Disease Transmission
Organisms that cause disease are also called this.
Pathogens
Double point bonus: what are 3 different types of pathogens?
The chain of infection includes the pathogen/source, a reservoir, a mode of transmission, and what other 3 links?
means of exit, means of entry, and susceptible host
This type of immunity is achieved when most people in a population are vaccinated.
Herd Immunity
This process involves identifying people who may have come into contact with an infected person.
Contact Tracing
Double Point Bonus: Describe the two types of contact tracing
This international organisation coordinates responses to global health emergencies.
World Health Organisation
This pathogen created a pandemic in 1918 that killed millions worldwide.
Influenza
Double Point Bonus: What type of pathogen is Influenza?
This type of disease transmission occurs when an infected person sneezes or coughs, and droplets land on another person.
Direct Transmission: Droplet Transmission
What is a reservoir of disease?
The natural habitat where an infectious agent, such as a virus or bacterium, lives, grows, and multiplies before it can be transmitted to a susceptible host.
Vaccines train this system to recognize and fight pathogens.
Adaptive Immune System
Double Point Bonus: Do vaccines give active or passive immunity?
What is the difference between isolation and quarantine?
Isolation: This is when a person (or animal) who is already sick or confirmed to have an infectious disease is separated from healthy people. The goal is to prevent them from spreading the disease to others.
Quarantine: This is when a person (or animal) who may have been exposed to a disease but is not yet sick is separated from others. The goal is to see if they develop symptoms and prevent potential spread.
The CDC is an organisation from this country.
The USA
Ebola outbreaks primarily occur on this continent.
Africa
Double Point Bonus: What is the mode of transmission for ebola?
Give an example of vector borne transmission
Mosquitoes: malaria, ross river virus, dengue fever
Ticks: Lyme
Fleas: Plague
Bats: rabies
Hand washing primarily breaks this link in the chain of infection.
mode of transmission
Double Point Bonus: Give another example of how to break the chain at this link.
Name one environmental strategy used to prevent disease spread in communities.
e.g. water treatment, proper waste disposal, or disinfecting surfaces
Closing schools, limiting gatherings, or cancelling events to restrict movement of people are examples of this type of public health measure.
Social distancing
Double point bonus: what is the minimum distance that the government recommended for social distancing during covid?
What is a pandemic preparedness plan?
plan that helps countries prepare for and respond to pandemics.
Double Point Bonus: Give an example of one way Australia could have improved our pandemic response during COVID19 based on your understanding of disease control.
This disease was eradicated during the 20th century after a global vaccination program.
Small Pox
Give an example of a reservoir of disease
Animals: Bats, pigs, chickens, monkeys, humans
Environment: water, soil, food
Using personal protective equipment (PPE) can break the chain at which link?
Means of entry
How are education campaigns helpful in preventing the spread of disease? Give a specific example.
Education campaigns increase awareness and knowledge about how diseases spread and how to prevent infection. They encourage people to adopt healthy behaviours, such as handwashing, mask-wearing, vaccination, or avoiding crowded places. By changing individual behaviour across a population, education campaigns can reduce the overall transmission of a disease.
E.g. During the COVID-19 pandemic, public health campaigns promoted hand hygiene, mask-wearing, social distancing, and vaccination. These campaigns helped slow the spread of the virus, particularly before vaccines were widely available.
Name one challenge of contact tracing in large populations.
E.g. underreporting, delayed testing, asymptomatic carriers, or lack of cooperation.
Describe one benefit and one limitation of closing borders during a pandemic.
Benefits:
- Slows the importation of new cases from other
countries.
- Gives healthcare systems more time to prepare
and respond
- Reduces the risk of overwhelming hospitals and
public health resources
- Provides time to implement domestic control
measures (testing, contact tracing, vaccination)
- Can protect vulnerable populations from early
exposure
Limitations:
- Disrupts trade and tourism, harming the economy
- Limits the movement of essential workers and
supplies
- May not fully prevent disease if infected people
enter undetected
- Can create social and political tensions with other
countries
- Prolonged closures can impact mental health and
access to services for citizens
John Snow is considered a founder of modern epidemiology due to his 1854 investigation of an outbreak of this disease.
Cholera
Double Point Bonus: How did John Snow show that Cholera was a waterborne disease rather than a miasma cloud as was commonly believed at the time?
Name one factor that can increase the likelihood of a disease spreading in a community.
population density, poor hygiene, lack of vaccination, or international travel
Give an example of a way to break the chain of infection at the source.
Vaccination programs
This number, often called R0, indicates how many people (on average) one infected person will pass a disease to.
Using this number, scientists can calculate the proportion of the population that needs to be vaccinated to achieve herd immunity (Herd Immunity Threshold = 1 – 1/R₀).
If R0=3 what is the proportion of the population that needs vaccination to achieve herd immunity?
2/3 or ~67% of people in the population
Double Point Bonus: What if R0=5?
Name one challenge governments face when implementing quarantine during a pandemic.
economic impact, public compliance, or mental health effects
Name one challenge global organisations face when coordinating outbreak responses.
Differing national policies, funding limitations, or communication delays
Define an outbreak, an epidemic, and a pandemic. Explain one contributing factor that led to Covid-19 becoming a global pandemic.
Outbreak: An outbreak is the sudden occurrence of a disease in a specific population or area. E.g.: A few cases of food poisoning at a school.
Epidemic:An epidemic occurs when the number of cases of a disease rises significantly above what is normally expected in a community or region. E.g.: Seasonal flu affecting several cities or a country.
Pandemic: A pandemic is an epidemic that has spread across multiple countries or continents, affecting a large portion of the global population.
Contributing factor for COVID-19 becoming a pandemic:
High transmissibility of the virus (it spreads easily between people - droplet and airborne transmission)
Presence of asymptomatic carriers (people can spread it without showing symptoms)
International travel and global connectivity (rapid movement of people between countries)
Delays in detection and reporting of initial cases
Urban population density (crowded cities facilitated faster spread)
Limited early testing and contact tracing capacity in some countries
Global trade and supply chains increasing human contact and movement