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What is the primary means of transmission of Herpes simplex virus?
What is the primary means of transmission of Herpes simplex virus?
Which type of transmission involves the inhalation of small pathogens and particles suspended in air?
Which type of transmission involves the inhalation of small pathogens and particles suspended in air?
What is the primary means of transmission of Influenza?
What is the primary means of transmission of Influenza?
Which of the following is an example of Vehicle transmission?
Which of the following is an example of Vehicle transmission?
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What is the primary means of transmission of Diphtheria?
What is the primary means of transmission of Diphtheria?
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Which of the following is an example of Contact transmission?
Which of the following is an example of Contact transmission?
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What is the primary means of transmission of Respiratory syncytial virus?
What is the primary means of transmission of Respiratory syncytial virus?
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Which of the following is NOT an example of Vehicle transmission?
Which of the following is NOT an example of Vehicle transmission?
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What is the primary mechanism of action for nucleic acid synthesis inhibitors against bacteria?
What is the primary mechanism of action for nucleic acid synthesis inhibitors against bacteria?
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Which of the following is a principle of action for antiviral agents that target nucleic acid synthesis?
Which of the following is a principle of action for antiviral agents that target nucleic acid synthesis?
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What is the definition of antimicrobial resistance?
What is the definition of antimicrobial resistance?
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What is the primary target of protein synthesis inhibitors that exploit the differences between eukaryotic and prokaryotic ribosomal proteins, RNAs, and associated enzymes?
What is the primary target of protein synthesis inhibitors that exploit the differences between eukaryotic and prokaryotic ribosomal proteins, RNAs, and associated enzymes?
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Which of the following is a major step targeted by common antiviral agents?
Which of the following is a major step targeted by common antiviral agents?
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What is the mechanism of action of antiviral agents that target assembly and budding of viral particles?
What is the mechanism of action of antiviral agents that target assembly and budding of viral particles?
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What is a common characteristic of emerging diseases?
What is a common characteristic of emerging diseases?
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Which of the following is an example of ecological changes that alter the composition and size of reservoirs?
Which of the following is an example of ecological changes that alter the composition and size of reservoirs?
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What is the primary mode of transmission for Hepatitis A?
What is the primary mode of transmission for Hepatitis A?
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Which of the following is an example of a nosocomial infection?
Which of the following is an example of a nosocomial infection?
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What is the primary difference between direct contact transmission and indirect transmission?
What is the primary difference between direct contact transmission and indirect transmission?
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Which of the following emerging diseases is an example of a re-emerging infection?
Which of the following emerging diseases is an example of a re-emerging infection?
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What is the primary mode of transmission for Smallpox?
What is the primary mode of transmission for Smallpox?
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Which of the following is an example of an emerging disease caused by a newly identified strain of a known infection?
Which of the following is an example of an emerging disease caused by a newly identified strain of a known infection?
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What is the main reason why there are fewer antiviral drugs available compared to antibacterial drugs?
What is the main reason why there are fewer antiviral drugs available compared to antibacterial drugs?
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What is the primary mechanism of bacterial resistance through modification of the drug's target site?
What is the primary mechanism of bacterial resistance through modification of the drug's target site?
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Which type of viral genome is more prone to developing resistance due to the error-prone polymerase enzyme?
Which type of viral genome is more prone to developing resistance due to the error-prone polymerase enzyme?
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What is the primary difference between bactericidal and bacteriostatic antibacterial agents?
What is the primary difference between bactericidal and bacteriostatic antibacterial agents?
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What is the primary purpose of combination therapy in the treatment of chronic infections?
What is the primary purpose of combination therapy in the treatment of chronic infections?
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What is the primary target of antibacterial agents that inhibit cell wall synthesis?
What is the primary target of antibacterial agents that inhibit cell wall synthesis?
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What is the characteristic of memory cells in immunological memory?
What is the characteristic of memory cells in immunological memory?
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What is the mechanism of action of antibacterial agents that target the plasma membrane function?
What is the mechanism of action of antibacterial agents that target the plasma membrane function?
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Which of the following statements is true about antibacterial agents?
Which of the following statements is true about antibacterial agents?
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What type of adaptive immunity involves the administration of antibodies to a non-immune individual?
What type of adaptive immunity involves the administration of antibodies to a non-immune individual?
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What is the primary function of effector cells in immunological memory?
What is the primary function of effector cells in immunological memory?
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What determines whether an antibacterial agent is broad-spectrum or narrow-spectrum?
What determines whether an antibacterial agent is broad-spectrum or narrow-spectrum?
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What is the outcome of clonal expansion in immunological memory?
What is the outcome of clonal expansion in immunological memory?
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Which of the following is a specific target of some antibacterial agents that affect the plasma membrane function?
