MODULE 7: INFECTIOUS DISEASE IQ1: How are diseases transmitted? 1.1 describe a variety of infectious diseases caused by pathogens, including microorganisms, macroorganisms and non-cellular pathogens, and collect data and information relating to disease transmission, including: - classifying different pathogens that cause disease in plants and animals

● A pathogen is any organism or infectious agent capable of causing disease by: releasing toxins, damaging tissue or competing for nutrients.

● Virulence is a pathogen or microbe’s ability to damage a host. TYPES OF PATHOGENS Pathogen Examples of disease

caused Features of group

Viroid (Plant only) ● Apple scar skin ● Potato spindle

tubers

● Non-cellular, similar to viruses but smaller/less complex ● No protein coat, made of a single strand of circular RNA ● Damage caused when viroids compete for nucleotides - form

viroid bundles which disrupts internal structures

Prion ● Mad cow disease (CJD or BSE)

● Non-cellular proteins, NO nucleic acids ● Makes normal cells burst, but no immune response invoked

Virus ● HIV ● Influenza

● Non-cellular, composed of DNA/RNA with protein coat ● Damage caused when viruses infect host cells, multiply inside

and then destroy cell -> spreading

Bacteria ● Cholera ● H pylori

● Prokaryotic organisms, unicellular ● Classified according to shape (rod, spiral, spherical) ● Reproduction by binary fission

Protozoan ● Malaria ● Single-celled eukaryotes

Fungi ● Tinea ● Ringworm

● Macroscopic multicellular, however can be unicellular ● Heterotrophic eukaryotes ● Use fungal threads (hypha) to invade tissue

Parasitic worm

● Hydatid disease ● Multicellular eukaryotes, heterotrophic ● Macroscopic

Oomycetes ● Downy mildew ● Unicellular eukaryotes - protists ● Motile cells like flagella ● Reproduce like fungi (spores) ● Heterotrophic, cellulose cell wall

- investigating the transmission of a disease during an epidemic CASE STUDY: CHOLERA

● Caused by vibrio bacteria, direct life cycle (no vectors) ● Recent outbreak in Nigeria (September 2018) ● Transmission

○ Ingested through contaminated food or water bacteria infects bowel of human excreted in feces which can further spread disease

○ Developing countries at higher risk due to lack of infrastructure, insufficient education, poor sanitary conditions, and lack of drinking water

● Major symptoms ○ Cramps and diarrhea ○ Vomiting ○ Dehydration

● Treatment ○ Fluids and salts replaced (oral rehydration solution) ○ Antibiotics (in very early stages)

● Prevention ○ Vaccines and education ○ Avoidance of consuming contaminated water/food (purification)

● Control ○ Effective sewerage systems and proper infrastructure ○ Chlorination of water

- design and conduct a practical investigation relating to the microbial testing of water samples PRACTICAL INVESTIGATION

● Water testing kits – samples taken from a range of sources ● Using the test kit instructions, each sample was tested for coliform bacteria (sticks turned purple) ● Samples were also placed onto nutrient agar plates and incubated to ascertain the type and

number of bacteria present in the water. ● For safety, plates were sealed and never reopened autoclaved after results were obtained

SYDNEY WATER TREATMENT PROCESS

● Fine mesh screens used to remove debris ● Coagulant is added that makes small particles stick together and form 'flocs' (easier to filter out) ● Sediment is collected and pumped out from a sludge collector ● Filters made of tightly packed sand and coal are used to filter water again ● The pH of the water is carefully balanced ● Small amounts of chlorine are added to kill pathogens (primary disinfection) ● After water is transferred to reservoirs for distribution, more chlorine is added (secondary

disinfection)

- investigate modes of transmission of infectious diseases, including direct contact, indirect contact and vector transmission

● Endemic = the usual level of disease found within a population of a given area ● Epidemic = sudden increase of a particular disease among a population in a given area ● Pandemic = when a disease reaches above endemic levels on a global scale

METHODS OF TRANSMISSION

● Direct contact ○ Involves touching affected area of contagious person, passing pathogen to another

person ○ e.g. chicken pox or HIV (bodily fluids)

