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*Your ConquerHSC Notes are consistently being revised throughout the 2019 HSC Year to ensure quality!

Week 12 Content

Learning Objective #1 – Investigate and analyse the wide range of interrelated factors involved in limiting local, regional and global spread of a named infectious disease 

Learning Objective #2 – Investigate procedures that can be employed to prevent the spread of disease, including but not limited to: 

  • Hygiene practices 
  • Quarantine 
  • Vaccination, including passive and active immunity 
  • Public health campaigns 
  • Use of pesticides 
  • Genetic engineering 

Learning Objective #3 – Investigate and assess the effectiveness of pharmaceuticals as treatment strategies for the control of infectious disease, for example: 

  • Antivirals 
  • Antibiotics 

Learning Objective #4 – Investigate and evaluate environmental management and quarantine methods used to control an epidemic or pandemic 

Learning Objective #5 – Interpret data relating to the incidence and prevalence of infectious disease in populations, for example: 

  • Mobility of individuals and the portion that are immune or immunised
  • Malaria or Dengue Fever in South East Asia 

Learning Objective #6 – Evaluate historical, culturally diverse and current strategies to predict and control the spread of disease 

Learning Objective #7 – Investigate the contemporary application of Aboriginal protocols in the development of particular medicines and biological materials in Australia and how recognition and protection of Indigenous cultural and intellectual property is important, for example: 

– Bush medicine 

– Smoke bush in Western Australia

NEW HSC Biology Syllabus Video – Prevention, Treatment and Control 

Week 12 Homework Questions

Week 12 Curveball Questions

Week 12 Extension Questions

Solutions to Week 12 Questions

Overview of Week 12 Inquiry Question

Learning Objective #1 - Investigate and analyse the wide range of interrelated factors involved in limited local, regional and global spread of a named infectious disease.

Local spread of Influenza A

Local spread of Influenza A deals with local environments such as schools, hospitals or within one or few suburb(s).

Therefore, depending on the conditions in those environments, the spread of the disease will vary. 

Suburbs with a lot of schools may have higher incidence of Influenza due to the large amount of people that each student comes into contact on a regular basis. 

Similarly, the larger the suburb or local population, the higher the incidence of Influenza may be. 

Alternatively, it is likely that sections of a local area (e.g. suburb/s) with high population density will have higher incidence of Influenza A than sections of the same local area (e.g. same suburb/s) with low population density or interaction.

Regional spread of Influenza A

The spread of Influenza can occur through the use of airplanes. 

This is because it can transport affected and unaffected individuals to different areas or regions in a country. 

  • For instance, someone can take an airplane from Queensland to New South Wales. 
There are many passengers that board regional airlines everyday for various purposes such as work, holiday, etc. This can all result in the transmission of disease, such as Influenza, from one country to another.

However, there are also reasons why, initially, individuals residing in some regions have a disease whereas individual residing other regions do not. Here, we will be dealing with the environmental conditions that affects those regions specifically. 

Another example is that individuals that live in more isolated regions would mean that they will come in contact with less infected individuals compared to those living in the city. This is because the chances of encountering new people everyday is more common for individuals living in highly populated regions than those living in more secluded areas.

Global spread of Influenza A

Similar to how airplanes is a vessel that transports affected & unaffected individuals to different regions in a country, aeroplanes can also take (affected & unaffected) individuals to different parts of the world. 

  • For example, it is possible to board an airplane from Australia to Sweden.

This means that diseases, such as Influenza, can spread from one country to another at a massive scale. 

Furthermore, the disparity in the access to valuable information about methods that can be use prevent or control the spread of disease may vary across countries. Some countries may have limited access to information via the internet or other means of receiving information. For example, the access to information via the internet in third-world countries are considerably limited compared to developed countries. 

