LESSON 2 - INFECTION CONTROL Flashcards
Disease
Is an abnormal state in which part or
all of the body is not properly adjusted or is
unable to carry out usual functions; any deviation
from one’s current condition of health
Infection
Is defined as pathogenic
microorganisms invading the body
Symbiosis
The relation between the
indigenous flora and the host
Commensalism
Is a type of symbiosis in
which one organism benefits from the other
without harming it.
Mutualism
form of symbiosis in w/c both organisms
benefit from the relationship
Parasitism
a connection in which one organism benefits from
another while also harming it.
Pathogen
an organism that invades & causes damage or injury to
the host
Pathogenicity
Refers to an organism’s ability to cause
disease.
Contamination
is defined as the presence of organisms
outside of the body, such as those found in water, food, and other biological
substances.
Pollution
referred to the presence of undesired compounds in water, air, or soil
Pathology and
epidemiology
study of disease
Pathology
study the structural and functional manifestation of disease;
involved in diagnosing diseases in individual
Epidemiology
study the factors that determine the frequency, distribution, and
determinants of diseases in human populations.
Epidemiologists
are scientists who specialize in the study of disease and
injury patterns (incidence and distribution patterns) in populations and
ways to prevent or control diseases and injuries; study virtually all types of
diseases, including heart, hereditary, communicable, and zoonotic diseases and
cancer.
Infectious disease
is a disease that is caused by a pathogen
Communicable
disease
an infectious disease transmissible from one human to
another (i.e., person to person)
Contagious disease
defined as a communicable disease that is easily
transmitted from one person to another.
Zoonotic disease
Infectious diseases that humans acquire from
animal sources are called zoonotic
diseases or zoonoses.
Incidence
incidence of a particular
Period prevalence
number of cases of the disease existing in a
given population during specific time
period
Point prevalence
number of cases existing in a given population at
a particular moment in time
Morbidity
morbidity rate for that disease, which is usually expressed as the number of new
cases of a particular disease that occurred during a specified time period per a
specifically defined population
Mortality rate
ratio of the number of
people who died of a particular disease during
a specified time period per a specified
population
Sporadic disease
one that occurs only occasionally within the population of a
particular geographic area
Endemic disease
diseases that are always present within the population of a
particular geographic are.
Epidemic disease
greater than usual number of cases of a disease in a
particular region
Pandemic Disease
a disease that is occurring in epidemic proportions in
many countries simultaneously – sometimes worldwide.
Kochs Postulates
Is a set of rules for establishing a relationship between a causative
microbe and a disease.
Portal of Entry
The avenue by which a pathogen gains access to the body
Mucous membrane
(Inhaled), Skin (wounds, abrasion) parenteral
Virulence of
organism
The degree of pathogenicity of a microorganism
Capsule
enables organism to evade phagocytosis. Enzymes, Toxins
Number of microbes
microbe, is an organism of microscopic size, which may exist in its single-celled
form or as a colony of cells;
Microbial growth
refers to an increase in number of cells rather than an
increase in cell size; likelihood of disease increases as umber of pathogens
increase
Defensive powers of
host
Immune system
The Bodys Immune
System
provides resistance to disease
Mechanical
organisms directly damage tissues or surface
Chemical
bacteria produces chemicals & toxins
Immunologic
response of the immune system
Toxin
is a specific substance, often a metabolic product of an organism that damages
the host
Incubation period
the time interval between entry of microorganism & the first appearance of s/s
Prodromal period
mild symptoms of a disease w/c are non specific (fever, cough, colds, malaise)
Period of illness
period of maximal invasion. The disease is most acute during this period
Period of decline
pt. does not show s/s but still continues to shed infecting microorganisms
Period of
convalescence
– Period of defervescence- s/s start to subside. - patient Vulnerable to secondary
infection
Human Carriers
most important reservoirs of human infectious
diseases are other humans - people with infectious diseases as well as carriers.
Carrier
is a person who is colonized with a
particular pathogen, but the pathogen is not
currently causing disease in that person
Passive carriers
carry the pathogen without ever having
had the disease.
Incubatory carrier
is a person who is capable of transmitting a pathogen during the incubation
period of a particular infectious disease.
Convalescent
carriers
harbor and can transmit a particular pathogen while
recovering from an infectious disease
Active carriers
have completely recovered from the disease, but
continue to harbor the pathogen indefinitely
Animals
• As previously stated, infectious diseases
that humans acquire from animal sources
are called zoonotic diseases or zoonoses.
• Many pets and other animals are
important reservoirs of zoonoses.
• Zoonoses are acquired by direct contact
with the animal, by inhalation or ingestion of
the pathogen, or by injection of the
pathogen by an arthropod vector.
Rabies virus
is usually transmitted to a human through
the saliva that is injected when
one of these rabid animals bites
the human.
Cat and dogs
Bites often transfer microorganism from
the mouths of these animals
into tissues, where severe
infections may result.
Toxoplasmosis
a protozoan disease caused by
Toxoplasma gondii
• contracted by ingesting oocysts from cat
feces
• ingesting cysts that are present in infected
raw or undercooked meats.
• may cause severe brain damage to, or
death of, the fetus when contracted by a
woman during her first trimester (first
3 months) of pregnancy
Salmonellosis
diarrheal disease, is frequently
Arthropods
are animals, commonly associated with human infections.
Arthropod vector
may first take a blood meal from an
infected person or animal and then transfer the
pathogen to a healthy individual.
- Contact
Transmission
- refers to spread of
microorganism through direct contact, indirect contact or droplet
transmission.
Direct Contact
a.k.a. person to person transmission & involves direct
transmission by physical contact between the source of infection & the
susceptible
host. (kissing, touching).
Ex. Common cold, Respiratory tract infections, chicken pox, syphilis, gonorrhea
Indirect Contact
refers to transmission of causative agent from reservoir to
susceptible host through non living object(fomites) Ex of common fomites:
handkerchiefs, towels, spoons, toys. Ex. of diseases are common colds, sore
eyes, tuberculosis)
Droplet
is a form of contact transmission in w/c the organism is spread in
droplet nuclei that travel only short distances usually <1 meter from reservoir to
the host. These droplets are spread in to air by coughing, laughing, talking,
sneezing. Ex: pneumonia, influenzae
- Vehicle
transmission
refers to transmission of organism through media such as food,
water, air.
Food-borne
pathogens are transmitted through ingestion of food
that are improperly cooked, poorly refrigerated , unsanitary
conditions. ex. Food poisoning, gastroenteritis
Air-borne
- refers to spread of pathogens by droplet nuclei in dust that travels >1 meter
from the reservoir to the host ( ex. measles, tuberculosis)
Water borne
pathogen is spread through contaminated water ( ex , typhoid fever, chole
Amebiasis
(caused by the ameba,Entamoeba histolytica)
Botulism
(caused by the bacterium, Clostridium botulinum)
Cholera
(caused by the bacterium, Vibrio cholerae)
Infectious hepatitis
(caused by hepatitis A virus)
Typhoid fever
(caused by the bacterium, Salmonella typhi)
- Vectors
are animals that carry organism from one host to another Insects
(arthropods) - most important group of
vectors
Mechanical
- refers to passive transport of organism on insect’s feet or other parts.
transmission
Ex: cockroaches & flies
Biological
transmission
active transport of organism. Organism enters the insect vector after
insect vector bites an infected person
