Cph 2b And 3 Flashcards
are extrinsic factors
which affect the agent and the
opportunity for exposure.
Environmental factors
intrinsic factors that
influence an individual’s exposure,
susceptibility, or response to a causative
agent.
HOST FACTORS
agent might be
microorganism—virus, bacterium,
parasite, or other microbes. e.g. polio,
measles, malaria, tuberculosis Generally,
these agents must be present for disease
to occur
Infectious Agents
excesses or deficiencies
(Cholesterol, vitamins, proteins)
Nutritive
(carbon monoxide,
drugs, medications)
Chemical angent
(Ionizing radiation,…
Physical angent
is an event, condition, or
characteristic without which the disease
would not have occurred.
Cause
“…a complete causal
mechanism” that “inevitably produces
disease.” is not a single factor, but
a minimum set of factors and circumstances
that, if present in a given individual, will
produce the disease.
A sufficient cause
Each component in a sufficient cause is called
Component cause
A component cause that must be present in every
sufficient cause of a given outcome is referred to as
A necessary cause
The components of a sufficient cause do not need
to act simultaneously; they can act at different
times. True or false?
True
There is no single cause
Causes of disease are interacting
T or F?
True
Pre-exposure period in the natural
history of disease, in which the
individual in the population is
vulnerable or at risk to acquire the
infection.
Stage of susceptibility
Sometimes called a pre-infection
Pathological changes occur but no
obvious recognizable clinical
findings.
Stage of subclinical disease
Has recognizable manifestations
Manifestations of the disease are the
clinical evidence of effects, the signs
and symptoms of disease
Stage of clinical disease
those diseases
caused by biological agents or their
products and are transmissible from one
individual to another
Communicable disease
those
diseases that cannot be transmitted from
one person to another
Non-communicable disease
peak severity of symptoms
occurs and subsides within three months
(usually sooner) and the recovery of those who
survive is usually complete.
Acute disease
symptoms continue longer
than three months, and in some cases, for the
remainder of one’s life; recovery is slow and
sometimes incomplete.
Chronic diseases
the ability of a biological
agent to lodge and grow in a host
Infectivity
an infectious disease
agent’s ability to produce disease
Pathogenicity
a pathogen’s ability to
cause damage to a host; the degree of
damage caused by a microbe to a host
Virulence
factors produced by
microorganisms that enable them to
invade a host; evade host defenses and
evoke disease
Virulence factors
(Epidemiologic triangle)
is the element that must be present
for disease to occur.
Agent
is any susceptible organism—a
single-celled organism, a plant, an animal,
or a human—invaded by an infectious
agent.
Host
Includes all other factors—
physical, biological, or social—that inhibit
or promote disease transmission.
Environment
Unicellular microorganisms which have
cell walls but lack organelles and an
organized nucleus, including some which
can cause disease
▪ Classified as either Gram Positive that
releases Exotoxin or Gram Negative that
releases Endotoxin.
Bacteria
Biological agent that reproduces inside
the cells of living hosts.
▪ Infective agent that typically consists of a
nucleic acid molecule in a protein coat, is
too small to be seen by light microscopy,
and is able to multiply only within the living
cells of a host.
Virus
One-celled or multicellular organism that
are relatedly distant to plants but closer to
the animal kingdom.
Fungi
are organisms that live on or in a
host organism and gets its food from or at
the expense of its host.
Parasite
Three main classes of parasites that can
cause disease in humans:
a. Protozoa: single-celled eukaryotes
b. Helminths: are worm-like parasites.
c. Ectoparasites: are organisms that live
on the skin of a host
Conceptual model that reflects the
transmission of communicable disease
from its source to the susceptible host.
Chain of infection
Habitat in which
the agent normally live, grow and
multiply.
Reservoir
Resistance
▪ Ability to ward off damage or
disease through our defenses
Immunity
Any low-molecular-weight regulatory protein
or glycoprotein secreted by immune cells or
other cells of the body which mediate and
regulate immunity, inflammation and
hematopoiesis
▪ Produced in response to an immune stimulus
▪ Bind to specific receptors on the membrane
target cells, triggering signal-transduction
pathways that ultimately alter gene
expressions in the target cells
Cytokines
Convalescent immunity that occurs when a person
recovers from infection
▪ Lifetime (measles, mumps) or temporary (scarlet fever
Natural active
Provided by mothers through transplacental transfer and
through breastfeeding
▪ Maternal antibodies to specific diseases are passed to
the infant and protect the child during vulnerable first
months of life
Natural Passive
Introduction of a killed or weakened form of
the disease organism through vaccination
(vaccine-induced immunity)
Artificial Active
Is achieved by infusion of serum or plasma
containing high concentrations of antibody
Artificial passive
containment of a disease and can
include both prevention and intervention
measures; the limiting of transmission of a
communicable disease in a population
Control
the uprooting or total elimination
of a disease from the human population. It is an
elusive goal, one that is only rarely achieved in
public health.
Eradication
the separation, for the period of
communicability, of infected persons or
animals from others so as to prevent the
direct or indirect transmission of the
communicable agent to a susceptible
person.
Isolation
limitation of the freedom of
movement of well persons or animals that
have been exposed to a communicable
disease until the incubation period has
passed.
Quarantine