Common Factors that apply on a Local, Regional and Global Level for Influenza A:

  • The availability of healthcare facilities including Hospitals, Medical Centres to access vaccination against virus.
  • The increased use of antivirals have rendered to vaccines against Influenza A ineffective such as amantadine and rimantadine were that introduced into the market as antiviral drugs against Influenza. However, they are not longer supplied as the circulating virus is now resistant to those antiviral drugs due to overuse. Therefore, they are no longer effective in controlling the Influenza disease.  
  • The total population of birds in the area may also play a factor in affecting the incidence and/or prevalence of the disease. 
  • NOTE: We will learn the difference between incidence and prevalence in Learning Objective #5 in this week’s notes. Hang in there~

Learning Objective #2 - Investigate procedures that can be employed to prevent the spread of disease, including but not limited to:

- Hygiene practices
- Quarantine
- Vaccination, including passive and active immunity
- Public health campaigns
- Use of pesticides
- Genetic engineering

Hygiene practices

The cleanliness in food, water and personal hygiene practices are important to prevent the spread of, i.e. control, disease. 

This is because pathogens can build up on our bodies or be transferred to healthy individuals via contaminated food and water when consumed.

Personal Hygiene

It is important to wash your hands before eating (e.g. with handwash and water) as there can be harmful microbes on your hands which you can transfer to your food and into your system when contaminated food is consumed. 

Yes, in Week 10 Notes, we talked about how bacteria on our skin can decompose sweat to form acidic conditions that help kill pathogens. However, this is not sufficient to prevent the accumulation of pathogens and which makes showering necessary. You should also wash your hair and shower regularly to prevent the accumulation of pathogens. For instance, the accumulation of pathogens on your skin result skin infections and high possibility of accumulated pathogens entering your mouth (e.g. accidentally brush your arm across your mouth) resulting in diseases like Influenza. 

Gingivitis is the accumulation of bacteria in the mouth which is very brushing teeth and mouthwash are products used to maintain personal hygiene. 

We have explored how Influenza can spread via direct and indirect contact last week. So, if you are sneezing or coughing, you should be covering your nose and mouth using a tissue to prevent the spread of water droplets containing the pathogen. The tissue should also be disposed appropriate to prevent the spread of pathogen. 

Cleanliness of Water
 
Cholera is a disease transmitted via a water-borne bacteria called Vibrio cholerae. Therefore, the spread of contaminated water hosting pathogens can result in many infectious diseases. Since water is necessary for survival, it is important ensure that the water consumed is free of pathogens prior to consumption to prevent and control the spread of disease such as cholera. 
 
Therefore, the appropriate treatment of sewerage water to prevent pollution of waterways as well as the treatment of water prior to supplying to households, shops, etc are necessary to prevent the spread of pathogens and disease. This is why we have sewerage and water treatment plants to ensure that the water exiting the plant compliant with government regulations and requirements.
 
Cleanliness of Food
 

A point that we talked about in ‘Personal Hygiene’ relates to the important of the cleanliness of food. That is, we should wash our hands using hand wash + water prior to handling food. Also, gloves should be worn when handling food and any wounds should be patched up in an appropriate manner (e.g. antiseptic and bandaid)

Eating utensils should be cleaned with detergent and hot water before allowed to be used by another individual to ensure that the tools are free from pathogens. 
 
Chopping boards and other tools used in the preparation of food should be washed in the same manner (using detergent & hot water) before using them to prepare different categories of food to prevent cross contamination. 
 
Food stored in refrigerators should be covered beforehand to prevent being contaminated with pathogens.
 
Food that are frozen should not be thawed in the open to avoid contamination with pathogens. Rather, thawing should be performed in a microwave or inside the refrigerator

Quarantine

By definition, Quarantine can be defined as the act of of individual(s) or species that may potentially be infected from exposure to an infectious pathgeon (e.g. pathogen). 

Quarantine is different to isolation as isolation which is used to refer to the act of separating individual(s) or species, that is has contracted a specific disease (and thus infected with a pathogen), from unaffected individuals or species. 

The Department of Agriculture and Water Resources (DAWR) is a government body that is responsible for preventing pest from crossing the Australian border, thus allowing Australia to be a country relatively free from disease compared to others. 

  • Another reason contributing this benefit is Australia’s geological isolation compared to the rest of the world.
With over Australia’s agriculture industry worth over $60 billion annually, it is critical to ensure that the country should have strict and strong control of pests and diseases that is harmful to the nation’s crops. 
  • The strict and strong quarantine practices is also a reason why Australia’s crops are in high demand as they are seen as free from harmful pests & diseases. 

