Disease Transmission and Zoonosis Quiz
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Questions and Answers

Which of the following diseases is NOT a zoonotic disease?

  • Anthrax
  • Rabies
  • Cholera (correct)
  • Brucellosis
  • What is a 'fomite' in the context of disease transmission?

  • An airborne particle carrying infectious agents
  • A droplet expelled during coughing or sneezing
  • A contaminated object that transmits disease indirectly (correct)
  • A type of bacteria that causes food poisoning
  • Which disease outbreak did Dr. John Snow famously link to a contaminated water pump?

  • Anthrax
  • Salmonella
  • Legionnaires' disease
  • Cholera (correct)
  • What is the primary mode of transmission for diseases like Influenza, Pneumonia, and Meningococcal infections?

    <p>Droplets spread through the air (A)</p> Signup and view all the answers

    How might someone contract anthrax from an animal source?

    <p>Handling contaminated animal hide products (A)</p> Signup and view all the answers

    Which transmission method BEST describes the spread of HIV?

    <p>Direct contact (B)</p> Signup and view all the answers

    Where does Legionnaires' disease often originate?

    <p>Water supplies in cooling towers (B)</p> Signup and view all the answers

    Trichinellosis is transmitted to humans from infected:

    <p>Swine (D)</p> Signup and view all the answers

    Which of the following diseases are transmitted by invertebrate vectors like ticks, mosquitoes, and fleas?

    <p>Lyme's disease and Malaria (D)</p> Signup and view all the answers

    What are some of the environmental challenges a pathogen must overcome to successfully transmit through different routes?

    <p>Variations in pH, temperature, and oxygen levels (C)</p> Signup and view all the answers

    What is the primary function of adhesion in pathogens?

    <p>Successful colonization within the host (C)</p> Signup and view all the answers

    What is the definition of pathogenicity?

    <p>The capacity of an organism to initiate an infectious disease. (C)</p> Signup and view all the answers

    Which of the following are examples of adhesion factors used by pathogens?

    <p>Attachment proteins and specialized surface structures (A)</p> Signup and view all the answers

    Which of the following best describes virulence factors?

    <p>Proteins or molecules produced by an organism essential for its pathogenicity. (C)</p> Signup and view all the answers

    What is the primary role of fimbriae/pili in bacterial adhesion?

    <p>Enabling bacteria to stick to host cells (C)</p> Signup and view all the answers

    What is the role of membrane-associated virulence factors?

    <p>To aid in adhesion to host tissues/cells and evasion of host immunity. (A)</p> Signup and view all the answers

    Aside from motility, what other function can flagella sometimes serve?

    <p>Adhesion to host cells (C)</p> Signup and view all the answers

    What are Type IV Pili primarily used for?

    <p>Transferring DNA, like antibiotic resistance plasmids, between bacteria (B)</p> Signup and view all the answers

    What is the primary function of secretory virulence factors?

    <p>To invade tissues and/or evade the host's innate and adaptive immune response. (C)</p> Signup and view all the answers

    What is a reservoir in the context of disease transmission?

    <p>The natural site of a pathogen. (C)</p> Signup and view all the answers

    What role do exopolysaccharides (EPS) play in bacterial adhesion?

    <p>They mediate attachment to surfaces (A)</p> Signup and view all the answers

    What distinguishes a human reservoir from an animal reservoir?

    <p>Humans are incidental hosts in animal reservoirs. (D)</p> Signup and view all the answers

    Which of the following steps in bacterial infection involves breaking through host barriers?

    <p>Invasion (A)</p> Signup and view all the answers

    What is infectivity in the context of bacterial pathogenesis?

    <p>The ability to breach host defenses in the first place. (D)</p> Signup and view all the answers

    What is the function of the "Toxin Complex" in bacterial pathogens?

    <p>To directly inject toxic proteins into host cells (A)</p> Signup and view all the answers

    What is TSST-1?

    <p>A toxin produced by some Staphylococcus aureus strains (A)</p> Signup and view all the answers

    Which of the following are examples of molecules produced by multi-enzyme 'factories' in bacteria?

    <p>Siderophores (B)</p> Signup and view all the answers

    What is the role of non-ribosomal peptide synthases (NRPS)?

    <p>Synthesizing non-protein toxins (B)</p> Signup and view all the answers

    What is the significance of specialized toxin delivery systems in bacterial pathogens?

    <p>They contribute to pathogenicity and virulence (A)</p> Signup and view all the answers

    Which organisms are known to utilize the 'Toxin Complex' delivery system?

    <p>Insects, mammals, and fish (B)</p> Signup and view all the answers

    How do some bacteria deliver virulence factors directly into host cells?

    <p>Via direct injection upon contact (C)</p> Signup and view all the answers

    What is the primary function of exopolysaccharides (EPSs) produced by bacteria?

    <p>To promote adhesion to surfaces and protect against harmful substances. (A)</p> Signup and view all the answers

    How do bacterial capsules contribute to pathogenicity?

    <p>By shielding bacteria from immune detection and antimicrobial agents. (C)</p> Signup and view all the answers

    What is a key characteristic of biofilms that contributes to bacterial survival?

