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Biology U3/4 > Chapter 6: Disease Challenges and Strategies > Flashcards

Chapter 6: Disease Challenges and Strategies Flashcards

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
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2
Q

Provide examples of new and re-emerging pathogens

A
  • New pathogens → COVID-19 and HIV
  • Re-emerging pathogens → Ebola and cholera
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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)
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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
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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)
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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
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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
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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
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9
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Explain and list phenotypic methods used to identify pathogens

A
  • Phenotypic methods involve identifying observable traits or features in bacteria
  • Gram staining
  • Observing growth
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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)
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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
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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
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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.

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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
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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
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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
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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
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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
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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
Q

State the advantages and disadvantages of herd immunity

A
  • 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
Q

List reasons that prevent some people from being vaccinated

A
  • 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
Q

Explain how herd immunity protects the unvaccinated

A
  • 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
Q

State reasons for why a newborn child may be less susceptible to an infectious disease

A
  • 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
Q

Discuss the ethics of refusing to be vaccinated

A
  • 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
Q

Define immunotherapy

A
  • Immunotherapy is a disease treatment that involves either stimulating or repressing the immune response
  • E.g. monoclonal antibodies
31
Q

Explain monoclonal antibodies

A
  • 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
Q

Explain how monoclonal antibodies are produced

A
  • 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

NOTE: Plasma cells are short lived while myeloma (tumour) cells are immortal.

33
Q

List the advantages and disadvantages of monoclonal antibodies

A
  • 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
Q

Describe ways in which monoclonal antibodies can act to treat cancer

A
  • 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

NOTE: They can be used in the treatment of rheumatoid arthritis as they play a role in reducing inflammation.

35
Q

Explain and provide examples of autoimmune diseases

A
  • 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
Q

Explain how monoclonal antibodies can be used to treat autoimmune diseases

A
  • 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
Q

Define cancer

A
  • Cancer is a disease in which cells divide uncontrollably, forming an abnormal mass of cells called a tumour
38
Q

Explain the difference between immunotherapy and chemotherapy when treating cancer

A
  • 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

NOTE: Chemotherapy is NOT an example of immunotherapy. They are two separate treatments.

39
Q

Outline strategies that may used to increase vaccination rates in Indigenous Australians

A
  • 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
Q

Define virulence

A
  • Virulence refers to the severity of disease caused by a pathogen
41
Q

Explain how MAbs block signals for cell division

A
  • 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)

NOTE: Healthy tissues receive signals from growth factors for normal cell replacement.

42
Q

Explain how MAbs deliver anticancer or radioisotopes to cancer cells

A
  • 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
Q

Explain how MAbs signal immune cells to attack cancer cells

A
  • 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
Q

Explain how MAbs can stop the growth of new blood vessels to cancers

A
  • 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
Q

State how sterile conditions can be achieved in a hospital

A
  • Flaming, steaming, boiling or autoclaving medical equipment
  • Using antibacterial handwash
  • Using disposable gloves

Biology U3/4 (12 decks)

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