There is wide range of pathways in which pests or disease can be carried to Australia. Some of these are:

  • Exotic live plant material from airplane passengers, ship cargo, etc.
  • Sand, soil on shoes 
  • Fruits and vegetables
  • Animal or animal products
  • Agricultural equipment
  • The passenger him or herself (perhaps contracted a disease, carrying or infected by pathogen), etc.
 
There are many quarantine strategies that has been put into place, including:
 
Border control: 
  • All humans crossing the Australian border are checked if they are carrying pests or contracted with diseases. These can occur at various areas such as airports, piers and mail exchangers.
  • Hefty fines and jail sentence periods have been stated to dissuade humans carrying or sneaking prohibited items into Australia. 
 
Animal Quarantine: Animals that cross the Australian border are required to be quarantined for forty days to ensure that the animal is not carrying pest or contracted with a disease prior to release. The 10 days allows an appropriate timeframe to allow symptoms of a disease to develop. 
 
Plant Quarantine: Similarly, live plants or fruits that cross the Australian border are also subjected to quarantine for the same reason. During the time of determining whether the plant carries pest or disease, it will be remain in quarantine.
 
If the plant or plant material is dead, it will be subjected to radiation to remove any pests or disease that is present. 
 
Education: As an example, the HSC Biology Syllabus for NSW students incorporates quarantine strategies as a method of controlling pests & diseases.
 
Biosecurity Risk Analysis: This is a form of risk assessment that is performed by DAWR in light of new information of potential risk regarding existing import material. This risk analysis can also be performed when there is a new import category or item that has not been approved in the past.
 
Another note is that all aircrafts entering Australia are disinfected to eliminate vectors such as mosquitoes.

Vaccination, including passive and active immunity

Immunity essentially means a state in which an individual is resistant to being infected by a pathogen and develop the corresponding disease.

Actively acquired immunity exists in two categories, these being Natural or Induced.

For an organism to obtain natural actively acquired immunity, it involves the organism naturally AND unintentionally being exposed to pathogens such as in daily life. The pathogen must trigger the immune response (3rd line of defence), resulting in the production of memory B and T cells. 

  • This allows a secondary immune response to be initiated when the individual is exposed to the same pathogen. Recall from Week 9 Notes that secondary immune response is much faster than primary immune response due to the presence of memory B and T cells that are already present and circulating in the lymph and blood. 
  • Also, more antibodies, specific to the pathogen, are produced in the secondary immune response than in the primary immune response.

Vaccines are a form of induced actively acquired immunity in which an individual can obtain. This involved individuals artificially AND unintentionally being exposed to pathogens. Vaccines are essentially pathogens that are either weakened or dead, resulting it to be harmless. 

  • These vaccines can be provided to the individual orally or via injection.
  • NOTE: Remember Robert Koch? Well, the pathogen contained in the vaccines will be the one causing the disease in which the individual want to develop immunity to. 
As these weakened or dead microbes contain the antigen, it will remain to trigger an immune response when introduced into the individual’s blood system where the antigen will travel to the lymph nodes and encounter the B and T lymphocytes. As a consequence, memory B and T cells are produced whereby the mechanisms in how memory B and T cells are produced were already discussed in Week 9’s Notes. 

This means that, in the future, if the vaccinated individual encounters the same pathogen, it will be immune to the disease in which the pathogen causes and its symptoms. 

Also a secondary immune response will be triggered in the vaccinated individual rather than a primary immune response due to the production of memory B and T cells as a result of the vaccine. 

  • NOTE: Immunity will only occur if the vaccine has high efficacy (ability to produce desired result) or is highly effective against the pathogen. 
  • NOTE: Remember we have talked about antibiotic resistance, mutation of viruses, etc? Well, those can all lower the efficacy of the vaccine. 
  • NOTE: Also memory B and T cells that are produced as a result of the vaccine do not survive forever. 

Passively acquired immunity can take place in two forms: Natural or Induced.

In natural passively acquired immunity, it involves the transfer of antibodies from mother to baby such as diffusion through the placenta. 

