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INFEcnous DISEASES 607
Table LO·I. Terminology Associated with Infectious Disease Processes
Antibody
A highly specific prorein that is manufactured in
response ro antigens and defends against subsequent infection
Antigen (immunogen)
An agent that is capable of producing antibodies
when introduced inro the body of a susceptible person
Carrier
A person who harbors an infectious agenr that
can cause a specific disease but who demon·
strates no evidence of the disease
olonization
The process of a group of organisms living
togetherj the host can carry the microorganism without being sympromatic
Communicable
The ability of an infective organism to be transmitted from person to person, either direcdy
or indirecrly
Dissem i na ted
Distribured over a considerable area
Host
The person whom the infectious agent invades
and fr0111 whom it gathers its nourishment
Immunocompromised
An immune system that is incapable of responding to pathogenic organisms and tissue dam·
age
Immunosuppression
The prevention of formation of an immune
response
Nosocomial infection
Infection that is acquired in the hospital setting
Opportunistic
An infectious process that develops in immunosuppressed individuals (Opportunistic infec·
rions normally do nor develop in individuals
with intact immune systems.)
Parhogen
An organism capable of producing a disease
Subclinical infection
A disease or condition that does not produce
clinical symproms, or the rime period before
the appearance of disease·specific symptoms
Physical Examillatioll
Observation
Clinical presentation of infectious diseases is highly variable according to the specific system that is involved. However, common physical findings that occur with infection include sweating and inflammation,
both of which are related to the metabolic response of the body to the
antigen. The classic signs of inflammation (redness and edema) in cer-
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ACUfE CARE HANDBOOK FOR PHYSICAL THERAPISTS
Table 10-2. Components of the Immune System
Lines of Defense
Components
Descri ption
First (ine of
Skin, conjunctivae,
Physical barriers to pathogens.
defense
mucous membranes
Second line of
Inflammamry response
If physical barriers are crossed,
defense
inflammatory response
to (I) contain pathogen and
(2) bring immune cells to
�lntigen.
Third line of
lmmune response
Specific immune response ro
defense
pathogens.
Humoral immunity
B cells produce antibodies.
(B cells)'
Cellular immunity
T cells:
(T cells)'
(1) Augment production of
antibodies.
(2) Dirccdy kill antigens.
(3) Turn off immune system.
-B cells and T cells can also be referred ro as B Iympbocytes or T iyml)hocyces,
respectively.
Sources: Data from NS Rote. Immunity. In SE Heucher, KL McCance (cds), Understanding Pathophysiology (2nd cd). St. Louis: Mosby, 2000;125-150; EN Marich (ed).
Human Anatomy and Physiology (2nd cd). Redwood City, CA: Benjamin Cummins.
1992;690-723; and AC Guyton, JE Hall. Textbook of Medical Physiology (9th ed).
Philadelphia: Saunders, 1996;445-455.
tain areas of the body can help delineate the source, location(s), or
both of infection. Delineating the source of infection is crucial to the
diagnostic process.
Palpation
The presence of warmth and possible pain or renderoess is another
typical sign of inflammation that may be consistent with active infection. Lymphoid organs (lymph nodes and spleen) can also be swollen and tender with infection, as lymphocytes (processed in these organs)
are multiplying in response to rhe antigen. lnAammarion and tenderness .in these or other areas of the body can further help to delineate the infectious process.
INFECllOUS DISEASES 609
Table 10-3. Facrors Affecting the Immune System
Congenital (rare)
Disruption in the development of lymphocytes
Acquired
Pregnancy
Pre-existing infections
Malignancies (Hodgkin's disease, acute or chronic leukemia, nonlymphoid
malignancy or myeloma)
Stress (emotional or surgical-anesthesia)
Malnutrition (insufficiency of calories, protein, iron, and zinc)
Age
Chronic diseases (diabetes, alcoholic cirrhosis, sickle cell anemia)
Immunosuppressive treatment (corticosteroids, chemotherapy, or radiation
therapy)
Indwelling lines and tubes
Source: Data from NS Rote, SE Hcuther, KL McCance. Hypersensitivities, Infection,
and Immunodeficiencies. In SE Heuther, KL McCance (eds), Understanding Pathophysiology (2nd cd). St. Louis: Mosby, 2000;204-208.
Vital Signs
Heart Rate, Blood Pressure, and Respiratory Rate
Measurement of heart rate and blood pressure helps in determining
whether an infectious process is occurring. (Infections result in an
increased metabolic rate, which presents as an increased heart rate
and respiratory rate.) Blood pressure may also be elevated when
metabolism is increased, or blood pressure can be decreased secondary to vasodilation from inflammatory responses in the body.
Temperature
Monitoring the patient's temperature over time (both throughout the
day and daily) provides information regarding the progression (a rise
in temperature) or a regression (a fall in temperature) of the infectious
process. A fall in body temperature from a relatively elevated temperature may also signify a response to a medication.
Auscultation
Heart and lung sounds are examined to determine whether any infectious processes could be occurring from these areas directly or affecting these areas indirectly.