Year 9 Science · Unit 1 · Lesson 3

Disease Transmission

Challenge Worksheet

Name

Date

Class

Learning Goals

Apply transmission route knowledge to a novel real-world scenario involving multiple diseases.
Evaluate how different transmission routes affect the design of public health responses.
Justify why breaking specific links in the chain of infection is more or less effective for different diseases.

Go Deeper

What if…?

Scenario

You are a public health officer in a regional Australian town. In the same week, you receive reports of three separate disease outbreaks: (1) several students at the local school have influenza, spread through respiratory droplets; (2) fifteen residents have gastroenteritis traced to a contaminated tap in the town water supply, likely giardia (a protozoan); and (3) two travellers returning from northern Queensland have been diagnosed with Ross River virus, spread by mosquito bite.

Box 1 For each of the three outbreaks, name the transmission route and identify the single most effective intervention to break the chain of infection. Explain why that intervention works for that specific route, and why it would NOT work for the other two outbreaks.

Challenge 4 marks

Box 2 The influenza outbreak is spreading rapidly through the school. Compare how the spread of influenza (airborne) would differ from the spread of giardia (waterborne) in this school setting. Which outbreak would be harder to contain once it has started, and why?

Challenge 3 marks

Box 3 A community member suggests: "We should just tell everyone to wash their hands more, that will fix all three outbreaks." Using your knowledge of transmission routes, evaluate this suggestion. For which outbreak(s) would handwashing be effective, and why would it be insufficient for the other(s)?

Challenge 3 marks

Show What You Know

1. In 2022, monkeypox spread in Australia through direct skin-to-skin contact (a contact transmission route), not airborne droplets. Explain why contact tracing was a more useful control strategy for monkeypox than it would be for measles (airborne transmission). Include specific reference to how each disease's transmission route affects the pattern of spread and the ability to identify close contacts.

Challenge 4 marks

2. The 2018 Australian listeria outbreak was traced to contaminated rockmelon via a foodborne route and killed seven people. Despite this, it never became an epidemic. Explain why foodborne outbreaks tend to be self-limiting (they stop spreading) once the contaminated food source is identified and removed, whereas airborne diseases continue spreading even after the original source is removed.

Challenge 3 marks

Wrap Up

In one sentence, what was the main idea of this lesson?