● Indirect contact ○ Involves inhaling pathogen, consuming contaminated food or water, touching

contaminated articles or transmission via a vector. ○ e.g. influenza (airborne), malaria (vectors), cholera (contamination)

1.2 investigate the work of Robert Koch and Louis Pasteur, to explain the causes and transmission of infectious diseases, including: - Koch’s postulates

● Robert Koch established the relationship between microbial pathogens and disease by experimenting on mice - criteria used to determine specific pathogens causing particular diseases

KOCH’S POSTULATES

1. Microorganisms must be present in tissue of the infected organism and not in a healthy organism 2. The microorganism must be able to be cultivated in isolation from the infected organism 3. When an uninfected organism is the inoculated with the culture, it should develop symptoms of

the disease 4. Samples from the second infected organism should be able to be isolated & found to be the same

as the micro-organisms from the first infected organism - Pasteur’s experiments on microbial contamination

● Determined that microbial pathogens are free living in the environment and are capable of infecting certain substrates = germ theory (replacing theory of spontaneous generation)

● Identified role of microbes in decay PASTEUR’S EXPERIMENT

● Prepared a broth and emptied equal amounts into TWO glass flasks - one with the "swan neck" and one kept straight (the bend allowed air to enter the flask while keeping pathogens out)

● Both flasks were heated to sterilise the broth and left to sit at room temperature for several weeks ● Observed that the open-necked flask had become cloudy, indicating contamination from germs

however the broth in the S-bend flask was unchanged

● Demonstrated that microbial germs are airborne and life cannot be generated from a sterilised medium

1.3 assess the causes and effects of diseases on agricultural production, including but not limited to: - plant diseases

● Travel within and between countries, bushwalking through affected areas and the import/export of agricultural products increases the speed at which pathogens are spread (human activity)

● Disease can easily wipe out entire species if there is a lack of genetic variation – e.g. plants grown through asexual methods making them genetically identical

PLANT DISEASES

● Example: potato blight (fungus) ● Potato turns brown and rots – will spread to tubers if left unchecked ● Leads to decrease in revenue of farmers (e.g. livelihoods threatened in 1800s Ireland - many

people died as a result of starvation) economic impact and global shortage of the crop - animal diseases

● Pathogens can also be transmitted to animals through infected birds, insects, water or food supplies

ANIMAL DISEASES

● Example: flystrike (parasite) ● Can affect a wide range of farm and pet animals e.g. rabbits, sheep, cattle and goats ● Blow flies lay eggs on the host and hatched maggots eat the flesh of the animal ● High economic impact on agricultural production: decreases productivity, increases time and

cost by treating or preventing flystrike and can cause a slow + painful death to the animals

1.4 compare the adaptations of different pathogens that facilitate their entry into and transmission between hosts ENTRY INTO HOST AND ADAPTATIONS

● Vectors ○ Outer layer of skin is impenetrable to most microorganisms. Pathogens that use biting

insects as vectors are able to penetrate the skin ○ e.g. malaria mosquito infected through blood = when feeding on another person the

pathogen is injected into their body ● Mucous membranes and chemical barriers

○ These barriers contain antibodies that bind to pathogens, preventing them from invading. ○ e.g. helicobacter pylori motile with special flagella that allow it to move through the

mucus lining of the stomach ○ Some bacteria are also able to change the pH of their environment to survive by

producing urease (neutralises acid) ● Antigenic variation

○ e.g. influenza constantly changing its DNA so the body does not recognise its markers and cannot fight it off with memory cells

● White blood cells ○ e.g. HIV aggressively attacks white blood cells so it cannot be fought off

● Biofilms and antibiotic resistance ○ e.g. staphylococcus bacteria naturally resistant to antibiotics, produce resistant

offspring and mutate to become completely resistant to antibiotic ○ Biofilms – bacteria clump together to protect themselves from antibiotics

● Change in host behaviour ○ e.g. toxoplasma gondii changes behaviour of rats, so they lose their natural fear of cats

