6.1.2 Transmission of Pathogens

• What is a pathogen?

  Biological agent causing disease
• A disease is a specific abnormal condition that affects an organism, impairing its normal functions
• Pathogens cause illness, while disease is the illness itself.
• What are the two main modes of pathogen transmission?

  Direct and indirect
• Indirect transmission involves pathogens spreading through an intermediary such as contaminated surfaces, vectors, or airborne particles
• Match the direct transmission method with an example:

  Physical contact ↔️ Touching an infected person

  Air droplets ↔️ Sneezing

  Vertical transmission ↔️ Mother to child
• The probability of infection through a fomite is inversely proportional to the volume of contact.
• What are the primary methods of direct transmission?

  Physical contact, air droplets, vertical transmission
• Physical contact as a method of direct transmission can lead to skin infections like ringworm
• What does the constant $k$ in the direct transmission infection rate formula represent?


  Infectivity
• A pathogen is the same as a disease.

  False
• Vertical transmission is a direct transmission method that occurs from mother to child.
• Match the indirect transmission method with an example:

  Fomites ↔️ Staphylococcus aureus on surfaces

  Vectors ↔️ Malaria spread by mosquitoes

  Airborne particles ↔️ Tuberculosis spores
• What are the three types of indirect transmission?

  Fomites, vectors, airborne particles
• Pathogens carried by insects or animals from one host to another are spread through vectors
• Pathogens in airborne particles can remain suspended in the air for extended periods.
• What is the primary carrier of pathogens in vector-borne transmission?

  Insects or animals
• In vector-borne transmission, the vector acquires the pathogen by feeding on an infected host
• Biological vectors carry pathogens passively on their body surface.

  False
• Match the term with its description in vector-borne transmission:

  Pathogen concentration ↔️ $C$

  Feeding rate ↔️ $F$

  Transmission efficiency ↔️ $T$
• What type of host is a person bitten by a mosquito in vector-borne transmission?

  Susceptible host
• In vector-borne transmission, the vector bites a susceptible host, transmitting the pathogen
• Mechanical vectors involve pathogens developing within the vector.

  False
• What does the variable $P_{i}$ represent in the equation for probability of infection?


  Probability of infection
• Vector-borne transmission occurs when pathogens spread from an infected host to a susceptible host via vectors
• Airborne transmission involves pathogens suspended in the air and inhaled by susceptible individuals.
• What is the first step in airborne transmission?

  Release of pathogens
• Key factors influencing airborne transmission include air currents, pathogen viability, and environmental conditions
• What is a pathogen?

  Biological agent causing disease
• A disease is an abnormal condition affecting an organism.
• Match the feature with its description in the context of pathogens and diseases:

  Pathogen ↔️ Causative agent

  Disease ↔️ Abnormal condition
• Pathogens are transmitted through two primary modes: direct and indirect
• What is an example of direct transmission through physical contact?

  Touching contaminated surfaces
• Indirect transmission involves the spread of pathogens via an intermediary.
• Match the mode of transmission with its method and example:

  Direct Transmission ↔️ Air droplets ||| Influenza

  Indirect Transmission ↔️ Vectors ||| Malaria
• Direct transmission refers to the spread of pathogens directly from an infected host to a susceptible individual
• What is an example of direct transmission through air droplets?

  Influenza
• Indirect transmission occurs when pathogens are spread through an intermediary
• What is an example of indirect transmission through fomites?

  Influenza on doorknobs
• Pathogens carried by insects or animals are spread through vectors