Chapter 6: Disease Challenges and Strategies Flashcards
(45 cards)
1
Q
x
Define new and re-emerging disease
A
- Emerging diseases are caused by newly identified or previously unknown pathogens
- Re-emerging diseases involve the reappearance of a pathogen after being absent in a population for a significant period of time
2
Q
Provide examples of new and re-emerging pathogens
A
- New pathogens → COVID-19 and HIV
- Re-emerging pathogens → Ebola and cholera
3
Q
State the difference between an epidemic and a pandemic
A
- An epidemic is a local outbreak of infectious disease
- A pandemic is a widespread outbreak of infectious disease (present in at least 2 World Health Organisation regions)
4
Q
Explain why living in a globally connected world increases the likelihood of pandemics
A
- Greater mobility (e.g. air travel) in the globally connected world allows pathogens to be exported from one country to another through infected passengers
5
Q
Explain the impact of European arrival on Indigenous populations
A
- Many Aboriginal Australians died due to infectious diseases that were introduced by Europeans
- Australia is geographically isolated
- Prior to European arrival there was little interaction between Europeans and Indigenous Australians
- Western diseases were unknown, so Indigenous populations had no immunity against them (high susceptibility and rapid spread of new infectious disease)
6
Q
Explain and list physical methods used to identify pathogens
A
- Physical methods involve identifying pathogens based on size and shape
- X-ray crystallography → determines structure of viruses
- Electron microscopy → obtains images that allow viruses to be distinguished from one another
7
Q
Explain and list immunological methods used to identify pathogens
A
- Immunological methods involve the diagnosis of pathogens based on the presence of specific antigens or antibodies
- ELISA (enzyme linked immunosorbent assay) → allows for the diagnosis of disease by detecting specific antigens or antibodies
- MAB (monoclonal antibodies) → designed to have a specific antigen binding site
- Immunofluorescence → uses an antibody with a fluorescent marker to bind to and detect specific antigens or antibodies in serum
8
Q
Explain and list molecular methods used to identify pathogens
A
- Molecular methods involve identifying a pathogen by examing genetic material using DNA or RNA
- PCR (polymerase chain reaction)
- Gel electrophoresis
- Sequencing
9
Q
Explain and list phenotypic methods used to identify pathogens
A
- Phenotypic methods involve identifying observable traits or features in bacteria
- Gram staining
- Observing growth
10
Q
Explain the immunological process of ELISA
A
- Wells on a tray are coated with an antigen specific to the disease being tested
- Antibodies specific to a particular antigen is added to each well
- Antibodies bind to the antigen in the wells
- The wells are then washed to remove any unbound antibodies
- The substrate for the enzyme is added, leading to a colour change if an antigen-antibody complex has formed (this indicates a positive test)
11
Q
Describe how pathogens can be transmitted between individuals
A
-
Direct transmission involving direct person-to-person contact
- E.g. kissing or sexual contact
-
Indirect transmission that does not involve person-to-person contact
- E.g. inhaling airborne particles such as uncovered sneezes, contact with contaminated objects or ingestion of contaminated food
-
Vectors that are a form of indirect transmission
- E.g. organisms such as fleas and mosquitos that carry pathogens and spread them to other organisms via bites or droppings on food
12
Q
Explain how a disease that starts in a small population can spread around the world within a few weeks or months
A
- Asymptomatic people can spread the disease before they start showing symptoms
- People are very mobile and are able to travel large distances quickly by car, train and plane
- Some animals such as birds (for avian flu) can fly long distances, carrying pathogens between countries
- High population density increases the likelihood for diseases to spread
- Some countries may have poor sanitation/quarantine conditions and hence are unable to effectively isolate infected individuals from the community
13
Q
Describe control measures to prevent or limit the spread of infectious disease (PVMSI)
A
- Prevention strategies such as hand washing, using clean water and having safe sex, etc.
- Vaccination to reduce the number of hosts
- Medication to reduce transmission
- Surveillance which involves monitoring outbreaks
- Improving infection control standards such as sterilization of surfaces, masks, quarantine, etc.
TIP: Preventing Viruses Means Staying Informed.