= helps parasite to survive as cats eat infected rats and spread more of the pathogen TRANSMISSION BETWEEN HOSTS

IQ2: How do plants and animals respond to infection? 2.1 investigate the response of a named Australian plant to a named pathogen through investigation, for example: - fungal pathogens

● Plants can wilt from lack of water or nutrient uptakes, but also from certain fungal diseases that infect the soil and prevent materials from entering the plant

Feature Description

Common name of plant Bottle brush

Brief description of plant Bush related to myrtle family with colourful flowers, supplies nectar and food for a wide range of animals and insects

Fungal pathogen Myrtle rust

Symptoms of disease Deformed leaves, heavy defoliation, reduced fertility, dieback, stunted growth, death

Control of disease Removal of host material at infected properties, fungicide treatment, quarantine controls on infected properties to prevent movement of disease, general surveillance.

- viral pathogens

Feature Description

Common name of plant Native Wisteria

Brief description of plant Vigorous climbing plant with purple flowers whose branches twist around the stems of other plants, native to WA

Viral pathogen Hardenbergia mosaic virus

Symptoms of disease Leaf deformation, puckered or blistered leaves, bright yellow spots on leaves

Control of disease Quarantine controls on infected properties to prevent movement of disease, removal of host material at infected properties, general surveillance

PLANT IMMUNE RESPONSE

● Plants do not have an adaptive immune response – every plant has to respond to pathogens independently e.g. eucalypts contain toxic compounds

● They have an innate immune response and secrete defensive molecules e.g. insect moulting hormone ecdysone

● There are four main components of a plant's immune response: ○ Basal resistance

■ Activated when plant cells detect molecular patterns associated with pathogens – plants become impenetrable to protect from further infection

○ Gene-for-gene resistance ■ Plants are able to produce proteins through specific genes ■ These genes recognise corresponding virulence genes to pathogens, making the

plant resistant ○ Hypersensitive response

■ This response is activated by bacteria, fungi and nematodes when basal resistance is bypassed

■ Involves programmed cell death by host plant – restricts pathogen to infected cells only, limiting access to rest of plant

■ Plant cells will increase lignification of the cell walls to prevent further infection ○ Systemic acquired resistance

■ Induced when exposed to non-pathogenic microbes (non-specific mechanism) ■ Aids defensive cellular responses to chemicals/hormones

2.2 analyse responses of animals to pathogens by assessing the physical or chemical changes that occur in the cells and tissues of animals in the presence of pathogens INNATE IMMUNE RESPONSE

● Animals have a number of barriers that prevent pathogens from invading – these are non-specific, or 'innate'.

● Skin o Impenetrable barrier that prevents pathogens from invading

● Chemical barriers

o Oil and sweat produce lysozymes which keeps surfaces acidic, destroying the cell walls of pathogens

o Stomach acid and bile create an environment which most pathogens cannot survive in o Acidic, sterile urine flushes pathogens out of the urinary tract o Mucous membranes (viscous, slimy secretions) trap pathogens and foreign matter e.g.

respiratory tract, vagina ● Microflora

o Mutualistic relationship – healthy bacteria obtain nutrients in a stable environment and also protect against colonisation by other pathogens as they will have to compete for space and nutrients

● Peristalsis – contraction of muscles aids movement of mucus + cilia to flush out organisms IQ3: How does the human immune system respond to pathogens? 3.1 investigate and model the innate and adaptive immune systems in the human body DEFENSIVE MOLECULES - INNATE

Substance produced by infected cell

Why the substance is produced

Cytokines ● A group of signalling proteins including interferon, interleukin etc. that regulate the function of lymphocytes and defense cells.

