2. An abnormal condition affecting the body of an
organism
Often construed to be a medical condition associated
with specific signs and symptoms
May be caused by factors originally from an external
source such as infectious diseases or internal
dysfunctions such as autoimmune diseases
Any condition that causes pain, dysfunction, distress,
social problems, or death to the person affected
3. Physical injuries or disabilities are not
classified as disease
There can be several causes for disease,
including infection by a pathogen, genetics
(as in many cancers or deficiencies),
noninfectious environmental causes, or
inappropriate immune responses
4. The successful colonization of a host by a
microorganism
Can lead to disease, which causes signs and
symptoms resulting in a deviation from the
normal structure or functioning of the host
Microorganisms that can cause disease are
known as pathogens
5. Signs are objective and measurable, and can be
directly observed by a clinician.
Vital signs, which are used to measure the body’s
basic functions, include:
Body temperature (normally 37 °C [98.6 °F])
Heart rate (normally 60–100 beats per minute)
Breathing rate (normally 12–18 breaths per minute)
Blood pressure (normally between 90/60 and 120/80
mm Hg)
6. Symptoms of disease are subjective.
They are felt or experienced by the patient, but cannot be
clinically confirmed or objectively measured.
Examples of symptoms include nausea, loss of appetite, and
pain. Such symptoms are important to consider when
diagnosing disease, but they are subject to memory bias and
are difficult to measure precisely.
Some clinicians attempt to quantify symptoms by asking
patients to assign a numerical value to their symptoms.
7. A specific group of signs and symptoms
characteristic of a particular disease
Many syndromes are named using a
nomenclature based on signs and
symptoms or the location of the disease
8.
9. Morbidity - the number of cases of a disease
Mortality - the number of deaths due to a disease
Communicable - capable of being spread from person
to person through either direct or indirect mechanisms
Non-communicable infectious disease - not spread
from one person to another (e.g. tetanus)
Non-infectious diseases - not caused by pathogens
(e.g. Down syndrome)
10. Iatrogenic diseases - diseases that
are contracted as the result of a
medical procedure are known as
Zoonotic diseases - not transmitted
between humans directly but can be
transmitted from animals to humans
13. The onset of contagious disease
wherein the virus multiplies until it
affects the body’s defenses
The period when infection and the first
signs and symptoms associated with a
disease appear
14. During this stage, a sick person may actually spread
the disease-causing microorganisms without knowing
because this is symptom-less stage where microbes
can multiply inside the body and also spread to other
people
The length of this period is dependent on the kind
of microorganism that invades the person and his/her
immune system
For example, the incubation period of chickenpox is
14-16 days and COVID-19 for 5-14 days
15.
16. During this stage, although the person does not
feel weak, sick, or may not appear sick, the
virus has become stronger than the body’s
defenses
The illness may be spread to other people
This is a short stage of disease development
where a person begins to feel that they are
getting sick
17. The signs and symptoms during this
stage typically result from activation
of the immune system, such as
fever, pain, soreness, swelling, or
inflammation.
18.
19. The illness has developed
In case of flu, fever, aches, and pains,
and other symptoms are present
This is the stage where a person feels
the typical signs and symptoms
associated with the disease
20. This is also the stage where the person
can most easily transmit a
communicable disease to another
person
The peak of illness intensity is known
as acme point
21.
22. This is the stage of disease development
where the immune system begins to bring
microbial replication under control which
leads to the lessening of the signs and
symptoms associated with the disease
Damaged tissues begin to repair, and
pathogen numbers decrease
23.
24. This is the final stage of the disease
process where the microbial replication is
fully stopped and the person returns to the
pre-illness stage
Although depending on the disease, the
person may not proceed to this stage and
may die from their disease or be disabled
25. The progression of an infectious disease can be divided into five periods, which are related
to the number of pathogen particles (red) and the severity of signs and symptoms (blue).
