Disease challenges and strategies

Question 1

Emerging Pathogens

Answer 1

A previously unknown or new pathogen that has spread to new populations/locations
Eg: influenza, avian influenza and COVID-19

Question 2

Re-emerging Pathogens

Answer 2

Pathogens that have caused disease in the past and are now reappearing into a population without immunity and increases to an epidemic proportion
Eg: measles, tuberculosis, malaria, gonorrhoea

Question 3

Sporadic

Answer 3

If they are only seen infrequently and in small numbers of people
Eg. the occasional cases of rabies

Question 4

Endemic

Answer 4

If they are consistently found in certain regions
Eg. malaria which is endemic to tropical regions

Question 5

Epidemic

Answer 5

Rapid spread of the disease across a number of countries and a large number of people are affected
Eg. the Ebola outbreak in 2018 which spread across the Democratic Republic of Congo and Uganda

Question 6

Pandemic

Answer 6

If pathogens become worldwide threats to health, huge financial burden, high mortality rate
Eg. COVID-19 pandemic starting in late 2019

Question 7

European arrival on Aboriginal and Torres Strait Islander peoples

Answer 7

British colonisation in Australia led to the dramatic decline in populations of Australian Aboriginal peoples and Torres Strait Islander peoples due to introduction of new diseases that the population had no prior exposure to.
This included: smallpox, chickenpox syphilis, tuberculosis, influenza and measles.
These diseases devastated Aboriginal and Torres Strait Islander peoples resulting in significant fatalities.
The arrival of Europeans had an almost immediate impact.
- Land clearing for crops
- Fencing of livestock
- Water management
- Forestry for wood
- Introduction of weed species
- Hunting of native wildlife.
→ This resulted in many Aboriginal people becoming malnourished or dying of starvation.
→ After being dispossessed of their land, Aboriginal people started living much closer together in communities and this only exacerbated the spread of diseases

Question 8

Physical methods

Answer 8

identifying pathogens based on shape and size
- X-ray crystallography- determines the structure of many viruses
- Electron microscopy - helps distinguish various kinds of viruses

Question 9

Immunological methods

Answer 9

Detect specific viral antigens or antibodies
- Sandwich ELIZA
Antibody put at bottom of well, human serum added (with antigen), antibody with enzyme added to see if the person has the pathogen through a colour change

Question 10

Genotypic and molecular methods

Answer 10

Methods of identifying bacteria by examining its genetic material

Question 11

Phenotypically

Answer 11

Grow things on agar plate and add stains
Gram staining

Question 12

Sterilisation

Answer 12

The removal or killing of the microbes from surfaces. Done by heat (methods as autoclaving) → Very effective method and relies on pressurised steam at a high temperature.

Question 13

Chemical agents

Answer 13

Antiseptics and disinfectants
Disinfectants inhibit or kill pathogenic organisms on non-living surfaces, such as taps and door handles.
Antiseptics are used for inhibiting the growth of pathogens on living surfaces such as the skin.

Question 14

Antibiotics

Answer 14

Class of antimicrobial drug used in the treatment and prevention of bacterial infections

Question 15

Antivirals

Answer 15

A type of medication that is used specifically for treating viral infections.

Question 16

Social strategies to control spread

Answer 16

Restrict movement of people
- Lockdown, work from home, quarantine for returned travellers, quarantine for conant of infected individual, travel restriction, limiting visitors at home
Prevent spread from person to person
- Social distancing, masks
Reduce chances of infection
- Public education about personal hygiene, vaccination programs
Manage illness when injected
- GPs, hospital care
How authorities can assess risk
- Testing, contact tracing, wastewater testing

Question 17

Modes of transmission

Answer 17

• Direct transmission- such as by person to person contact→ kissing, sexual contact (eg. chickenpox, chlamydia)
• Indirect transmission:
  By airborne droplets or particles (sneeze or cough)
  By contact with contaminated objects (medical instruments)
  By ingestion of contaminated food or water
  By biological vehicles (contaminated blood or faeces)
  By vectors (ticks, mites, fleas or mosquitoes)

Question 18

R0

Answer 18

The R0 value (the basic reproduction value) is the average number of people an individual with a disease will infect.
D = duration of infection, B = how many individuals are infected by an infectious person per day
R0 = D x B

Question 19

Vaccination programs

Answer 19

Aim of vaccination programs is to reduce the impact of vaccine-preventable infectious diseases through achieving high rates of immunisation in the community.

Question 20

Herd immunity

Answer 20

Is the indirect protection of unvaccinated members of the population due to the vaccination of the majority of the population

Question 21

Immunotherapy

Answer 21

Immunotherapy is a type of treatment that alters the immune response in an individual to combat diseases such as cancer and autoimmune diseases. One treatment used is monoclonal antibodies

Question 22

Monoclonal antibodies

Answer 22

Class of drugs that are specifically designed antibodies used in the treatment of some diseases: cancer and autoimmune disease (cloned antibodies)
They are artificially produced antibodies that bind to one specific type of antigen
Produced in the laboratory by stimulating the production of B lymphocytes in mice injected with a specific type of antigen

Question 23

How to make Monoclonal antibodies

Answer 23

1. A lab mouse is injected with antigen X which activates the production of B cells, producing antibodies against antigen X.
2. Stimulate artificial active immunity in mouse - plasma cells are produced against antigen X
3. These cells are fused with a tumour inducing cell and become a hybridoma cell (continue cloning and creating the antigen).
   *conjugated add chemotherapy drug to monoclonal antibody - will help deliver chemotherapy

Question 24

Monoclonal antibodies for autoimmune diseases

Answer 24

• Monoclonal antibodies can be designed to act against specific cells of the immune system which cause autoimmune disease.
• There are currently no reliable and safe strategies to cure autoimmune diseases. Severe cases require cytotoxic drugs, which frequently cause serious side effects.

Question 25

Autoimmune disease

Answer 25

When the ‘self’ recognition in the immune system fails, and a person’s immune system attacks and destroys their own body cells, tissues or organs. The body produces autoantibodies (antibodies that attack the body’s own cells)

Question 26

Monoclonal antibodies for cancer

Answer 26

• Researchers can design antibodies that target particular antigens on cancer cells
• Monoclonal antibodies are often used in combination with chemotherapy and/or radiotherapy.
  The four main modes of action of MAbs are to:
• stop the growth of new blood vessels - prevent growth of malignant tumour by preventing the tumour from getting oxygen + nutrients
• signal immune cells to attack the tumour- by binding to antigens on cancer cells, acting as markers
• block growth factors
• deliver anticancer or radioisotopes to cancer cells- conjugated MABs