14
Q
Explain why identifying the host or reservoir is important in controlling the spread of disease
A
- Transmission occurs when a pathogen leaves its reservoir (habitat) or host (organism that can be infected) and enters a susceptible host
- By identifying these areas, preventative measures can be placed to control the spread
15
Q
Define and describe ways that antibiotics work
A
- Antibiotics are substances, that in low concentrations, kill or inhibit the growth of bacteria
- Penicillin inhibits cell wall synthesis in bacteria
- Sulfanilamide competitively inhibits enzyme activity in bacteria
- Rifampin and quinolones inhibit nucleic acid synthesis
16
Q
Describe ways that antivirals work
A
- Antivirals are substances that are used to treat viral infections (actively replicating viruses)
- Prevent the entry of viruses
- Prevent replication of the viral genome
- Prevent synthesis of specific viral proteins
17
Q
Describe why antibiotics are not effective in treating viral infection
A
- Because they inhibit the growth of/kill bacteria rather than viruses
- They inhibit cell wall synthesis, bacterial reproduction or protein synthesis
- Viruses are non cellular and are therefore unnaffected by antibiotics
18
Q
Define and state what is in a vaccine
A
- A vaccine is a substance containing live attenuated antigens that elicit an immune response
- A vaccine contains live attenuated pathogens that cannot cause disease
19
Q
Suggest reasons for why vaccination rates may be lower in a region
A
- Less education about the importance of vaccines
- Less accessibility to vaccines due to cost
- Lack of medical staff who can administer vaccines
- Lack of mandatory vaccination laws
20
Q
Give examples of 3 vaccines that are on the Australian vaccination schedule and the age at which they are given
A
- Hepatitis B → preferably within 24 hours of birth
- Meningococcal → 12 months
- Human papillomavirus (HPV) → 12-13 years
21
Q
Explain how vaccines provide long-term immunity
A
- Vaccines initiate an immune response that results in the production of memory cells
- These memory cells remain in the lymphatic system and can initiate a stronger and more rapid immune response should reinfection with the same specific antigen occur
22
Q
Explain why booster shots are needed for some vaccines
A
- Booster shots help retain a memory of the pathogen and maintain the number of memory B cells and antibodies
- Inactivated vaccines (compared to live attenuated vaccines) produce a weaker immune response where immunity lasts for a shorter period of time
- As a result, they need to be administered more than once in order to maintain immunity against a disease
23
Q
Explain why diseases such as influenza need new vaccines each year
A
- Some diseases can mutate into new strains
- Antibodies produced by previous vaccines will fail to work against the new strain as they cannot bind to the mutated antigens
- Therefore, vaccines must be developed in order to adapt to mutatations as humans would have no immunity to the new strains
24
Q
Define herd immunity
A
- Herd immunity involves the indirect protection from infection of unvaccinated people by being surrounded by people who are vaccinated
- 95% should be vaccinated for herd immunity to occur
- Protection is created by the presence of immune individuals
- Protection is received by unvaccinated individuals
25
State the advantages and disadvantages of herd immunity
- **Advantages**
- Protects vulnerable individuals who cannot be vaccinated
- Reduces the spread of diseases
- **Disadvantages**
- Relies on very high vaccination rates (difficult for poor countries to achieve)
- Potential for outbreaks if herd immunity is not maintained or if immunity wanes over time
26
List reasons that prevent some people from being vaccinated
- **Weak immune systems** (immunocompromised)
- Being **too young or too old** for specific vaccinations
- **Lack of access to hospitals or medical staff** that can administer vaccinews
27
Explain how herd immunity protects the unvaccinated
- Unlikely that vaccinated individuals become infected and pass it on to unvaccinated people
- If the large majority of a population is immune, the **disease will not get the chance to spread** which reduces the risk for those who cannot be vaccinated
28
State reasons for why a newborn child may be less susceptible to an infectious disease
- They are **protected by their mother’s antibodies** passed down through the placenta or through breast milk (passive natural immunity)
- **Less exposure** to the virus due to **limited human contact**
29
Discuss the ethics of refusing to be vaccinated
- Respecting an individual's autonomy (by honouring their feelings, needs and decisions) is a fundamental ethical principle. People have the right to make decisions about their own bodies, including whether or not they wish to be vaccinated.
- However, respecting the rights and well-being of vulnerable populations is equally important. Individuals who cannot get vaccinated due to age or immunodeficiency disorders rely on herd immunity to receive protection against infection. Therefore, **refusing vaccination without a valid medical reason may jeopardize the health of these individuals and could be seen as a lack of respect for their well-being**.
