Virulence

Multiple Choice

Why is understanding virulence important in the study of infectious diseases?

• It helps in developing vaccines and treatments

• It only affects non-infectious diseases

• It is not related to disease transmission

• It is only important for plant diseases

Multiple Choice

Which of the following best describes the term 'virulence factors'?

• The ability of a microbe to cause disease

• The degree or extent of disease a pathogen causes

• Mechanisms pathogens use to overcome host defenses

• The balance of normal microbiota

Multiple Select

Which of the following are ways virulence factors can damage host cells?

• Directly damaging host cells

• Provoking dangerous immune responses

• Increasing the host's immune fitness

• Balancing normal microbiota

Fill in the Blanks

Virulence factors are often linked to

, which can help deduce a pathogen’s virulence factors.

Multiple Select

Properties that contribute to virulence

• are determined solely by the microbe.

• are determined solely by the host.

• are fixed and unchanging.

Open Ended

What is the difference between a pathogen’s basic reproduction number (R₀) and effective reproduction number (Rₑ)?

Fill in the Blanks

A pathogen that is still infectious but weakened is described as

.

Multiple Choice

An attenuated pathogen

• has lost virulence factors needed to cause disease in an immune competent host.

• has recently acquired virulence factors allowing it to jump species.

• is part of the normal human microbiome.

• has become antibiotic-resistant

Multiple Choice

Which of the following best describes the term 'Infectious dose-50 (ID50)'?

• The number of cells or virions needed to establish an infection in 50% of exposed hosts

• The amount of toxin required to kill 50% of exposed hosts

• The number of pathogens needed to cause symptoms in all exposed hosts

• The amount of time it takes for a pathogen to infect a host

Multiple Choice

ID50 and LD50 values can change based on which of the following factors?

• Species affected, host's immune fitness, route of exposure

• Type of pathogen, temperature, humidity

• Age of the host, diet, exercise

• Time of day, season, weather

Fill in the Blanks

Toxins that are present in the bloodstream are referred to as

.

Multiple Choice

Which component of the Gram-negative bacterial outer membrane is toxic to humans and other animals?

• Lipid A of lipopolysaccharide (LPS)

• Peptidoglycan

• Teichoic acid

• Flagellin

Multiple Choice

What is the potential consequence of endotoxins being present in sufficient quantities in the body?

• Septic shock

• Allergic reaction

• Fever only

• No effect

Open Ended

How can endotoxins enter the bloodstream? List at least two ways.

Fill in the Blanks

Exotoxins are made by both Gram-positive and

bacteria.

Multiple Choice

Which of the following exotoxins targets the nervous system?

• Neurotoxins

• Enterotoxins

• Hepatotoxins

• Nephrotoxins

Multiple Select

Select all statements that correctly describe Type I exotoxins.

• They are membrane-acting extracellular toxins.

• They bind to target via receptors on the surface.

• They directly kill bacteria.

• They evoke changes in gene expression.

Fill in the Blanks

Diphtheria toxin is produced by

diphtheria.

Multiple Choice

What is one way that understanding R₀ and Rₑ values can help in managing epidemics?

• They help determine the effectiveness of vaccines.

• They indicate the nutritional needs of pathogens.

• They show the genetic makeup of microbes.

• They predict the weather patterns during outbreaks.

Multiple Choice

Which type of bacterial toxin is matched incorrectly with its description?

• Type I exotoxin: Binds to the targeted host cell at a membrane receptor but does not enter the cell

• Type II exotoxin: Disrupts and damages the host cell membrane leading to cell lysis

• Type III exotoxin: Binds to a membrane receptor then enters the cell

• Toxemia: A toxin produced during a viral infection

  Answer:  E