Interferons (cytokine) ● Made by killer T cells, protects other cells from viral invasion as it activates antiviral genes

Chemokines (cytokine) ● ‘Flag’ proteins – help direct the movement of white blood cells to an injury site and induce other changes

Serotonin ● Made by platelets, causes vasoconstriction

Prostaglandins ● Made from cell membranes by nearly all cells and not stored. ● Has diverse actions, sometimes opposing e.g. fever, pain, vasodilation,

vasoconstriction and increased vascular permeability

Neutrophils ● Ingest foreign cells/materials (phagocyte) ● Release cytokines, disrupt pathogen membranes

Basophils + mast cells ● Release histamine (causing vasodilation) and heparin (anticoagulant) LYMPHATIC SYSTEM – ADAPTIVE

● Major structures = spleen and thymus o Spleen stores lymphocytes, destroys defective red blood cells and is a site of B cell activation o T lymphocytes mature in the thymus

● The lymphatic system returns fluid that seeps out of blood vessels back to the circulatory system.

o Transports lymphocytes to lymph nodes, stimulating adaptive immune response. o Lymph nodes act as filters which trap foreign particles, waste and pathogens – also contain

macrophages o Structure:

o 3.2 explain how the immune system responds after primary exposure to a pathogen ANTIGENS

● Antigens are proteins expressed on the surface of cells. ● There are two types of antigens: self-antigens (autoantigens) and non-self-antigens (foreign or

heteroantigens). o Foreign antigens are what trigger the (non-specific) inflammation response if they bypass

the first line of defense. ● Inflammation is the accumulation of fluid, plasma proteins and leukocytes which occurs when

tissue is damaged or infected. o Results in heat, pain, swelling, redness and loss of function.

STEPS IN INFLAMMATION (2nd LINE OF DEFENSE)

● When pathogens breach the first line of defense, injured cells release cytokines that attract neutrophils + other cells.

● Blood carries phagocytes (e.g. macrophages and neutrophils) to infected area that engulf foreign material

● Histamine causes vasodilation and fluid enters the surrounding tissues, carrying phagocytes and antibodies with it.

● Lymph nodes filter pus (dead cells). ● The inflammatory response continues until the pathogen is eliminated.

MHC MARKERS

● MHC markers (proteins expressed on cell surfaces) are used in the recognition of pathogens. ● MHC1 are present on every single nucleated cell in the body i.e. every cell except RBC.

o These markers present abnormal proteins when infected which signals killer T cells to destroy it.

● MHC2 markers are only found on antigen presenting cells i.e. macrophages and dendritic cells. o These cells engulf pathogens and present the antigen pieces on their markers which allows

helper T cells to bind and recognise the antigen. ADAPTIVE IMMUNITY (3rd LINE OF DEFENSE)

● Macrophage detects foreign particle with antigen attached to its surface and engulfs it by phagocytosis

● The antigen now displays on the surface of the macrophage, which is transported to the lymph nodes and presented to helper T cells

o Finds T cell whose receptor corresponds to that specific antigen, activating the T cell ↓

1. Humoral/antibody-mediated immunity: ● Helper T cells secrete cytokines which activates B cells and memory cells. ● B cells specific to that antigen are cloned and differentiate into plasma cells, which

then secrete antibodies/immunoglobulins specific to the antigen.

▪ These antibodies form an antibody-antigen complex and inactivate the pathogen through AGGLUTINATION (attaching), NEUTRALISATION (deactivating) and PRECIPITATION (clumping).

▪ antigen-antibody complex (variable Y regions = adaptability) 2. Cell-mediated immunity: ● Helper T cells secrete cytokines that activate memory T cells and cytotoxic T cells with

the particular antigen receptor on their surface. ● These move to the pathogen where it has been inactivated by antibodies and release

chemicals that destroy the cell and the pathogen within it. ● These chemicals attract more macrophages for phagocytosis (inflammatory response).