  • Alternatively, it can also occur after birth where the mother breast feeds the baby where breast milk contains antibodies.
Induced passively acquired immunity involves the injection of antibodies that is produced from one host into another. 

Both forms of passively acquired immunity is short-lived, i.e. at  a maximum of several months. This is because the introduction of antibodies do not result in the production of memory T or B cells. 

  • Recall from Week 9 Notes that memory T and B cells can remain in circulation in the lymph & blood for many years.

Public health campaigns

Public Health Campaigns are advertised and/or provided to the public to convey a health message and generate a desire from the target audience.

One example of a public health campaign are the government regulations established to:

  • Convey the appropriate requirements of potable (drinkable) water exiting the water treatment plant that is supplied to households and factories. This supports the access to clean water which help prevent diseases caused by water-borne pathogens.
  • Conveying the appropriate treatment requirement and disposal methods of household and urban sewerage waste. 
These two methods can prevent individuals come being infected with pathogen and contracting the disease.
  • Conveying and establishing standardised methods pertaining the storage, handling and cooking of food in restaurants. 
  • Conveying and establishing standardised methods regarding sterilising medical equipment that is used between patients in hospitals. 
These procedures prevent individuals having pathogens in their hood due to restaurant workers not following standardised procedures. Also, the sterilisation of equipment prevents pathogens to be transferred from one host to another which can cause diseases like AIDS and prion diseases like CJD.

 

There are screen programs advertised and offered by the government that are free of charge between a certain age to allow early detection of potential disease such as Breast Cancer and Bowel Cancer. By detecting signs of disease early, it would lower the risk of contracting the disease or easier cure. 

There are also many educational campaigns that are announced and run by non-profit-organisations such as the SunSmart program that is funded by Cancer Council Victoria and VicHealth. It educates public about:

  • How they can prevent skin cancer (e.g. Slip, Slop, Slap, Seek, Slide) & recommended products 
  • How to individuals can detect early signs of skin cancer 
  • Recommended treatments for skin cancer

Use of pesticides

Pesticides are chemicals and a broad term that encompass insecticides, fungicides and herbicides. 

Respectively, they are used to eliminate insects (vectors), fungi disease and weeds. 

The DDT insecticide was used kill Anopheles Mosquito that is a vector for the malaria disease as it carries the plasmodium pathogen. However, as expected due to evolution, resistance has developed in the Anopheles Mosquito population due to overuse of the insecticide. 

Insecticide that contain carbamates and pyrethroids are used to spread mosquito nets to avoid mosquito bites at night and kill mosquito. This therefore can prevent the spread of the malaria disease.

These pesticides can also be added into irrigation water which will be come into contact with crops and kill vectors. 

However, due to the inevitable development of resistance by the pesticides, pesticides’ negative impact on human health and the environment, alternative solutions are currently being researched. 

Genetic engineering

Genetic engineering such as using recombinant DNA technology to produce transgenic species is a popular measured used by farmers in preventing and controlling the spread of disease through a species population. 

For example, in Module 6, we have talked about how Bt Corn and Bt Cotton are transgenic crops are capable of manufacturing insecticide that kills pests that it makes contact with that may be carrying a pathogen. 

However, the problem with the vectors (e.g. insects) developing resistance to the insecticides remain to be inevitable in the upcoming future. 

There are also many ethical issues that are surrounding the topic of genetic engineering that we have explored in Module 6. 

There are also benefits in producing transgenic animals which produces proteins that grants resistance against diseases which we can extract. For example:

  • Alpha-Glucosidase can be extracted from transgenic rabbit which is can be used to gain resistant against Pompe’s disease. This disease is a metabolic disorder leading to damage dealt to nerve cells in body.
  • Antithrombin III can be obtained from transgenic goat which can subsequently be employed to defend against thrombosis (clotting of blood without bleeding). 
  • Antibodies obtained from transgenic mice is able to be used to fight against corona virus that is responsible the TGE disease in pigs that causes excessive puking and diarrhoea. 

Learning Objective #3 - Investigate and assess the effectiveness of pharmaceuticals as treatment strategies for the control of infectious disease, for example:

- Antivirals
- Antibiotics

Antibiotics

Robert Koch found out in 1882 that Tuberculosis is caused by the pathogen, Mycobacterium tuberculosis. However, isolation of an extract of the pathogen and injecting into individuals not yield the results which vaccines would hoped to yield. 

