Ch. 15 - Characteristics of Infectious Diseases

What is the definition of a disease?

• Any condition that results in body structure or function being impaired

What can a disease be caused from?

• Microbial infection, genetic, autoimmune

What is the definition of an infection?

• Host colonized by microbe, lead to disease

Is the bacterial colonization of a host always harmful?

• Colonization; not always harmful (part of normal microbiota)

What is chronic? Ex of chronic diseases?

• Long term, slower onset

ex: H. pylori (gastritis)

What is acute? Ex of acute diseases?

• Short lived, rapid onset and resolution

ex: Rhinovirus-common cold

What is a sign? Examples?

• Objective; measured externally by healthcare provider

ex: temperature, heart rate, moisture

What is a symptom? Examples?

• Subjective, internal feeling of subject

ex: dizziness, nausea, pain

What is the definition of syndrome?

• Group of signs and symptoms that are characteristics of a particular disease

What is latent?

• Inactive, not contagious

How is a communicable disease spread?

• Can be spread from person to person

What is a nosocomial disease?

• Acquired in healthcare setting, immunocompromised (opportunistic and antibiotic resistant)

How are zoonotic diseases transmitted?

• Transmitted via animals

How is a noncommunicable disease spread? Ex?

• Not spread person to person; via objects

ex: C. tetani

What is a nonfectious disease? Ex?

• Diseases not caused by pathogens

ex: autoimmune, chronic illness like heart disease

What occurs in the incubation period of disease?

• 1st exposure to microbes

What occurs in the prodromal period of disease?

• Few days; microbes beginning to multiply, 1st symptom

What occurs in the illness period of disease?

• Height of infection, microbes exponentially growing

What occurs in the decline period of disease?

• More microbes dying than being made (less microbes

immune system recognizing and attacking

What occurs in the convalescence period of disease?

• Asymptomatic, can still be spread to others?

At what period of disease can it be spread to others?

• Depends on type of pathogen

What is the purpose of Koch’s postulates?

• A way for us to determine that a particular pathogen is the causative agent for a disease

supports germ theory

In what individuals does an opportunistic pathogen cause disease?

• Don’t cause disease in healthy individuals; those with weakened immune systems

secondary infection; results from antiobiotic

What are examples of opportunistic pathogens?

• Klebsiella pneumonia, Candida Albicans, C diff

In what individuals does a true (primary) pathogen cause disease? Ex?

• Cause disease in everyone, even healthy individuals

ex: V. cholerae causing cholera

What is pathogenecity?

• The virulence or how sick a pathogen can make you

What is a parthenogenesis?

• Process of getting sick to organism multiplying within host

What are the 4 stages of pathogenesis?

1. Initial exposure

2. Adhesion

3. Invasion

4. Infection

In the initial exposure, what must occur between host cell and pathogen?

• Lock and key fit; between host cell and pathogen

In the initial exposure, what is the infectious dose?

• Quantity of pathogenic cells required to cause infection

different for each pathogen

In the adhesion of pathogenesis, what occurs?

• Adhesins (proteins) that binds surface cell receptor to pathogen

specific type of adhesins; for diff. sites

In the invasion of pathogenesis, what occurs?

• Pathogen entering appropriate epithelial cells

What is a virulence factor?

• Enzyme that helps pathogen survive to infect

What is an example of a virulence factor?

• Urease of H. pylori to neutralize stomach acid

What are the 3 types of infection?

1. Local

2. Focal

3. Systemic

What occurs in a local infection? Ex?

• Stays at site of infection

e.g. boil, abrasion

What occurs in a focal infection? Ex?

• Spreads to secondary site

e.g. strep bacteria in oropharynx sending toxins causing endocarditis

What occurs in a systemic infection?

• Infection of toxins spreading throughout system via blood or lymph