1. Disease control aims to reduce the incidence, duration, and transmission of diseases as well as their negative physical, psychological, and financial impacts on communities. 2. Disease control involves studying the epidemiological triangle of agent, host, and environmental factors required for a disease to occur. It seeks to control disease by managing the interaction between these factors rather than completely eliminating the disease agent. 3. Disease elimination removes a disease from a large geographical area but not the whole world, while disease eradication removes a disease from all over the world. Smallpox is the only disease that has been eradicated globally so far.

1. Concept Of Disease Control
What Is Disease Control?
Disease Control is the term used to describe operation or activities with the aims;
1. To reduce incidences of diseases.
2. To reduce duration of diseases.
3. To reduce chances of transmission of diseases from one person to another.
4. To reduce negative effects of disease which include both the physical &
psychological complications.
5. To reduce financial burden to the community in case of any disability.
The disease control is dealt while studying Epidemiological Triangle. The agent,
host & environmental factors form three corners of epidemiological triangle.
These three factors are required for a disease to occur & in the absence of any
one of these factors, no disease can occur. These factors are present in our
environment but in isolation form. When the interaction is built among these
factors, man undergoes disease process & moves to Pathogenesis Phase.
Note: - In all cases, disease control doesn’t involve eradicating of the agent of the
disease completely rather than permitting it to persist in a community at a level (if
possible) where it can’t cause health problems.
Epidemiological
Triangle
Agent
EnvironmentHost

2. Disease Elimination (Removal From A Region)
Disease Elimination describes the removal of a particular disease from a large
geographical era but not from the whole world. It is a regional process. It involves
interruption of disease transmission. Examples include removal of measles from
Lahore etc.
Disease Eradication (Removal From The World)
Disease Eradication describes the removal of a particular disease form the whole
of the world not merely from a certain region or a large geographical area. It is an
absolute term which means “tear out by roots”.
The only example of the disease eradication is Small Pox. The world has been
declared free from small pox virus by WHO (World Health Organization).
Natural History Of The Disease
“The way in which a disease evolves in the absence of any intervention is the
Natural History of the Disease”.
The disease results from the complex interaction of three things i-e man (host),
agent (cause of disease) & the environment.
Natural history of the disease involves;
A. Pre-pathogenesis phase (Before man is involved)
B. Pathogenesis phase (After man is involved)
Disease Control
Disease Elimination (Removal from a region)
Disease Eradication (Removal from the world)

3. A. Pre-pathogenesis Phase
Pre-pathogenesis phase is the time period before the onset of disease. As is clear
from background knowledge, three factors are required for a disease to occur
which are;
1. Agent
2. Host
3. Environment
These three factors form the basis of Epidemiological Triangle or Triad.
Note: - If any one of these three factors is missing, disease fails to occur.
During pre-pathogenesis phase, disease is not there i-e man is not involved but
risk of disease is there. For examples, many diseases are there in our society and
we are not the victim of these disease. So we are in the pre-pathogenesis phase
of such diseases.
These three factors are present in our environment but in isolation form. When
the interaction is built among these factors, man undergoes disease process &
moves to Pathogenesis Phase.
B. Pathogenesis Phase
Pathogenesis phase starts when man comes in contact with an agent of disease i-
e with the entry of disease agent into the susceptible human host.
Note: - Once the agent comes into interaction with host & even the symptoms of
the disease don’t appear (incubation period), the man is in pathogenesis phase.
Incubation Period
“Incubation Period is the time period b/w the entry of disease agent into the host
and appearance of signs & symptoms of disease.”
A person in incubation period of pathogenesis phase may be apparently healthy
but some processes (physiological as well as pathological) are going on in the
body which is regarded as sub-clinical. As the incubation period passes, signs and
symptoms of the disease appear.

4. The signs and symptoms are slight in the beginning and progressively become
severe and diagnosis becomes easier. The results of disease may be;
 Complete recovery
 Chronicity
 Disability
 Death
Let’s have a brief discussion about Epidemiological/Ecological/Etiological Triad.
Epidemiological/Ecological/Etiological Triad
The agent, host & environmental factors form three corners of epidemiological
triangle.
What Is An Agent?
“The agent is an organism or force, living or non-living, tangible or non-tangible,
presence or relative deficiency of which can trigger a disease process to occur.”
A single agent may cause different diseases and a disease may have many agents
i-e a single cause may have different effects or a single effect may be cause by
different causes. This results into Multi-factorial Causation and forms Web of
Causation.
Classification Of Agent
Agent may be of following types;
Epidemiological
Triangle
EnvironmentHost
Agent

5.  Biological agent (Insects)
 Nutrient agent (Vitamins, Minerals)
 Physical agent (Hot, Cold, Air pressure)
 Mechanical agent (Friction)
 Chemical agent (Acids, Metals)
 Social agent (Smoking, Poverty)
What Is Host?
Host is mainly the human who is considered as soil and the disease agent is
considered as a seed. Host factors play important role when an interaction take
place b/w agent and host.
Classification Of Host Factors
Host factors are classified as
 Demographic characters (Age, Gender)
 Biological characters (Blood group, Enzymes)
 Social & Economic characters (Socio-economic status, Education)
 Lifestyle factors (Habits, Nutrition)
What Is Environment?
Environment is the place where we live. Certain environmental factors play
important role in disease.

6. The environment is divided into;
 Internal environment (The environment inside our body)
 External environment (the environment outside our body)
External environment is further divided into three types;
1. Physical environment (Air, Water, Housing, Radiations, Noise)
2. Biological environment (Viruses, Bacteria, Parasites, Plants)
3. Social environment (Religion, Caste, Laws, Social systems)
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