30
Define immunotherapy
- Immunotherapy is a **disease treatment that involves either stimulating or repressing the immune response**
- E.g. monoclonal antibodies
31
Explain monoclonal antibodies
- Monoclonal antibodies are **artificially produced antibodies that bind to one specific type of antigen**
- They are produced in the laboratory by stimulating the production of B lymphocytes in mice upon injection of a specific type of antigen
32
Explain how monoclonal antibodies are produced
- A **mouse is injected with an antigen**
- This stimulates an active immune response involving the **production of the mouse's B cells**, which **produce antibodies** against the antigen
- The **spleen of the mouse is removed**, placed in a culture medium and its cells are separated
- B cells fuse with tumour cells to form **hybridomas**
- **Hybridoma cells divide** repeatedly and identical copies of each individual hybridoma cell are produced
- **Clones are screened** to identify cells that produce the required antibodies against the antigen
- The **antibodies can then be collected and purified**
## Footnote
NOTE: Plasma cells are short lived while myeloma (tumour) cells are immortal.
33
List the advantages and disadvantages of monoclonal antibodies
- **Advantages**
- Highly specific (only binds to specific antigens and does not affect healthy cells)
- Can be standardised world-wide
- Consistent quality
- **Disadvantages**
- High cost of production
- Limited availability
- Potential side effects
34
Describe ways in which monoclonal antibodies can act to treat cancer
- Attach to the cancer cell to stimulate its destruction
- Block the growth of blood vessels to a tumour
- Block signals for cell reproduction
- Take chemotherapy drugs directly to the cancer
- Make it easier for immune cells to detect cancer cells
## Footnote
NOTE: They can be used in the treatment of rheumatoid arthritis as they play a role in reducing inflammation.
35
Explain and provide examples of autoimmune diseases
- An autoimmune disease is when the **body's immune system attacks its own cells**
- They **occur when autoantibodies are produced or when T/B cells are inappropriately activated**
- Multiple sclerosis → immune system attacks the myelin sheath that protects nerves
- Type 1 diabetes → immune system mistakenly attacks and destroys pancreatic tissues and cells
36
Explain how monoclonal antibodies can be used to treat autoimmune diseases
- **Bind to cytokines** to prevent B-cell signalling and activation
- **Bind to T cells**, stopping their movement to the brain/spinal cord and attacking the myelin sheath
- **Bind to IgE** to prevent allergies
37
Define cancer
- Cancer is a disease in which **cells divide uncontrollably**, forming an abnormal mass of cells called a tumour
38
Explain the difference between immunotherapy and chemotherapy when treating cancer
- **Chemotherapy acts directly on tumour cells** → including healthy cells which can cause side effects such as hairloss and fatigue
- **Immunotherapy acts on the patient's immune system** → can have fewer side effects but may not be effective for all cancer patients
- Immunotherapy offers the potential for long-term control against cancer by retaining a memory
- Chemotherapy generally works quicker compared to immunotherapy
## Footnote
NOTE: Chemotherapy is NOT an example of immunotherapy. They are two separate treatments.
39
Outline strategies that may used to increase vaccination rates in Indigenous Australians
- Community elders could be educated to provide a trusted source of information to the Indigenous community
- Vaccination programs can be directly held in Indigenous communities
- Media campaigns, including Indigenous Australians, can be created to promote vaccination
40
Define virulence
- Virulence refers to the **severity of disease caused by a pathogen**
41
Explain how MAbs block signals for cell division
- Growth factors bind to receptors on cancer cells, signalling them to divide
- In cancerous cells, the receptor is over-expressed, resulting in uncontrollable division
- MAbs can bind to these receptors, blocking them from receiving signals from growth factors (slowing/preventing the growth of the cancer)
## Footnote
NOTE: Healthy tissues receive signals from growth factors for normal cell replacement.
42
Explain how MAbs deliver anticancer or radioisotopes to cancer cells
- MAbs can be joined with a radioisotope particle, delivering it to cancer cells
- The antibody links to its target antigen on the cell
- This causes the radioisotope to emit radiation, destroying the cancer cell
43
Explain how MAbs signal immune cells to attack cancer cells
- MAbs can bind to antigens on cancer cells, acting as markers that make them more visible to the immune system
- This attracts immune cells to attack the cancer cells
44
Explain how MAbs can stop the growth of new blood vessels to cancers
- Cancer cells require oxygen and nutrients to grow
- They release growth factors (hormones) that signal the growth of blood vessels (provide oxygen and nutrients)
- MAbs can bind to growth factors, preventing the growth of new vessels
45
State how sterile conditions can be achieved in a hospital
- Flaming, steaming, boiling or autoclaving medical equipment
- Using antibacterial handwash
- Using disposable gloves