The use of the streptomycin was responsible for lowering 25,000 annual deaths in Great Britain due to tuberculosis after world war two to few hundred by the 1970s.

The success in reducing the cases people having tuberculosis led to the closure of many sanatoria establishments which saved a lot of government funding. 

The success at Africa led to officials announcing the high possibility of reducing the incidence of tuberculosis to zero in 1960. 

However, the use of antibiotic has side effects that included deafness, vertigo and nausea. 

Due to antibiotic resistance to the drug, the incidence of tuberculosis began to increase in the late 1970s rather than declining. 

Currently, the disease is responsible for the annual death of over one million people globally and approximately one fourth of the global population is currently affected by the pathogen responsible for the disease. However, fortunately, only approximately 5% are experiencing the symptoms. 

In short, the effectiveness of the antibiotic was only short-term due to rapid increase in antibiotic resistance by the pathogen Mycobacterium tuberculosis responsible for Tuberculosis. 

 

How do Antibiotics work?

Antibiotics are only used to treat bacterial infection whereas antiviral drugs are used to treat viral infection (infections caused by viruses).

Antimalarial drugs that we have explored last week are used to treat malaria specifically. 

Antibiotics affect the metabolic activities of bacteria which does not exist in viruses.  Specifically, antibiotics stop cell wall synthesis and protein synthesis occurring in bacteria.

The pause in protein synthesis result in the bacteria of the new generation not having the required protein or enzymes to invade cells.

The destruction of the cell wall makes the bacteria susceptible to bursting due to osmotic pressure differences between external environment and bacteria’s internal environment.

Unlike antibiotics that kills bacteria, antivirals usually don’t kill the virus but rather stop the virus’s development.

NEW antibiotic that DOES NOT cause pathogen resistance?!

Yes! The name of this antibiotic is Teixobactin.

It may able to kill bacteria without causing the bacteria to develop antibiotic resistance O_O’

So far, the antibiotic is able to treat various diseases such as the golden staph disease which is resistant to many antibiotics. However, the pathogen that is killed with teixobactin does not appear to develop any resistance to it. 

It is currently not certain as to why this is the case. Teixobactin is therefore a new class of antibiotics that is currently being researched. 

Antivirals

The effectiveness of the anti-viral drug in treating Influenza was been mixed.

The recommended antiviral by global public health agencies supplied to consumers to treat, prevent and control Influenza are Oseltamivir and Zanamivir.

A 2014 case study that involved over using 24,000 patients’ data has revealed that:

  • The incidence of influenza spreading from an infected family member to unaffected members are reduced in households.
  • The recovery time from Influenza between the adult and children that took and did not take Oseltamivir had a difference of less than one day (6.3 days compared to 7 days). 
  • Comparatively, the recovery time for patients supplied with and not supplied with Zanamivir was from 6.6 days to 6 days.
  • The antiviral did not cut down the amount of people that required hospitalisation. 

However, an alternative study performed by ‘The Lancet’ with 4328 participants in 2015 revealed that patients supplied with antiviral provided a 21% faster recovery time compared to patients without. Also it reduced amount of hospitalisation required.  

Both drugs did not lower the severity of ear infection or sinus infections. 

Zanamivir decreased the incidence of bronchitis while Oseltamivir did not. 

Both drugs increased puking, nausea and headache symptoms in patients. However, the incidence of diarrhoea decrease.

Similar to antibiotic resistance, viruses can also develop resistance to antiviral drugs. As a result, the drugs would be ineffective in lowering the duration of the disease (control) and reduce the symptoms of disease. Therefore, the drugs would be ineffective in controlling the disease. 

  • For instance, amantadine and rimantadine were introduced into the market before Oseltamivir and Zanamivir as antiviral drugs against Influenza. However, they are not longer supplied in the USA as the circulating virus is now resistant to those antiviral drugs. Therefore, they are no longer effective in controlling the Influenza disease. 
  • This will also be the future of Oseltamivir and Zanamivir as virus mutate at a moderate to high rate, resulting the virus to develop resistance to existing antiviral drugs.