    <p>They form a complex structure that allows for nutrient flow and waste removal. (B)</p> Signup and view all the answers

    How does the scavenging of serine by pathogens contribute to their survival?

    <p>Serine disrupts host immune cell function by limiting energy availability. (C)</p> Signup and view all the answers

    What is the primary effect of LPS (endotoxin) on the host?

    <p>Induction of fever and inflammation. (C)</p> Signup and view all the answers

    What is the mechanism of action of superantigens?

    <p>They directly activate T-cells, leading to an excessive release of cytokines. (A)</p> Signup and view all the answers

    Which of the following is NOT a typical component of a biofilm?

    <p>Lipids (B)</p> Signup and view all the answers

    What is dental plaque an example of?

    <p>A mixed-species biofilm (D)</p> Signup and view all the answers

    Flashcards

    Pathogen

    An organism that causes disease to its host.

    Pathogenicity

    The capacity to initiate an infectious disease.

    Virulence

    The capacity to cause disease and its severity.

    Transmissibility

    The ability to transmit between hosts.

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    Virulence factors

    Proteins or molecules essential for pathogenicity.

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    Steps to infection

    Survival, transmission, adherence, invasion, tissue damage.

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    Human reservoirs

    Humans that carry pathogens, can transmit without symptoms.

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    Animal reservoirs

    Sources of pathogens that primarily infect animals; humans are incidental hosts.

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    Invertebrate vector

    Organisms like ticks, mosquitoes, and fleas that transmit pathogens.

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    Pathogen adaptability

    The ability of pathogens to survive in various environmental conditions.

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    Adhesion

    The process by which pathogens attach to host cells or tissues.

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    Attachment proteins

    Proteins that facilitate the attachment of pathogens to host cells.

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    Fimbriae

    Short protein fibers that enable bacteria to stick to surfaces.

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    Flagella

    Long filaments used primarily for bacterial motility and attachment.

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    Type IV pili

    Specialized pili that aid in DNA transfer among bacteria.

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    Exopolysaccharides (EPS)

    Generic surface structures that aid attachment and biofilm formation.

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    Zoonosis

    Transmission of diseases from animals to humans.

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    Environmental Reservoirs

    Natural environments that can harbor infectious agents, e.g., plants, soil, water.

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    Vibrio Cholera

    Bacteria found in contaminated water causing Cholera outbreaks.

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    Direct Contact Transmission

    Transfer of microorganisms through direct physical interaction between people.

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    Indirect Contact Transmission

    Microorganisms spread via contact with contaminated objects (fomites).

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    Droplet Transmission

    Microorganisms spread through droplets when someone coughs, sneezes, or talks.

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    Zoonotic Diseases from Animal Bites

    Diseases transmitted through bites from infected animals, such as Rabies.

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    Contaminated Animal Products

    Diseases from consuming infected animal products like meat or dairy.

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    Capsule

    A structure made of EPSs that protects bacteria from immune responses.

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    Biofilm

    A complex community of bacteria that adheres to surfaces and can enhance survival.

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    Toxins

    Substances produced by pathogens that can cause harm to host cells.

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    Endotoxin (LPS)

    A component of the outer membrane of bacteria that triggers inflammation.

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    Superantigens

    Proteins that cause uncontrollable T-cell activation leading to excess cytokines.

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    Cytokine storm

    A severe immune reaction involving excessive inflammatory cytokine release.

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    Active combat mechanisms

    Strategies used by pathogens to fight against host defenses.

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    Toxic Shock Syndrome Toxin-1

    A toxin produced by Staphylococcus aureus that causes Toxic Shock Syndrome (TSS).

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    Multi-protein injection machine

    A complex used by pathogens to inject toxic proteins into host cells.

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    Toxin Complex

    A system that delivers multiple toxic proteins directly to host cells.

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    Polyketide synthesis

    A process used by some bacterial toxins to create antibiotic and immune-inhibiting substances.

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    Gram-positive bacteria

    Bacteria with a thick cell wall, important in pathology and toxin secretions.

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    Gram-negative bacteria

    Bacteria with a thin cell wall and outer membrane, often more virulent.

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    Specialized toxin delivery systems

    Mechanisms that bacteria use to deliver toxins directly into host cells.

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    Study Notes

    Mechanisms of Bacterial Virulence

    • Bacterial pathogens cause disease
    • Pathogenicity is the ability to initiate disease
    • Virulence is the severity of disease. Measures virulence using LD50
    • Transmissibility is the ability to spread from one host to another
    • Survival is the ability to withstand host immunity and reproduce
    • Infectivity is the ability to breach host defenses
    • Virulence factors are essential proteins or molecules for pathogenicity

    Virulence Factors

    • Cytosolic factors involve metabolic, physiological, and morphological changes
    • Membrane-associated factors aid adhesion to host tissues/cells and evade host immunity
    • Secretory factors invade tissues and evade innate and adaptive immunity

    Steps to Infection

    • Transmission: Exposure to pathogens
    • Adherence: Binding to skin/mucosa
    • Invasion: Breaking through barriers
    • Survival: Growth at original and distal sites, production of virulence factors
    • Tissue Damage: Toxicity and disease

