4. EPIDEMIOLOGY
Epidemiology
Epidemiology is the study and analysis of the distribution (who, when,
and where) and determinants of health and disease conditions in
defined populations.
It is the branch of medicine which deals with the incidence, distribution,
and possible control of diseases and other factors relating to health.
5. AIMS
Aims of epidemiology
Epidemiology has three main aims:
To describe disease and other health related event patterns in human
populations.
To identify the causes of diseases and other health related events (also
known as aetiology).
To provide data essential for the management, evaluation and planning
of services for the prevention, control and treatment of disease and
other
6. PURPOSES
Epidemiology has many purposes, including to:
Study the course, or natural history, of disease, determine the frequency
of disease in populations, identify the patterns of disease occurrence,
identify risk factors for and potential causes of disease, and evaluate
the effectiveness of preventative and treatment measures. The ultimate
goal of epidemiology is to apply this knowledge to the control of
disease through prevention and treatment, resulting in the preservation
of public health.
7. COMPONENTS
Epidemiologists use a tool to help understand infectious disease known
as the epidemiologic triangle. The epidemiologic triangle is a model for
explaining the organism causing the disease and the conditions that
allow it to reproduce and spread.
Ecology:
from Greek: οἶκος, "house", or "environment"; -λογία, "study of") is the
branch of biology which studies the interactions among organisms and
their environment. Objects of study include interactions of organisms
with each other and with abiotic components of their environment.
8. ECOLOGICAL CONCEPT OF HEALTH AND
PRACTICE OF COMMUNITY MEDICINE
Basic theme of ecology is that every thing is related to everything else.
According to this approach:
Health may be defined as a state of mind dynamic equilibrium or
adjustment between man and his environment.
Graphically expressed as a balanced scale with pans- Agents and
human host and fulcrum is Environment and health as a state of
equilibrium between disease agent and human host.
9. THE EPIDEMIOLOGICAL TRIANGLE
The epidemiologic triangle is made up of three parts: agent, host and
environment.
Agent
Host
Environment
10. AGENT
An agent could be some form of bacteria, virus, fungus, or parasite.
Physical agent: water, air, soil, temperature, humidity etc
Chemical agent: acid, alkaline, dyes etc
Mechanical agents: automobile, machines used in factories etc
Biological agents: some microorganisms and some macroorganisms
Nutritional agents: excess or lack of food or essential nutrients.
Psychological agents: stress, fear, anxiety etc
11. HOST
Biological traits: It includes genetic characteristics, race, ethinic origin, sex and age
Age is important because:
Young children are more likely to have sub- clinical infections.
Adults are immune to certain diseases because of prior exposure.
Children and adults are exposed to different agents of disease.
Social traits: social traits are acquired as the host goes through life ie marital status, lifestyle, travel etc
Modification of dietary habits, use of alcoholic beverages, change in employment, change in residence.
Human Factors:
Interaction with agents
Individual habits and group customs
Age, sex, race
Defense mechanism
Constitution and heredity
Psychological characteristics
Psychological state
Change in man upset the health and determines the outcome.
12. ENVIRONMENT
Physical factors:
Climate
Setting
Pollution
Diseases prevented by modifying the physical environment e.g filter sting and chlorinating the water supply.
Biological factors:
Environmental factors which help in the existence of agent and its transmission.
Social factors:
Political, social or economic basis of society.
Pre-Pathogenesis Phase:
It is the period preliminary to the onset of disease in man. The diseases agent has not yet entered the man but the factors which favor its
interaction with the human host are already existing in the environment.
Pathogenesis Phase:
The pathogenesis phase begins with the entry of the disease agent in the susceptible human host.
13. DISTRIBUTION OF EPIDEMIOLOGY:
It is concerned with frequency and pattern of health events in a population.
Frequency : refers not only number of health events such as number of cases of
meningitis or diabetes in a population but also the relationship of that number of to
size of population.
▪the resulting rate allow epidemiologist to compared disease occurence across
different population.
Pattern :refers to occurrence of health related events by time, place and person.
▪Time pattern: may be annual , seasonal, weekly, daily , hourly , week day versus
weekend or any other breakdown of time that may influence disease or injury
occurrence .
▪place pattern: include geographic variation , urban /rural differences and
location of work site or schools .
▪Personal characteristics: include demographic factors which may be related
to risk of illness ,injury or disability such as age, sex, marital status and
socioeconomic status as well as behaviors and environmental exposure.
14. APPLICATIONS:
It is one of the sciences of man and therefore makes contribution to
human biology and of human science.
It is one of the sciences of health and therefore makes a contribution to
medical science which in turns provides a rational basis for all medical
practice.
Most specifically, it is the scientific basis for the practice of community
medicine.
15. USES:
Identify factors that cause disease.
Identify factors and conditions that can be used or modified to prevent
the occurrence or spread of disease.
Explain how and why epidemics and diseases occur.
Evaluate the effectiveness of vaccines and different forms of therapy.
To establish a clinical diagnosis of disease.
Evaluate the effectiveness of health programme,
Identify the health needs of community.
Predict the future health needs of a population.
Helps in the study and solution of problems in administration of health
sciences.
16. LEVELS OF PREVENTION
Tertiary Prevention
Disability limitation Rehabilitation
Secondary Prevention
Early diagnosis and prompt treatment
Primary Prevention
Health promotion Specific protection
17. HEALTH PROMOTION:
It involves following things:
Health education.
Good standards of nutrition adjusted to development phases of life
(age/sex).
Attention to personality development (individual and group basis
through counselling and parent education).
Provision of adequate housing, recreation and agreeable conditions at
home and working places.
Marriage counselling and sex education.
Genetics/genetic counselling.
Periodic selective health examination (opportunity for health guidance).
18. SPECIFIC PROTECTION:
Prevention in conventional sense involves measures applicable to one
disease or a group of diseases, before they attack the man.
Measures against micro-organism & non-infective agents and their
sources; e.g. Toxic hazards in industry, nutritional disorders,
carcinogens, allergens, accidents, goitre, dental caries, dental fluorosis.
Measures:
Use of specific immunization.
Attention to personal hygiene.
Use of environmental sanitation.
Protection against occupational hazards.
Protection from accidents.
Avoidance of allergens.
Chemo prophylaxis.
19. EARLY DIAGNOSIS & PROMPT TREATMENT:
Objectives:
To cure and prevent disease process.
To prevent the spread of communicable diseases.
To prevent complications and sequelae.
To shorten period of disability.
Measures:
Case finding techniques.
Screening surveys.
Selective examination.
Examples of case finding techniques:
To rule out malaria :
Blood films should be carefully examined at least 3 times.
20. DISABILITY LIMITATION:
Adequate treatment to arrest the disease process and to
prevent further complications and sequelae.
Provision of facilities to limit disability and to prevent
death.
21. REHABILITATION:
Provision of hospital and community facilities for retaining and
education for maximum use of remaining capacities.
Education of public and industry to utilize the rehabilitated,
Provision of as full employment as possible.
Selective replacement.
Work therapy in hospitals.
Use of sheltered colony.
