Infectious diseases

• What is the difference between infectious diseases and non-infectious diseases?

  Infectious diseases are caused by pathogens and can be transmitted, while non-infectious diseases are genetic or lifestyle-related.
• What are the types of pathogens?

  Prions, viruses, bacteria, fungi, protists, and parasites.
• What are virulence factors that aid in pathogenesis?


  Adherence factors, invasion factors, capsules, toxins, and lifecycle changes.
• What are the modes of disease transmission?

  Direct contact, contact with body fluids, contaminated food, water, and disease-specific vectors.
• How do pathogens stimulate host immune responses?

  By causing physical and chemical changes in host cells through foreign chemicals, toxins, and recognition of self and non-self.
• What is an antigen?

  A molecule or molecular structure on a pathogen that stimulates an immune response.
• What types of immune responses do plants and animals have?

  Plants and animals have innate immune responses, while vertebrates also have adaptive immune responses.
• What are the differences between specific and non-specific defense mechanisms?

  • Specific defense mechanism: adaptive responses targeting specific pathogens.
  • Non-specific defense mechanism: innate immunity against all pathogens.
• What are examples of physical defense strategies in plants?

  Leaf’s waxy cuticle and leaf structure.
• What are examples of chemical defense strategies in plants?

  Plant defensins and production of toxins.
• What comprises the innate immune response in vertebrates?

  Surface barriers, inflammation, and the complement system.
• What are surface barriers in the innate immune response?

  Shedding of old skin cells, mucus containing lysozyme, and cilia sweeping mucus.
• What triggers inflammation in the innate immune response?

  Histamines trigger inflammation in response to pathogens.
• What is the complement system?

  A group of plasma proteins that enhance the actions of antibodies and immune cells.
• How does the transmission of disease occur?

  Through the transfer of pathogens between organisms.
• What factors affect immunity?

  Population density, travel, hygiene, herd immunity, transmission mechanism, and pathogen category.
• What is the difference between an epidemic and a pandemic?

  An epidemic affects a local population, while a pandemic spreads globally.
• What is herd immunity?


  When a sufficient number of people in a community are immune, reducing disease transmission.
• What is direct contact transmission?

  Transmission through physical contact between an infected and a susceptible person.
• What is indirect contact transmission?

  Transmission without direct human-to-human contact, such as airborne transmission.
• What are fomites?


  Contaminated objects that can transmit disease.
• What is the difference between living and non-living pathogens?

  Living pathogens require water and nutrients, while non-living pathogens do not.
• What does R0 measure?

  R0 measures the number of secondary infections produced by a single case of infection.
• What does an R0 value greater than 1 indicate?

  Transmission is increasing, and an outbreak is possible.
• What factors affect R0?

  Length of infectious period, probability of transmission, rate of new contacts, population density, and virulence levels.
• What are strategies to control the spread of disease?

  • Personal hygiene measures: handwashing, not sneezing on others, cleaning items, disposing of tissues, using masks.
  • Community level: contact tracing, quarantine, school/workplace closures, reducing mass gatherings, temperature screening, travel restrictions.
• What is the inflammatory response?

  The inflammatory response involves prostaglandins, vasodilation, and phagocytes.
• What role do phagocytes play in the immune response?

  Phagocytes engulf and destroy pathogens.
• What are prostaglandins?


  Molecules that mediate increased blood flow, attract white blood cells, and raise body temperature.
• What is vasodilation?


  The dilation of capillaries to allow fluid and white blood cells to accumulate at the site of infection.
• What triggers the release of histamines?

  Mast cells trigger the release of histamines during an inflammatory response.
• What are natural killer cells?

  A type of white blood cell that destroys virus-infected and cancer cells without prior activation.
• What is apoptosis?


  Cell death.
• What is the major histocompatibility complex (MHC)?

  MHC proteins are unique to individuals and found on the surface of cells.
• What is self-tolerance?


  Self-tolerance is the lack of response to self-cells.
• What triggers an immune response?

  Foreign cells with non-self-antigens trigger an immune response.
• What are antigen-presenting cells?

  Some phagocytes that present foreign antigens to trigger adaptive immunity.
• What are the adaptive immune responses in vertebrates?

  • Humoral response: production of antibodies by B lymphocytes.
  • Cell-mediated response: involves T lymphocytes.
  • Memory cells are produced in both responses.
• What is adaptive/acquired immunity?


  Immunity acquired via natural exposure to a pathogen or through vaccines that form a specific response.
• What is an antibody?

  A Y-shaped protein produced in response to a pathogen that binds to a specific antigen.