● Once infection is defeated, suppressor T cells release other chemicals to stop immune response. ● Memory B and T cells remain in the body for a more efficient immune response to future invasions

of the same pathogen. ↓

IQ4: How can the spread of infectious diseases be controlled? 4.1 investigate and analyse the wide range of interrelated factors involved in limiting local, regional and global spread of a named infectious disease FACTORS AFFECTING SPREAD OF INFECTIOUS DISEASE

● Human movement (transfer of pathogen locally, regionally or globally) ● Human behaviour (poor sanitation habits increase spread) ● Farming practices (facilitates transmission of disease e.g. Avian flu from chickens to humans ● Land clearing ● Environmental/geographic factors e.g. natural disasters ● Pathogen factors (virulence, adaptations, resistance)

DISEASE MONITORING AND CONTROL ● Because of the ease with which humans can travel, disease monitoring and control are carried

out at three levels: o Local

● Usually related to a neighbourhood, town or city ● Sanitation is a major factor in spread of disease, especially after natural disasters ● Poor communication networks and roads may limit access to medical treatment,

hospitals, medical info etc. ● Overcrowding increases host to host transmission

o Regional ● UN-5 region in world (Africa, Americas, Asia, Europe and Oceania) ● Geography influences transmission e.g. highly mobile populations have increased

exposure to infection than isolated ones o Global

● Increased movement of people globally because of travel/work/migration introduces difficulties in limiting spread of disease

● Internet increases up-to-date information about outbreaks of disease as they occur

EXAMPLE: LIMITING THE SPREAD OF MALARIA ● Local and regional measures

o Drainage programs to get rid of stagnant water cannot breed o Reduce contact with infected mosquitoes e.g. wear protective clothing, bug spray, use

mosquito nets in house o Screening for disease to prevent spread across regions

● Global measures o Vaccination programs o Global insecticides o Global communication about outbreaks of disease and information on how travellers

can protect themselves

4.2 investigate procedures that can be employed to prevent the spread of disease, including but not limited to: - hygiene practices ● Infectious diseases are transmitted between people through direct or indirect contact. ● Disease control can be aided with measures including improved hygiene practices, quarantine

and immunisation programs. o Factors that limit the effectiveness of these include poverty, high density

accommodation and access to quality medical services. HYGIENE ● Personal hygiene

o Thorough + frequent hand washing (kills and removes bacteria present on hands) o Protection during sex (prevents pathogens transferring through bodily fluids) o Cover mouth when sneezing or coughing (prevents pathogens transferring through

droplets) ● Government regulations

o Public services that help prevent the spread of disease ● e.g. disposing of sewage, household/medical waste, and providing CLEAN WATER

o Temporary infrastructure in the case of a natural disaster ● e.g. portable toilets, bottled water

● Safe food practices o Legislation is in place to avoid the spread of pathogens by food handling e.g. salmonella

● Hand washing and wearing gloves ● Cooking food thoroughly and storing food correctly

- quarantine

● Quarantine refers to all the measures taken to minimise the risk of infectious diseases caused by pathogens entering and establishing in Australia.

● Measures may include isolation or hospitalisation of infected people, closing schools or workplaces, and surveillance of people, animals & goods moving across borders o e.g. collection of passenger and cargo information at airports

● Australia has strict quarantine laws e.g. eradication of foot & mouth disease in farm animals o Illegal to bring meat/dairy products to Australia without a permit o Heavy penalties apply for illegal movement of these items which is de-incentivising,

protecting the population and economy - vaccination, including passive and active immunity public health campaigns VACCINATION ● Vaccination is a method of providing artificially acquired immunity without the need for a

person to have suffered the disease initially. ● Highly effective e.g. smallpox = WHO created global vaccination program and

eradicated the disease in 1980 ● Immunity is active or passive depending on the origin of the immune response. ● Problems with implementing vaccination include lack of monetary funding, poor health

resources and lack of public health education.

RECOMBINANT VACCINES ● A recombinant vaccine is a vaccine provided through recombinant DNA technology.

● Involves inserting the DNA encoding an antigen (such as bacterial surface protein) that stimulates an immune response into bacterial or mammalian cells, expressing the antigen in these cells and then purifying it from there.