As, from the above case study, there are mixed results for Oseltamivir and Zanamivir in controlling the disease. Furthermore, there are many side-effects that we have explored which makes the drug potentially  dangerous for patients. 

Overall, more clinical trials must be performed to determine the effectiveness of the antiviral drugs in controlling the disease, eliminate mixed results and arrive to decisive answer about whether the drug is effective at controlling the disease (e.g. lowering the duration of disease).

Learning Objective #4 - Investigate and evaluate environmental management and quarantine methods used to control an epidemic or pandemic

Environmental Management to Control Epidemic

According to the World Health Organisation (WHO),

Environmental management seeks to change the environment in order to prevent OR minimise vector propagation and human contact with the vector-pathogen by destroying, altering, removing or recycling non-essential containers that provide egg/ larval/ pupal habitats”

There are three main types of environmental management which the World Health Organisation outlined to control Dungue Fever:

  • Environmental modification  Long-lasting physical transformations to reduce vector larval habitats. For example:
    • Installation of a reliable piped water supply to communities, including household connections.
  • Environmental manipulation  Temporary changes to vector habitats involving the management of “essential” containers, such as:
    • Frequent emptying and cleaning by scrubbing of water-storage vessels, flower vases and desert room coolers.
    • Cleaning of gutters.
    • Sheltering stored tyres from rainfall.
    • Recycling or proper disposal of discarded containers and tyres.
    • Management of plants close to homes that collect water in the leaf axils.
  • Changes to human habitation or behaviour  Actions to reduce human coming into contact with vector. These include:
    • Installing mosquito screening on windows, doors and other entry points.
    • Using mosquito nets while sleeping during daytime.

Let’s now have a look at the main vectors that are responsible for epidemics. 

  • Mosquitoes
  • Non-biting flies
  • Lice
  • Mites
  • Rodents (Rats)
When we are evaluating the environmental management methods and strategies used to control vector propagation and human contact with vectors carrying the pathogens, there is consideration place in the balance between effectiveness as well as economically acceptability in terms of cost. 
 
At the end, the purpose of environmental management in controlling vectors carrying pathogens is to keep the vectors’ level at an amount that is capable of causing an epidemic. 
 
Let’s take a look at some specific examples used in Ebola Treatment Centres:
 
Isolation Camp or Treatment Centre organisation
  • The treatment centre should have appropriate space to accomodate number of affected people residing inside. As per the WHO guidelines, there should be 4-5 square metre of shelter space per affected individual.
  • The centre should also have pavements, clean water supply, shelters, health services, education centres, food storage and market place. 
  • Therefore, the camp could have sugar (e.g. marshmallows), pikachu stuff animals, etc. 
  •  Out of these factors, shelter would probably be the most important as it offers the affected people protection from changing climatic conditions such as heavy rain, thunderstorms, etc. 
  • The organisation of food storage in the treatment centre could be stored in warehouses that are shielded from vectors such as rats, insects and birds. The food containers should also be sealed with lids to prevent contamination or being in contact with vectors.
 
Disposal of human faeces 
  • There should be one toilet cubicle or facilitate per every 20 individual and they should be separated according to gender.
  • These facilitates should also be located at a minimum distance of 50 metres from any treatment ward or shelter. 
  • The focus should also be ensuring that the quality of the toilet facilitates are being maintained and is up to appropriate standards in minimising the proliferation of pathogens and transmission of diseases via human faeces. 
  • NOTE: The quality of showers should also be maintained. 
 
Other organic waste management 
  • Food waste should be disposed in a controlled manner to avoid attracting vectors such as rats, establishing breeding sites for flies, and minimise pollution local waterways. 
  • Garbage bins should be abundant in the treatment centre as well as being located close to shelter. This allows and encourages easy disposal of waste conveniently. 
  •  Appropriate burial sites for dead bodies should be available.
 
