MI05: Infection Disease Terminology

What is the difference between infection and infectious disease?

Infection: colonization by a pathogen on or within the body

Infectious disease: when a microbial infection prevents the body from functioning normally

What is nosocomial infection?

Infection acquired or occurring in a hospital.

What is zoonotic infection?

Infection that normally occurs in animals but can also infect humans.

What is a causative agent?

The microbe/entity responsible for causing the disease.

What is a primary pathogen?

A microbe or virus that causes disease in a healthy individual.

What is an opportunistic pathogen?

It causes disease when the body innate or adaptive immune responses are compromised.

How do infectious diseases progress and resolve?

1. Incubation period: introduction of the pathogen to the host and the onset of signs and symptoms.

2. Illness (disease): time when a host experiences signs and symptoms.

3. Prodromal phase (prodrome): period of early, vague symptoms that precedes the classic illness.

4. Convalescence: stage of recuperation and recovery from the disease.

5. Carrier: individuals that harbor an infectious agent for months or years and can spread the pathogen (even though they look healthy)

What is localized infection?

Microbe is limited to a small area (e.g. Staph aureus boil)

What is systemic infection?

Infection is disseminated (spread) throughout the body, can be characterized by similar signs and symptoms from a systemic immune response.

What is bacteremia?

Bacteria in the blood.

What is sepsis (septic shock)?

A life-threatening systemic inflammatory response due to infection induced bacteremia.

Define viremia.

When there are viral particles in the blood.

Define toxemia.

Toxins circulating in the blood.

What does pathogenic mean?

Something that is able to cause disease.

What is virulence?

The degree of pathogenicity of an organism, capacity of a pathogen to cause disease in a host.

What are virulence factors?

Traits of a microorganism that allow it to cause disease.

Ex: adherence factors, toxins, secretion systems, dissemination factors, etc.