● DNA cut with enzymes new DNA inserted recombinant DNA placed into something that replicates quickly e.g. yeast cell fermentation tank antigens are detached, extracted and put into vaccines

ACTIVE IMMUNITY ● Stimulates production of antibodies without need to suffer disease initially ● Person does not acquire disease but memory cells are manufactured and stored = future

immune response is faster and more effective if infection by same antigen occurs o e.g. tetanus or diphtheria injections

PASSIVE IMMUNITY ● Protection provided to an individual by the transfer of antibodies produced by another

organism ● Immediate but only short-term = does not activate immunological memory

o e.g. antibodies present in mother kangaroo milk provide protection to its joey, as their immune system develops after birth

HEALTH CAMPAIGNS ● Health authorities and government promote healthy behaviours through public health

campaigns. ● Information is distributed through media outlets/schools/mail etc.

o e.g. after the Giardia water crisis in Sydney - immediate campaign was launched: ● Educating the public about the pathogen ● Information about treatment of water supplies ● Bans on drinking water + instructions on boiling water ● Information about where/how to seek medical help if needed.

HERD IMMUNITY

● For immunisation to be successful, enough people need to be vaccinated (usually 90% and above) – this is called herd immunity

o The more people who are vaccinated, the less chance there is of an infectious agent spreading throughout a population because there are fewer potential carriers.

● Herd immunity is essential for the protection of those who cannot be vaccinated or have suppressed immune systems e.g. newborn babies or the elderly

- use of pesticides ● Pesticides are chemicals used to prevent the spread of infectious plant and animal diseases.

● May also help control insect vectors e.g. mosquitoes malaria ● May be used as sprays/baits, in irrigation water or as dips for farm animals (baths containing

insecticides) ● However, because of the overuse of pesticides, genetic resistance has developed among many

pests e.g. 90% of sheep parasites are now resistant to farming pesticides, meaning that new pesticides must constantly be developed

- genetic engineering ● Genetic engineering is used to modify the genetic structure of an organism using

biotechnology ● Helps prevent spread of disease by producing plants/animals resistant to common

pests/diseases, vectors with a diminished capacity to spread disease, and transgenic animals for harvesting biomedical products. o e.g. genetically engineered plant = BT cotton (transgenic cotton) BT bacteria has a gene

for making pesticides. o The gene from BT bacteria is removed using enzymes and inserted into the cotton plants

via a plant infecting bacteria, allowing the cotton plants to gain natural pesticide ● Less pesticide used has a good effect on ecosystems, however this creates less

variation in the crop.

4.3 investigate and assess the effectiveness of pharmaceuticals as treatment strategies for the control of infectious disease, for example: - antibiotics ● One way of controlling pathogens and their spread is to reduce the number of them in the

outside environment - e.g. many bacteria are pathogens and can be treated with antibiotics ● Disinfectants are used to kill pathogens on surfaces such as door handles and hospital

equipment e.g. chlorine and hydrogen peroxide. ● Antiseptics, such as ethanol, iodine and some detergents are used to kill pathogens on the

body reduces chances that infection will occur ● Successful antibiotics kill bacteria without damaging the cells of the organism being treated. ● Should target biochemical pathways and molecules specific to the microbe e.g. bacterial cell

walls makes cell burst ● Antibiotics that slow bacterial growth = bacteriostatic, those that kill bacteria = bactericidal ● Narrow spectrum antibiotics only act on specific bacteria and broad-spectrum act on a wide

variety (when identity of bacteria is unknown) ● Disadvantages include:

o They kill good bacteria (flora) residing in the body o Antibiotic resistance can develop e.g. MRSA (golden staph) and methicillins

● Can be acquired through mutation, intrinsic resistance or DNA transfer - antivirals ● Viruses are non-cellular pathogens that must be inside living cells to replicate ● Antiviral drugs fight infection by either inhibiting a virus' ability to reproduce, or strengthening

the body's immune response to the infection – includes: ● Preventing virus from entering cell by binding to receptors that allow virus to enter ● Inhibiting enzymes that catalyse reproduction of virus genome ● Blocking transcription and translation of viral proteins ● Preventing viruses from leaving cell and so preventing infection of other cells

● Good targets for antiviral drugs are capsid proteins and envelope proteins ● Narrower range of organisms – viruses treated by antivirals include influenza, HIV, herpes,

hepatitis B. ● However viruses can develop resistance like antibiotics – implications include:

● Death from treatment failure ● Economic impacts e.g. costs of care/drugs

4.4 investigate and evaluate environmental management and quarantine methods used to control an epidemic or pandemic

● Preventing the transmission of pathogens in a serious epidemic requires the use of procedures and protocols called controls o These include environmental and quarantine measures.