Wastewater management and site drainage
  • Wastewater can be produced via multiple channels such as from the showers, toilets, medical wastewater, etc. 
  • Sometimes, there are medical wastewater is disposed in cesspits or urine in pit latrines. In such cases, polystyrene can be poured into the pits to prevent them becoming establishment of mosquitoes breeding site. 
  • This is very effective as studies have shown such use of polystyrene reduced the mosquito population by over 95% after using such polymer (polystyrene). 

Quarantine Methods Used to Control Epidemic

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Learning Objective #5 - Interpret data relating to the incidence and prevalence of infectious disease in populations, for example:

- Mobility of individuals and the portion that are immune or immunised
- Malaria or Dengue Fever in South East Asia

This learning objective is about interpreting data relating to the incidence and prevalence of infectious diseases in a population. 

This is a pretty generic question and so there are a range of ways in which data can be displayed on your exam paper during HSC day.

For example, the data may be presented in a:

  • Column Graph
  • Line Graph
  • Bar Graph
  • Table

The two common terms in the learning objective are ‘incidence’ and ‘prevalence’. 

Prevalence means the total amount of individuals affected by the particular disease in a given population and time. 
  • Prevalence Rate = Total instance (old + new cases) of disease in population at a given point in time / total number of individuals in population at risk

NOTE: Careful considerations need to determine which individual should be included as the ‘total population at risk’. For instance, if we are dealing with Alzheimers, it probably not be appropriate to count the children population as they are NOT at risk of having the disease. 

Incidence is the number of new individuals affected by the disease in the same population in a given point in time. 

  • Incidence Rate = New instance of disease in population / Duration or period of time in which individuals in population is at risk of getting disease.

Limitations of using Incidence Rate:

  • This rate may differ when measured across different time periods as even distribution is assumed, thus, the formula assumes constant rate.
  • To improve the above formula for incidence rate, we can use:
  • Modified Incidence Rate = New instance of disease in given time period / Number of individuals at risk of getting disease during that time period. 
NOTE: Morbidity rate refers to the occurrence of the disease which includes both incidence and prevalence rates. 

Learning Objective #6 - Evaluate historical, culturally diverse and current strategies to predict and control the spread of disease.

The work of Louis Pasteur & Robert Koch in predicting the spread of disease in the mid 1800s was already discussed in Week 9 Notes. 

So, we will not delve into that. If necessary, you can revise them at:

https://www.conquerhsc.com/hsc-biology-syllabus-notes-module-7-infectious-disease/

Instead, we will explore few more examples that you can incorporate in your response for higher mark questions. 

In 1854, John Snow successfully used a ‘spot map’ to identify the relationship between people affected with cholera and contact with polluted sewage water from a local river. 

  • Before then, it was believed that cholera is due to contact with air of bad smell.
  • The spot map comprised of location of families infected with cholera in contact various water pumps. It was identified that Broad Street Pump was responsible for the disease. 
In the late 1890s, vaccines were manufactured to control (and prevent) the transmission of disease such as cholera and typhoid fever. 
 
The success of vaccines pave the large efforts put into developing vaccines to prevent and treat HIV and malaria. So far, there is no vaccines that is proven to successfully prevent or treat HIV and the only vaccine to prevent malaria has low successful rate or low efficacy.
 

Different cultures would have different traditional methods in treating diseases passed down through generations. 

  • For example, the Aboriginal People of Australia have acquired extension knowledge in using native Australian flora to treat diseases. 
  • DIY treatment (e.g. Herbal, saltwater, etc) vs pharmaceutical drugs to treat Influenza. 
 
Current:
  • Ensuring, monitoring and supply of clean water supply.
  • Appropriate handling and treatment of sewerage waste. 
  • Antibiotics & Anti-viral drugs.
  • Vaccines
  • Public Health Campaigns – including the importance of personal hygiene. 
  • Global Health Maps
  • Quarantine 
  • Isolation – In hospitals – Tuberculosis patients. 
  • Pesticides
  • Genetic Engineering

Learning Objective #7 - Investigate the contemporary application of Aboriginal protocols in the development of particular medicines and biological materials in Australia and how recognition and protection of Indigenous cultural and intellectual property is important, for example:

- Bush medicine
- Smoke bush in South Australia

Bush Medicine

The Aboriginal Peoples demonstrated their technique or protocols (method) of using substances in specific fruits and plants to meet their specific medicinal needs.

