Learning Objectives
- Susceptibility of urban areas to epidemics and pandemics of infectious disease can be due to population density, variation in living conditions and healthcare provisions (SHE)
- Contemporary models can project the spread of disease and simulate the effects of possible interventions. Supercomputing has enabled models to predict the relationships between epidemic frequency and location, and factors such as population size, environmental change, persistence and antibiotic resistance (SHE)
- Quarantine measures protect Australia’s agriculture industry and environment against the influx of disease-carrying materials and organisms in the face of increasing global trade and travel (SHE)
- International cooperation and communication are needed to evaluate the risk of the spread of disease, including the emergence of new viral diseases (SHE)
- Interpret a range of scientific and media texts, and evaluate models, processes, claims and conclusions by considering the quality of available evidence; and use reasoning to construct scientific arguments. (SI)
Urban Areas and Infectious Disease
Population Density:
Healthcare Provisions:
- Population density is the number of individuals per square metre
- Population density is higher in urban areas than in rural areas
- People also often congregate and have an even higher population density. E.g. Public transport, markets and leisure activities.
- An easily transmitted infectious disease like influenza can be transmitted easily in urban areas because
- Influenza spreads by indirect, direct and airborne transmission
- An infected person in an urban area will be more often come into close proximity to an uninfected person than one in a rural area
- Urban areas therefore afford more opportunities for transmission of the pathogen
- The moral of the story, the lower the population density the less likely there is to be an epidemic.
- Not all urban areas have the same living conditions.
- In 2017 828 million people were estimated to be living in slums
- Slums are defined as households having one or more of the following:
- lack of access to water protected from outside contamination
- lack of access to sanitation facilities that separate human waste from human contact
- lack of adequate living space (more than three people living in one room of four square meters)
- Infectious disease is more easily spread in urban areas with a larger proportion of people living in slums.
- Why? Lets look at the definition of slums from an epidemiology perspective...
- Lack of uncontaminated water:
- Inhabitants are drinking and washing in contaminated water
- Water is a reservoir for many pathogens e.g. E. coli, Giardia, Hepatitis A, and Salmonella.
- The filtering and disinfecting of household water is believed to be adding about 25 years onto the average Australian's life expectancy!
- Lack of sanitation facilities
- Unable to keep human waste separate from human contact
- Human waste harbours pathogens
- In a modern household this waste is flushed down a toilet without any direct contact and hands a washed with soap to clean off any accidental pathogens.
- Without a toilet or clean running water and soap, pathogens remain in contact with human skin and eventually enter via mucous membranes, digestive tract or wounds.
- Lack of adequate living space
- This is increasing population density on a smaller scale.
- More likely to pass on pathogens via Direct, Indirect or Airborne transmission
- Also more likely to pick-up zoonoses due to the close proximity of pets and productive animals (e.g. household chickens that provide eggs).
- Lack of uncontaminated water:
- While a large portion of many cities is not consisted of slums, people move and an outbreak in slums will eventually result in a spread to other regions of the urban environment.
- The moral of the story
- improved living conditions for the world's poor is in every human's best interest
- the better the living conditions, the less likely there is to be an epidemic.
Healthcare Provisions:
- Healthcare is the provision of medical help in a population for;
- prevention
- cure
- Includes vaccines, medicines, health education
- Access to healthcare in a city is likely to be more freely available than in a rural location because of the cost
- Because healthcare is more readily available in urban areas, people infected with diseases often seek and recieve treatment more quickly, reducing the rate of transmission
- Vaccinations are more readily available in urban areas therefore people are less likely to catch and spread pathogens
- Education programs aimed at reducing spread of pathogens by better hygiene is likely to be effective in urban areas where proximity is a bigger concern.
- The moral of the story: The greater the provision of healthcare, the less likelihood of an epidemic.
Contemporary Models for Managing Spread of Disease
- Mathematical models can project how infectious diseases progress
- Help to show the likely outcome of an epidemic
- Help inform public health interventions like mandatory vaccination, social-distancing and border closures
- Models use basic assumptions or collected statistics along with mathematics to find parameters for various infectious diseases
- Models those parameters to calculate the effects of different interventions
- The modelling can help decide which intervention/s to avoid and which to trial,
- Models can predict future growth patterns.
The Australian government and the world use modelling to deal with the COVID-19 pandemic and have historically used modelling to deal with our permanent influenza pandemic.
Did anyone watch this video on television back in April, 2020?
Quarantining Australia and International Cooperation
Biosecurity has played a critical role in reducing risk and shaping our nation
Australia is one of the few countries in the world to remain free from the world’s most severe pests and diseases.
Geographical isolation has played a key role in maintaining this status
But the barriers of time and distance become less relevant as international travel and trade increases.
Australia has 60 000 kilometres of coastline that exotic pests and diseases could enter throuh.
The Department of Agriculture, Water and the Environment screens, inspects and clears
Part of this process includes shared international resources and intelligence, to help prevent pathogens or pests from making the trip to our shores.
Protects:
Working internationally to mitigate spread of Pathogens:
Source: https://www.agriculture.gov.au/biosecurity/australia
Australia is one of the few countries in the world to remain free from the world’s most severe pests and diseases.
Geographical isolation has played a key role in maintaining this status
But the barriers of time and distance become less relevant as international travel and trade increases.
Australia has 60 000 kilometres of coastline that exotic pests and diseases could enter throuh.
The Department of Agriculture, Water and the Environment screens, inspects and clears
- people
- planes
- mail parcels
- baggage
- boats and ships
- animals
- plants
- cargo containers
Part of this process includes shared international resources and intelligence, to help prevent pathogens or pests from making the trip to our shores.
Protects:
- human health
- $32 billion agricultural industry
- unique, flora and fauna,
- the tourism potential our ecosystems promote
Working internationally to mitigate spread of Pathogens:
- The World Health Organisation (WHO) is a fabulous example of international cooperation
- WHO works worldwide to promote health, keep the world safe, and serve the vulnerable.
- According to WHO's mission statement they:
- focus on primary health care to improve access to quality essential services
- work towards sustainable financing and financial protection
- improve access to essential medicines and health products
- train the health workforce and advise on labour policies
- support people's participation in national health policies
- improve monitoring, data and information.
- WHO have played an enormous role in the international management of COVID-19, however they do not have jurisdiction in any given coutry, thus some nations make their own decisions regarding disease management.
- Have a look at the timeline of WHO's responses to the COVID-19 pandemic: https://www.who.int/news-room/detail/29-06-2020-covidtimeline
Source: https://www.agriculture.gov.au/biosecurity/australia