Week 7 - Infection Flashcards
Define infection.
Pathogenic micro-organisms penetrate the host defenses, enter the tissues, and multiply
Define infectious disease.
Pathologic state that occurs due to the disruption of a tissue or organ caused by microbes or their products
Define pathogen.
A microbe whose relationship with its host is parasitic and results in infection and disease
What is the type and severity of infectious disease dependent on?
Pathogenicity of the organism and condition of the host
Define pathogenicity.
The ability of microbial species to produce disease (true and opportunistic pathogens)
Define virulence.
The degree of damage caused by a microbe to its host
Define true pathogen. Give an example.
Causes disease in a healthy person with normal immune defenses
Example: mycobacterium tuberculosis
Define opportunistic pathogen.
Cause disease in immune compromised host and/or cause disease when access to sterile environment
Example: staphylococcus
What are the 6 types of infections?
Primary infection
Reinfection
Superinfection
Secondary infection
Nosocomial infection
Subclinical infection
Define the 6 types of infection.
Primary
Reinfection
Superinfection
Secondary infection
Nosocomial infection
Subclinical infection
Primary infection: initial infection with organism in host
Reinfection: subsequent infection by same organism in a host (after recovery)
Superinfection: infection by same organism in a host before recovery
Secondary infection: when in a host whose resistance is lowered by preexisting infectious disease, a new organism may set up in infection
Nosocomial infection: cross infection occurring in hospital
Subclinical infection: it is one where clinical affects are not apparent
What are 7 details about infectious diseases throughout history?
Infectious agents have probably always caused disease in humans
Smallpox has been described in ancient Egyptian and Chinese writings and may have been responsible for more deaths than all other infectious diseases combined
There is evidence that malaria and poliomyelitis have existed since ancient times
In the 14th Century, the bubonic plague, or Black Death, killed about 20 million people in Europe alone
In the 20th Century, the 1918 influenza may have killed up to 50 million people worldwide
Close to 20 million people have died of AIDS to date
Potato blight (cause of the Irish Potato Famine)
What are the 3 classifications of infectious disease?
Duration, location, and timing
What kinds of diseases are classified by duration?
Acute: develops and runs its course quickly
Example: influenza
Chronic: develops more slowly and is usually less severe, but may persist for a long, indefinite period of time
Example: tuberculosis
Latent: characterized by periods of no symptoms between outbreaks of illness
Example: herpes
What kinds of diseases are classified by location?
Local: confined to a specific area of the body
Systemic: a generalized illness that infects most of the body with pathogens distributed widely in tissues
What kinds of diseases are classified by timing?
Primary: initial infection in a previously healthy person
Secondary: infection that occurs in a person weakened by a primary infection
What are the 6 phases of infectious disease?
- Exposure
- Incubation period: time between infection and appearance of signs and symptoms
- Prodromal period: mild, nonspecific symptoms that signal the onset of some diseases
- Acute stage: person experiences typical signs and symptoms of disease
- Recovery stage: symptoms have disappeared, tissues have healed, and body is slowly recovering strength
- Convalescence: clinical symptoms have actually subsided
What 6 elements are needed for the chain of infection?
- Infectious agent
- Reservoir
- Portal of exit
- Mode of transmission
- Portal of entry
- Susceptible host