Method Description

Standard precautions Hand hygiene, use of PPE e.g. gloves, eyewear, gowns, safe handling and disposal of sharps, routine cleaning of surfaces and equipment, and using aseptic techniques in in handling body fluids to prevent/control infection and reduce the possibility of an epidemic.

Water supply

The transmission of many pathogens occurs due to the use of contaminated water e.g. diseases such as cholera, typhoid, and dysentery. Clean water supplies are essential to prevent and control infectious diseases and a potential epidemic.

Sanitation facilities The transmission of many pathogens occurs when water, food, or utensils are contaminated with faeces e.g. hepatitis A and salmonella. The treatment and disposal of sewage dramatically reduces the risk of disease epidemics.

Food supply

Poor quality control of food supplies, food preparation, cooking procedures and disposal of wastes can lead to the transmission of an infectious disease and cause an epidemic e.g. mad cow disease with infected beef

Reducing transmission

Environmental controls can reduce disease transmission e.g. interrupting the life cycle of a vector such as removing stagnant water where mosquitoes breed.

Contact tracing

When an outbreak occurs all infected people and the people they have contacted need to be traced and tested for the disease. If necessary these people may need to be quarantined for the required incubation period.

Quarantine Keeping infected individuals isolated and in quarantine is one of the most important controls in reducing further transmission of the disease.

Public health infrastructure

Quality public health infrastructure provides the means to diagnose, treat and care for infected individuals. Isolation in proper medical facilities provides the greatest possibility of survival for an individual and restricts further transmission.

4.5 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 INCIDENCE ● The incidence of disease is the rate of occurrence of new cases, which indicates the risk of

people contracting the disease. Incidence is expressed as a fraction of a population within a period of time. o E.g. during the years 2000 to 2011 there were 990 new cases of measles in Australia.

Therefore, the annual rate was 0.4 per 100 000 population. PREVALENCE ● The prevalence of disease measures the proportion of cases in the population and a given

time, which indicates the spread of disease. o E.g. on 1 January 2017, out of 10,000 people in Town A, 40 have measles. o Population ÷ cases = 0.4%.

MOBILITY

● The increase of globalisation and as air travel facilitating fast movement of people across geographic areas increases the risk of exposure to infectious disease

o e.g. prevalence of Dengue in Asia increased following WW2, when ecological/demographic changes led to the transport of Aedes mosquitoes and an increase in the number of hosts ● Post-war, the rapid urbanisation of SE Asia meant that infrastructure such as

sewage systems were inadequate and left population susceptible to infectious disease

4.6 evaluate historical, culturally diverse and current strategies to predict and control the spread of disease JOHN SNOW – CONTRIBUTION TO DISEASE CONTROL (CHOLERA)

MONITORING, CONTROLLING AND ERADICATING RABIES ● Sri Lanka and Thailand have recorded a sharp decrease in the no. of rabies deaths after mass

dog vaccination and improved access to human pre- and post-exposure vaccines o Also helps prevent the spread of disease to other countries by mobility e.g. rabies does

not exist in Aus despite travel and trade links to SE Asia

4.7 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 PATENTS/INTELLECTUAL PROPERTY

● Indigenous Australians have made and passed down observations and inferences about how Australian plants could be used to help treat diseases for centuries.

● Many modern products have been developed using traditional knowledge of bush medicine o e.g. the Bundjalung Aboriginal people from NSW used crushes tea-tree leaves to

treat wounds and sore throats - since 1920s tea tree oil is used in many products and is shown to have antiseptic properties

● Protecting Indigenous intellectual property is critically important to protect their culture from commercialisation - therefore legalisation must be established in order to recognise them for their discoveries for fairness and equity.

EXAMPLES OF BUSH MEDICINE

SMOKE BUSH