MicroBio Chapter 13 Flashcards
The invasion or colonization of the body by microorganisms
Infection
Occurs when an infection results in the change of the state of health and when signs and symptoms appear
Disease
True or False
All infections result in disease
False
Exists if two variables appear to be related by a mathematical relationship
Association
Magnitude of one variable appears o move in the opposite direction of the other associated variable
Negative association (Inverse relationship)
Magnitude of both variable move in the same direction
Positive Association (Direct relationship)
The combination of necessary and sufficient factors that results in disease
Casue
A set of 4 criteria to be met before the relationship between a particular infectious agent and a particular disease is accepted as casual.
Koch’s Postulate (1877)
A set of 9 criteria that each contribute a different amount of strength and likelihood that a relationship between a potential risk factor and a disease is casual
Hill’s Criteria of Causation (1965)
Koch’s Postulate
- The microorganism must be present in all the cases of the disease
- The pathogen can be isolated from the host and grown in pure culture
- The pathogen from the pure culture must cause the disease when inoculated into a healthy, susceptible laboratory animal
- The pathogen must be reisolated from the new host and shown to be the same as the originally introduce pathogen
Hill’ Criteria of Causation
S TRENGTH
C ONSISTENCY
S PECIFITY
T EMPORILTY
B IOLOGICAL GRADIENT
P LAUSIBIITY
C OHERENCE
E EXPERMINET
A NALOGY
A small association does not mean there is not a casual effect. Though larger association means more likely casual effect
Strength
This model of disease has 3 components
Epidemiological triad
3 components of epidemiological triad
- External agent
- Components
- Environmental factors
Can be any microorganism that must be present for a disease to occur
Infectious agents
Intrinsic factors that influence an individual’s exposure. i.e age, race, sex
Host Factors
Are extrinsic factors which affect agent and the host and the opportunity of exposure
Environmental factors
Is the passing of a communicable disease from an infected host
Disease transmission
Dynamics of Disease transmission
Source of reservoir - modes of transmission - Susceptible host
The person, animal or object from which an infectious agent passes or is dessimenated to the host
Source
Any person animal, or substance in which infectious agents lives and multiplies, and depends for survival
Reservoir
Types of Reservoir
- Human
- Animals
- Non-living thing
A person identified as having a particular disease under investigation
Case
An infected person that specific infectious agent in the absence of clinical disease and serves as a potential source of infection
Carrier
The organism causing infectiom
Pathogen
The infected person or animal carrying the pathogen
Host
he method the pathogen uses to leave the body of the host
Exit
How the pathogens is transferred from host to susceptible person
Transmission
The environment in which the transmission of the pathogen take place
Environment
The method the pathogen uses to enter the body of the host
Entry
A potential future host
Susceptible person or animal
Conditions required for infection to spread
- One person must be infected with a microorganism
- The other person must be susceptible to infection
- The microorganism must be able to leave the body of the infected and enter the body of the susceptible
The time between infection agent and onset infectiousness
Latency period
The time between infection and onset of symptoms
Incubation period
The ability of microbe to cause disease
Pathogenicity
The degree of pathogenicity in a microorganism
Virulence
An infection characterized by sudden onset, rapid progression, and often sever symptoms
Acute infection
An infection characterized by delayed onset and slow progression
Chronic infection
An infection that develops in on otherwise healthy person
Primary infection
An infection that develops in an individual who is already infected with a different pathogen
Secondary infection
An infection restricted to a specific location or region within the body of a host
Localized infection
An infection that has spread to several regions or areas of the body
Systemic infection
An infection with few or no obvious symptoms
Subclinical infection
An infection with obvious symptoms
Clinical infection
An infection caused by microorganisms that are commonly found in the host’s environment
Opportunistic infection
The suffix that means presence of infectious agents
emia
A disease that is normally found ina a certain percentage of the population
Endemic disease
A disease present in a greater than usual percentage of the population
Epidemic disease
An epidemic affecting a large geographical area, often on a global scale
Pandemic disease
Presence of infectious agents on the bloodstream
Septicemia
