Mode of Transmission in Epidemiology

Mode of Transmission

Airborne Transmission

• Occurs when pathogens are transmitted through the air
• Pathogens can be in the form of droplet nuclei, dust, or aerosols
• Examples:
  • Influenza
  • Tuberculosis
  • Measles
• Can occur through:
  • Coughing or sneezing
  • Talking or singing
  • Aerosol-generating medical procedures

Vector Transmission

• Occurs when pathogens are transmitted through an intermediate animal or arthropod host (vector)
• Vectors can be:
  • Insects (e.g., mosquitoes, ticks)
  • Arachnids (e.g., mites, spiders)
• Examples:
  • Malaria (mosquito vector)
  • Lyme disease (tick vector)
  • Dengue fever (mosquito vector)

Direct Transmission

• Occurs when pathogens are transmitted through direct contact between an infected individual and a susceptible host
• Can occur through:
  • Skin-to-skin contact
  • Mucous membrane contact
  • Direct contact with infected bodily fluids
• Examples:
  • HIV/AIDS
  • Herpes simplex virus
  • Ringworm

Indirect Transmission

• Occurs when pathogens are transmitted through a contaminated intermediate object or substance
• Can occur through:
  • Contaminated food and water
  • Fomites (e.g., utensils, clothing)
  • Environmental surfaces
• Examples:
  • Food poisoning (e.g., Salmonella, E. coli)
  • Waterborne diseases (e.g., Cholera, Giardiasis)
  • Hospital-acquired infections (e.g., MRSA, C. difficile)

Modes of Transmission

Airborne Transmission

• Airborne transmission occurs when pathogens are transmitted through the air
• Pathogens can exist in the air as droplet nuclei, dust, or aerosols
• Examples of airborne diseases include influenza, tuberculosis, and measles
• Airborne transmission can occur through coughing or sneezing, talking or singing, or aerosol-generating medical procedures

Vector Transmission

• Vector transmission occurs when pathogens are transmitted through an intermediate animal or arthropod host (vector)
• Vectors can include insects (e.g., mosquitoes, ticks) or arachnids (e.g., mites, spiders)
• Examples of vector-borne diseases include malaria (mosquito vector), Lyme disease (tick vector), and dengue fever (mosquito vector)

Direct Transmission

• Direct transmission occurs when pathogens are transmitted through direct contact between an infected individual and a susceptible host
• Direct transmission can occur through skin-to-skin contact, mucous membrane contact, or direct contact with infected bodily fluids
• Examples of diseases spread through direct transmission include HIV/AIDS, herpes simplex virus, and ringworm

Indirect Transmission

• Indirect transmission occurs when pathogens are transmitted through a contaminated intermediate object or substance
• Indirect transmission can occur through contaminated food and water, fomites (e.g., utensils, clothing), or environmental surfaces
• Examples of diseases spread through indirect transmission include food poisoning (e.g., Salmonella, E. coli), waterborne diseases (e.g., Cholera, Giardiasis), and hospital-acquired infections (e.g., MRSA, C. difficile)