C13 - Communicable Diseases

Question 1

What are the different examples of vaccine?

Answer 1

Live-attenuated vaccines

Killed inactivated vaccines

Toxoids

Subunit vaccines (isolated extracted vaccines) and conjugate vaccines

Artificial antigens or recombinant vector vaccines.

Question 2

What are toxoids?

Answer 2

Vaccines produced where toxins are extracted and treated with formaldehyde to prevent the toxin causing disease symptoms.
This causes the immune system to produce antitoxins.

Question 3

What are subunit vaccines (isolated extracted vaccines) and conjugate vaccines?

Answer 3

Specific antigens (generally polysaccharides) which promote the immune response are extracted and used in the vaccine. 
In conjugate vaccines, the antigen is joined to a protein.

Question 4

How are artificial antigens or recombinant vector vaccines produced?

Answer 4

Using genetic engineering, genes for the antigens of specific pathogens are transferred into harmless microorganisms.
This creates harmless live vaccines.

Question 5

What is the point of booster vaccine?

Answer 5

To increase the number of memory cells and ensure the secondary repose is rapid enough to destroy the pathogen.

Question 6

What’s a ring vaccination?

Answer 6

When all individuals in the immediate area and those who have been in contact with those infected are vaccinated.

Question 7

Why is it difficult to develop vaccines against viruses?

Answer 7

The mutation rate of pathogens, leading to changes in the antigens and protein coats of the virus.
Changes means the antibodies already present in the body wouldn’t be able to bind to the antigens.

The variability of antigens and mutation rate makes it hard to produce vaccines quickly.

Question 8

What are the issues with implementing a new vaccine?

Answer 8

Future mutations in the attenuated virus may result in the pathogen becoming virulent again and show symptoms.

Storage, distribution and transportation of vaccines is also difficult.

Deficiencies in the receiving population’s nutrition may have an effect on the way the vaccine works e.g. lack of protein affects the production of antibodies.

Question 9

What are the ethical considerations on the development and implementation of a vaccine?

Answer 9

The testing of the drug on animals and unaffected individuals.

Whether it is cost effective or not.

Whether the vaccine should be optional or forced.

Whether benefits out weight the risks and side effects.

The legitimacy of vaccination programmes.

Question 10

What’s HPV?

What is the vaccine?

Answer 10

The human papilloma virus, which can lead to cancer, warts and verrucas, spread through direct contact e.g. sexual intercourse.

A vaccine has been produced, protecting against most HPV strains. It’s a subunit vaccine made up of the antigens/proteins on the pathogen’s surface. There is no DNA so infection cannot occur.

Question 11

What are antibiotics?

Answer 11

Chemicals which either kill bacteria or slow their growth. They work on bacteria (prokaryotes) but not viruses.

Question 12

What are bacteriocidal antibiotics?

Answer 12

Antibiotics which kill bacteria by either preventing cell wall synthesis or disrupting protein synthesis within the bacteria.

Question 13

How does penicillin work?

Answer 13

It’s a bacteriocidal drug which prevents the synthesis of peptidoglycan, which makes up bacterial cell walls so prevents new cell walls forming so that the cell bursts.

Question 14

How does polymyxin B work?

Answer 14

It’s a bacteriocidal drug which damages the plasma membrane of the bacterial cell so the contents leaks out, done by targeting phospholipids not found in eukaryotic cells.

Question 15

What are bacteriostatic antibiotics?

Answer 15

Antibiotics which prevent the growth and reproduction of bacteria, but do not kill them.

Question 16

How does tetracycline work?

Answer 16

It’s a bacteriostatic antibiotic which interferes with the bacterial protein synthesis by preventing further transfer RNA from binding to ribosomes.
The bacteria survives but cannot replicate.

Question 17

What are sulfonamides?

Answer 17

Competitive inhibitors of the bacterial cell’s metabolism.
Mammalian cells take up folic acid as a dietary vitamin. Bacterial cells have to synthesise folic acid and the sulphonamides inhibit the enzymes in this pathway.
In the absence of folic acid, purines and hence DNA cannot be synthesised.

Question 18

What does erythromycin do?

Answer 18

It prevents protein synthesis by blocking one of the sites on the ribosome, which prevents the polypeptide chain from elongating.

Question 19

What are broad-spectrum and narrow-spectrum antibiotics?

Answer 19

Broad - work against a wide range of bacteria

Narrow - only effective against specific bacteria e.g. gram positive or negative

Question 20

What causes bacterial resistance against antibiotics?

Answer 20

Mutations e.g. mutation on the genome or due to the genes on the plasmid.
Examples include MRSA and MDR-TB.

Question 21

What has led to the increase in resistance / bacterial mutations?

Answer 21

Excessive / overuse of antibiotics.

Failure for patients to complete the course of a vaccination programme (e.g. boosters).

The use of antibiotics in animal feed.

Question 22

What does a vaccination involve?

Answer 22

A deliberate exposure of antigens of a foreign source, e.g. a pathogen, to an individual to provoke the immune response and provide immunity.

They can be administered by injection or orally.