Microbial Mechanims And Pathogenicity Lecture 14 Flashcards
Characteristics of Infectious Disease
A disease is any condition in which the normal structure or functions of the body are damaged or impaired
INFECTION CAUSES DISEASE
An infection is the successful colonization of a host by a microorganism
First sign of disease
often found by
observing deviations from normal vital signs
– Temperature, heart rate, blood pressure
Asymptomatic or subclinical disease
Some diseases may not resent any noticeable signs or symptoms
Communicable disease
can spread from person to person
Contagious disease
can easily spread from person to
person
Iatrogenic disease
caused by a medical procedure
Nosocomial disease
acquired in a hospital setting
Zoonotic disease
acquired by transmission from an animal
Noncommunicable disease
acquired from other sources
such as soil and water, but can’t be transmitted to another
Incubation
Pathogenesis has begun, but no signs or symtoms
Prodromal
Signs and symptoms appear
Illness
Acute phase, where signs and symptoms are most obvious
and severe
Decline
Signs and symptoms lessen
Convalescence
Patient generally returns to normal state
Acute diseases
involve pathological changes over a
relatively short period of time (hours to days) with a
rapid onset of signs and symptoms
Chronic diseases
feature changes that happen over
longer periods of time (months, years)
Latent diseases
Feature pathogens that undergo long
periods of dormancy before causing active infection
pathogenicity
an organism’s ability to cause
disease.
Infectivity
how easily a pathogen can cause disease
Virulence
measure of the degree or severity of pathogenicity
Median Infectious Dose (ID50)
Number of pathogen cells or particles (virion) required to
cause disease in 50% of inoculated test subjects
Median Lethal Dose (LD50)
Number of pathogen cells, particles, or amount of toxin
required to kill 50% of test subjects
Primary pathogens
cause disease in a host
regardless of the host’s resident microbiota or immune
system state
Opportunistic pathogens
can only cause disease in a
host who has compromised defenses