    Transmission: Reservoirs

    • Human: Person-to-person transmission, asymptomatic carriage (e.g., COVID, HIV)
    • Animal: Animal-to-animal, with humans as incidental hosts (e.g., Brucellosis, Anthrax, Plague)
    • Environmental: Plants, soil, and water (e.g., Cholera, Legionnaires disease)

    Transmission: Mechanisms

    • Direct Contact: Physical transfer between infected individuals (e.g., skin-to-skin, sexual)
    • Indirect Contact: Contact with a contaminated object (fomites) (e.g., Cholera, Salmonellosis)
    • Droplets: Transmission via airborne droplets produced by coughing, sneezing (e.g., Influenza, Pneumonia)
    • Zoonoses: Transmission from animals to humans (e.g., Animal bites, food products, animal hide products, invertebrate vector-borne)

    Portals of Entry and Exit

    • Portals of entry include mucous membranes, skin damage, placenta/birth transmission, specialised entry, and vector transmission.
    • Portals of exit include respiratory tract, gastrointestinal tract, genitourinary tract, skin, and blood.

    Factors Affecting Pathogen Transmission

    • Environmental conditions: temperature, pH, oxygen levels, salt levels, host immune responses, nutrient availability

    How Pathogens Achieve Infection

    • Cell Surface Components: Adhesion, entry and structural defence against immunity
    • Active Combat: Invasive enzymes, nutrient acquisition, toxins
    • General Strategies: Dealing with phagocytosis, communication, subverting apoptosis

    Adhesion

    • The process of organisms attaching to tissues or cells
    • Necessary for successful colonization
    • Adhesion factors:
      • Attachment proteins (pili, fimbriae, flagella)
      • Specialized surface structures (EPS, CPS)

    Adhesion Structures

    • Initial attachment often mediated by protein appendages:
      • Fimbriae/pili: Short fibers for sticking to host cells
      • Flagella: For movement

    Surface Structure (EPS)

    • Exopolysaccharides (EPS): Consist of monosaccharide polymers secreted by bacteria into their environments
    • Function: Hydrophobic, displace water, promoting closer contact, protective shield (capsule), prevent phagocytosis

    Biofilms

    • Formed by bacteria after initial attachment to enhance survival
    • Locations: Inside host tissues, on abiotic surfaces (dental plaque, intestines)
    • Structure: Contain biological polymers (exocellular polysaccharides, DNA, proteins)
    • Function: Barrier against harmful factors, antibiotics and immune factors cannot penetrate.

    Active Combat: Invasive Enzymes

    • Coagulase: Coagulates fibrinogen, facilitates bacterial entry
    • Kinases: Digest fibrin clots, breakdown host clots
    • Hyaluronidase: Digests intercellular hyaluronic acid, spreading bacteria through tissues
    • Collagenase: Hydrolyses collagen tissue, allowing bacteria greater freedom
    • IgA protease: Destroy IgA antibodies, combating the host's immune system.

    Active Combat: Toxins

    • Toxin: Substance contributing to pathogenicity
    • Toxigenicity: Ability to produce toxin
    • Toxemia: Presence of toxin in the host's blood
    • Toxoid: Inactivated toxin used in a vaccine
    • Antitoxin: Antibodies against a specific toxin
      • Examples are botulinum, shiga toxins, staphylococcal.
    • Toxins vary in effect and potency and can be quite specific

    Active Combat: LPS

    • Gram-negative bacteria outer membrane component
    • Triggers TLR4, causing inflammatory responses and fever
    • Little innate toxicity itself

    Active Combat: Exotoxins

    • Specifically synthesized and released in response to host signals
    • Types:
      • Single polypeptide toxins
      • Multiple polypeptide toxin complexes
      • Small "drug-like" molecules
      • Toxins directly "injected" by specialist secretion systems

    Active Combat: Single Chain Toxins

    • Example: S. aureus α-toxin creates pores in host cell membranes
    • Many toxins disrupt phospholipid bilayers

    Active Combat: Superantigens

    • Directly target immune system
    • Trigger non-specific T-cell activation, cytokine storm
    • Bridge between class II MHC and TCR

    Active Combat: Multiple Subunit Protein Toxins

    • Multi-protein injection machines delivering toxic payloads across host cell membranes

    Active Combat: Non-protein Small Drug-like Toxins

    • Other toxins are evolved specifically to damage or manipulate the host
    • Some examples include toxins, immune inhibitors, antibiotics, siderophores

    Multi-enzyme "Factories"

    • Secondary metabolite genes like NRPS act as factories to produce molecules
    • Molecules include toxins, immune inhibitors, antibiotics, siderophores

    Active Combat: Specialized Toxin Delivery Systems

    • Secretion systems for toxin release into host cells
    • Types:
      • Type I, Type II, Type III, Type IV, Type V, Type VI, Type VII
    • Occur in both Gram-positive and Gram-negative bacteria

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    Description

    Test your knowledge on disease transmission methods and zoonotic diseases with this quiz. It covers various topics including historical outbreaks, modes of transmission, and infection sources. Challenge yourself to identify key concepts in the field of epidemiology.

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