies of
populations with particular types of environmental exposure.
Evaluating interventions
Archie Cochrane convinced epidemiologists to evaluate the effectiveness and
efficiency of health services . This means determining things such as the
appropriate length of stay in hospital for specific conditions, the value of treating high
blood pressure, the efficiency of sanitation measures to control diarrhoeal diseases
and the impact of reducing lead additives in petrol.
. Natural history
What is epidemiology? 5
Good health Ill health
Health promotion
Preventive measures
Public health services
Treatment
Medical care
Good health Subclinical
changes
Clinical
disease
Death
Recovery
Proportion with ill health,
changes over time
Good health Time
health
Applying epidemiological principles and methods to problems encountered in
the practice of medicine has led to the development of clinical epidemiology.
Similarly, epidemiology has expanded into other fields such as pharmacy
epidemiology,
molecular epidemiology, and genetic epidemiology .
Molecular and genetic epidemiology
Molecular epidemiology measures exposure to specific substances and early
biological
response, by:
evaluating host characteristics mediating response to external agents, and
using biochemical markers of a specific effect to refine disease categories.
Genetic epidemiology deals with the etiology, distribution, and control of disease in
groups
of relatives, and with inherited causes of disease in populations.
Genetic epidemiological research in family or population studies aims to establish:
a genetic component to the disorder,
the relative size of that genetic effect in relation to other sources of variation in
disease
risk, and
the responsible gene(s).
Public health genetics include:
population screening programs,
organizing and evaluating services for patients with genetic disorders, and
the impact of genetics on medical practice.