By using analytical techniques such as titration, chemists are able to determine the nature of various substances that are present in fruits and plants used by Aboriginal People in Australia. 

The Davidson plum is a natural Australian fruit that approximately 100 times more ascorbic acid (vitamin C) than contained in an orange. For such reason, it has a very sour taste due to the high concentration of acid. Aboriginal and Torres Strait Islander Peoples consumed the Davidson plum as way to boost their body’s nutrient level which reduced their chance of having scurvy disease.

When exposed to water, the soap’s tree leaves is able to lather or produce a soap solution that have antibacterial properties and thus act as an antiseptic. The reason for this is that the leaves contain saponin acid which has the ability to suppress bacteria growth. Aboriginal and Torres Strait Islander Peoples used the soap tree leaves as a way to heal cuts on their skin. 

Aboriginal and Torres Strait Islander Peoples also used yellow ochre (hydrated iron hydroxide) to treat stomach upsets. The chemistry behind is that the yellow ochre is basic and thus can react and neutralise with any excess hydrochloric acid in the stomach. This served as a way for Aboriginal and Torres Strait Islander People to remove any heartburns or stomach upsets. The yellow ochre has base similar to antacids which is an example of medicine used in everyday life to treat stomach upsets.

The Grey Mangroves are used to treat stingray injury by preventing infection and neutralise the mildly acidic stingray venom. This is done by smashing the Grey Mangroves’s leaves and adding water to create a mixture that is a base which can be applied to the wound caused by the stingray.

Experimental results obtained from trials performed by the American National Cancer Institute revealed that the smokebush comprise of a molecule called conocurovone that is capable of killing the HIV virus that can be used to cure AIDS.

Intellectual Rights of Indigenous Australians

As Aboriginal people have been residing in Australia for over 65,000 years, they have acquired understanding of the medicinal or healing properties of bush medicine through interaction. It is this process of interacting with natural resources that led to the “Indigenous Ecological Knowledge” as labelled by the Australian Government.

The Aboriginal People’s knowledge of the natural Australian ecology such as the medicinal properties of bush medicine is categorised under the “Indigenous Cultural and Intellectual Property” by the Australian Government.

Biotechnology companies that is performing research on creating plant-derived medicines may use books that contains records of Aboriginal People’s method of using various traditional techniques and knowledge on using various flora as medicine to treat diseases that are passed down over many generations. 

Also, Aboriginal People are insisting that scientists working for biotechnology companies are submitting their patents claim for their new plant-derived medicines which contains information sourced from them directly during the research and development process. 

The process of submitting a patent claim is expensive and may not be affordable for individuals such as a single Aboriginal person. Comparatively, biotechnology companies have access to capital from investments, allowing them to have enough funding to submit a patent claim. As a result, the Aboriginal People may not receive the recognition or monetary benefit that they otherwise could have.

The Commonwealth Copyright Act also contains a ‘loophole’ in the case of intellectual property. This is because the traditional knowledge of Aboriginal people on the medicinal properties of native Australian flora is, for the most part, passed down to generation verbally. Thus,  there is no written or visual proof of such traditional knowledge to satisfy the criteria of the copyright protection in the Act. 

This means that these traditional knowledge can be used by researchers working at biotechnology companies without the consent of Aboriginal People. 

Furthermore, copyright protection is not indefinite but, rather, it only exist until 70 years after the death of the author which the knowledge is protected under. 

The old books written by Aboriginal People often do not have author names and this makes it difficult to attribute copyright protection to a specific person.

Therefore, legalisation must be established to protect the intellectual property of Aboriginal People’s traditional knowledge of Australia’s ecology. This is a matter dealing with ensuring fairness and equity.

For example, the Plant Breeders Rights Act 1994, allows Aboriginal People to have a permanent right oppose the production or sale of the plant (including seeds) that belongs to the Aboriginal People through historical document of discovery. However, these documentations are not reflective of the full collection of flora belonging to the Aboriginal People and, thus, many biotechnological companies are granted rights to indigenous plants. As a result, there is a current scenario where Aboriginal People are unable to access such plants without approval from the party holding the right. 

 

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