13 Communicable diseases Flashcards

1
Q

what is vaccination?

A

deliberate exposure of an individual to antigens from a foreign source in order to provoke an immune response and provide immunity

(i.e. artificial active immunity)

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2
Q

why does a vaccination work to prevent development of symptoms from infection?

A

generates a primary immune response and stimulates memory cells

∴ in future faster secondary response will occur following infection

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3
Q

what is a live attenuated vaccine? what is a strength and

a limitation of it?

A

modified strains of bacteria/viruses that can multiply BUT are not pathogenic

+ strongest response and ∴ long-lasting immunity
- cannot be given to people with compromised immune systems

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4
Q

what is a killed-inactivated vaccine? what is a strength and a limitation of it?

A

bacteria/virus is killed with chemical treatment, but antigens remain intact, provoking an immune response

+ more stable than live-attenuated, and does not require refrigeration
- provokes weaker immune response ∴ booster(s) needed

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5
Q

what is a toxoid vaccine? what is a strength and a limitation of it?

A

toxoids are extracted and treated with formaldehyde to prevent symptoms –> triggers immune response and production of antitoxins

+ safe when toxins are reason for virulence
- does not give a strong immune response

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6
Q

what is a subunit vaccine? what is a strength of it?

A

only specific antigens extracted and used

+ can construct vaccines for several strains

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7
Q

what is an artificial antigen recombinant vector? what is a strength of it?

A

genes coding for the antigens of the pathogen are transferred through genetic engineering to harmless microorganisms

+ provides immunity to agents that can’t easily be attenuated without destroying antigen activity

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8
Q

what is the aim of a vaccination programme?

A

to protect the population from a wide range of disease

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9
Q

why are boosters used?

A

to increase the number of memory cells

increases speed of secondary immune response to destroy pathogen before it can cause disease

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10
Q

how are vaccines used to prevent epidemics?

A

reducing chance of transmission

by increasing herd immunity

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11
Q

what is ring vaccination?

A

a vaccination ring around the geographical centre of an epidemic to prevent its spread

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12
Q

give three advantages of vaccination programmes

A

few/no side effects

economically viable for the whole population

easy to produce, transfer and store

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13
Q

how can the mutation of a pathogen prevent a vaccine being effective?

A

change in genetic material causes change in antigens/glycoproteins

∴ previous vaccine no longer has complementary antibody ∴ cannot bind to antigen

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14
Q

how can surface antigen variation prevent a vaccine being effective?

A

difficult to target all different antigens (especially if high mutation rate)

different strains in different geographical locations

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15
Q

give three biological problems in implementing vaccines

A

live-attenuated pathogen could mutate and become virulent

storage/transport/distribution can be expensive if refrigeration is required

low nutritional state of target population may have weakened their immune systems

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16
Q

what is protein energy malnutrition?

A

insufficient protein consumption

∴ can’t make antibodies/memory cells due to insufficient amino acids

17
Q

give an example of ethical issues surrounding vaccination testing

A

religious/cultural beliefs

lack of trust in government/health service

animal testing

side effects

ethics of pharmaceutical companies

consent vs. protection rights

18
Q

what vaccine is used against HPV?

A

subunit - contains proteins but no viral DNA ∴ no risk of infection

19
Q

what is an antibiotic?

A

a chemical that kills or slows down the growth of bacteria

20
Q

what type of cells do antibiotics have no effect on?

A

eukaryotic cells

viral particles

21
Q

what are bacteriocidal antibiotics? how do they work?

A

kill bacteria

by disrupting the cell wall or protein synthesis

22
Q

how does penicillin kill bacteria?

A

prevents synthesis of peptidoglycan cell wall ∴ no bacterium cell wall ∴ cell bursts

23
Q

how does polymyxin B kill bacteria?

A

damages plasma membrane by targeting phospholipids not found in eukaryotes –> contents of the cell leak

24
Q

what are bacteriostatic antibiotics? how do they work?

A

prevent growth/reproduction of bacteria

e.g. tetracycline prevents tRNA from binding to the ribosomes ∴ protein synthesis cannot take place

25
Q

what are sulphonamides? how do they work?

A

competitive inhibitors of bacteria membranes

inhibition of enzymes that assist in the synthesis of folic acid ∴ DNA (purines) can’t be synthesised

26
Q

how does erythromycin work?

A

blocks sites on ribosomes preventing protein synthesis

∴ polypeptide chain can’t be elongated

27
Q

what is the difference between broad and narrow spectrum antibiotics?

A

broad: work well against a wide range of bacteria
narrow: only effective against certain types of infection

28
Q

how does antibiotic resistance come about?

A

spontaneous mutation in the bacterium

∴ more tolerant to antibiotic

∴ more likely to survive

29
Q

how is antibiotic resistance prevented?

A

preventing misuse of antibiotics

completing the course

preventing damage to useful bacteria in the gut and microbiome

30
Q

outline some ways of reducing the spread of resistance

A

completing the course

reducing overuse

increased presence in animal feed

reducing contamination of door handles/equipment

aseptic techniques

isolating infectious patients

reducing use of anti-bacterial handwash