Which of the following is a specific target of some antibacterial agents that affect the plasma membrane function?
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What is the primary reason why antibacterial agents are effective against bacteria but not against human cells?
What is the primary reason why antibacterial agents are effective against bacteria but not against human cells?
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What is the primary difference between active and passive immunity?
What is the primary difference between active and passive immunity?
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Study Notes
Emerging Diseases
- An emerging disease is a newly identified infection, or a previously recognized infection that has expanded into a new ecological niche, often accompanied by a significant change in pathogenicity.
- Many emerging diseases are zoonotic, meaning an animal reservoir incubates the organism, with only occasional transmission into human populations.
- Causes of emerging diseases include:
- Newly identified species (e.g. HIV and AIDS)
- Newly identified strains that have evolved from a known infection (e.g. influenza)
- Ecological changes that alter the composition and size of reservoirs (e.g. Lyme disease)
- Spread to a population in a new area of the globe (e.g. West Nile fever)
- Re-emerging infections like drug-resistant tuberculosis
- Nosocomial (hospital-acquired) infections, such as Methicillin-resistant S. aureus
Disease Transmission
- Main modes of transmission:
- Contact transmission
- Indirect transmission – vehicle or vector
- Horizontal (vs vertical)
Contact Transmission
- Direct Contact Transmission: person-to-person transmission (touching, kissing, sexual intercourse) without an intermediate object.
- Examples: Hepatitis A, Smallpox, Staphylococcal infections, mononucleosis, sexually transmitted diseases like syphilis or HIV/AIDS.
- Indirect Contact Transmission: the microbe is transferred via a non-living object or fomite, such as towels, eating utensils, thermometers, stethoscopes, bedding, clothes, money, and needles.
- Examples: Herpes simplex virus, Cytomegalovirus, Giardia, Impetigo.
- Droplet Transmission: microbes are spread in mucus droplets that travel short distances (less than 1 meter).
- Examples: respiratory viruses (e.g. influenza, adenovirus, respiratory syncytial virus, human metapneumovirus), Bordetella pertussis, Pneumococci, Diphtheria, and Rubella.
Vehicle Transmission
- Transmission of disease via a medium such as water, food, air, blood, body fluids, and intravenous fluids.
- Waterborne Transmission: usually caused by water contaminated with sewage.
- Airborne Transmission: not to be confused with droplet transmission, is due to inhalation of small pathogens and particles that are suspended in air and can travel long distances.
Antimicrobial Agents
- Antibacterial agents: type of antimicrobial drug used in the treatment and prevention of bacterial infections.
- May either kill (bactericidal) or inhibit the growth of bacteria (bacteriostatic).
- Classified as either broad-spectrum or narrow-spectrum depending on how many types of microorganisms are naturally susceptible to their action.
- Classified depending on their chemical structure and site of action:
- Molecules that inhibit cell wall synthesis.
- Molecules that inhibit the function of the bacterial plasma membrane.
- Molecules that inhibit the synthesis of nucleic acids.
- Molecules that inhibit the synthesis of proteins.
Antiviral Agents
- Major steps targeted by common antiviral agents:
- Attachment and entry: inhibit fusion of viral envelope or attachment to receptor.
- Nucleic acid synthesis: molecules that target viral DNA and RNA polymerases.
- Assembly and budding: inhibit viral proteins needed for virion maturation and/or release.
Antimicrobial Drug Resistance
- Antimicrobial resistance is the ability of a microorganism to survive and multiply in the presence of an antimicrobial agent that would normally inhibit or kill this particular kind of organism.
- Bacterial resistance strategies:
- By preventing the drug from reaching its target by reducing its ability to penetrate the cell.
- By inactivation of the drug via modification or degradation.
- By expulsion of the drug from the cell via general or specific efflux pumps.
- By modification of the drug's target site within the bacteria.
- Viral resistance strategies:
- Results from spontaneous mutations in the viral genome during viral replication.
- Mutations are within the target of the antiviral drug.
- The error-prone polymerase enzyme in RNA viruses causes these viruses to develop resistance more frequently than DNA viruses.
- Special concern during extended therapy for chronic infections (e.g. HIV, HBV, and HCV).
Prevention of Disease Transmission
Immunological Memory
- First exposure to antigen: clonal expansion, memory cells are long-lived, and continue to reproduce.
- Second exposure to antigen: stronger and more rapid response.
Types of Adaptive Immunity
- Adaptive immunity can be:
- Active: natural (exposure to infectious agent) or artificial (vaccination).
- Passive: natural (maternal antibodies) or artificial (injected antibodies).
Artificial Passive Immunisation
- Immunity is transferred by administration of antibodies to a non-immune individual.
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Description
Learn about emerging diseases, their causes, and characteristics. Discover how they can arise from newly identified species, strains, and ecological changes.
