Mode of Transmission in Epidemiology

Study Notes

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

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)

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

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)

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 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 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 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)