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NSWBiologyQuick questions
Module 7: Infectious Disease
Quick questions on Modes of disease transmission: HSC Biology Module 7
12short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is direct transmission?Show answer
The pathogen passes from infected host to new host through physical contact, with no intermediate.
What is indirect transmission?Show answer
The pathogen travels through the air on aerosol droplets or dust particles, sometimes over long distances.
What is plant pathogens?Show answer
The same modes apply in plants, with some plant-specific routes such as transmission via grafting and by aphid vectors (e.g. tobacco mosaic virus).
What is routes?Show answer
Touch (skin, mucous membranes), sexual contact, mother-to-child during birth or breastfeeding, droplet spread over short distances (less than 1 metre).
What is examples?Show answer
HIV (sexual contact, blood-to-blood), glandular fever caused by Epstein-Barr virus (saliva), and tinea (skin-to-skin or shared towels).
What is mechanism?Show answer
Coughing, sneezing or talking produces aerosolised droplets. Smaller droplets (less than 5 micrometres) can remain suspended for hours and travel many metres.
What is classification?Show answer
Direct transmission.
What is implication for control?Show answer
Strategies that interrupt person-to-person contact were the most effective: case isolation, contact tracing, personal protective equipment for healthcare workers, modified burial practices, and ring vaccination.
What is confusing airborne and droplet transmission?Show answer
Droplets larger than 5 micrometres fall within a metre and are classed as direct contact. True airborne pathogens (tuberculosis, measles) travel further on smaller particles.
What is forgetting that vector-borne transmission requires a living vector?Show answer
A contaminated needle is not a vector. Vectors are biological organisms, often with the pathogen undergoing part of its life cycle inside them.
What is generic descriptions?Show answer
"It spreads through the air" is not enough. Specify droplets, aerosols, or contaminated dust, and give the typical distance and duration.
What is ignoring food-borne illness?Show answer
Many students forget that food can be a transmission vehicle, not just water. Salmonella, E. coli O157, and listeria are common food-borne pathogens.