3.1 Communicable Diseases PART 2

Question 1

What is a vaccination?

Answer 1

Contains a dead or inactivated form of the pathogen which stimulates white blood cells to produce complementary antibodies to the pathogen.

In the case of a second infection, memory cells can rapidly produce the correct antibodies and prevent illness.

Question 2

What is herd immunity?

Answer 2

If a sufficiently high proportion of a population are immune to a disease (especially through vaccination), the spread of this disease will be limited.

Question 3

What are the advantages of vaccinations?

Answer 3

● They have eradicated many deadly diseases eg. smallpox.
● Many epidemics can be prevented by vaccinations.
● Herd immunity protects those who cannot have vaccinations.

Question 4

What are the disadvantages of vaccinations?

Answer 4

● Not guaranteed to work - might not protect against multiple strains of a pathogen.
● May be side effects or adverse reactions.

Question 5

What drugs are used to cure some bacterial diseases?

Answer 5

Antibiotics - they can kill bacterial pathogens inside the body.

Question 6

How do antibiotics work?

Answer 6

Antibiotics eg. penicillin kill bacterial pathogens inside the body, but do not kill human cells. Whilst some antibiotics kill a wide range of bacteria, it is important that the right antibiotic is used for specific bacteria.

Question 7

Why can antibiotics not be used to treat viral diseases?

Answer 7

Antibiotics have no effect on viral pathogens as they live inside the host’s (human) cells. Therefore, it is difficult to design drugs that would kill the virus and not destroy human cells at the same time.

Question 8

What is antibiotic resistance?

Answer 8

Antibiotic resistance occurs when mutations lead to individual bacteria being resistant to an antibiotic.

These bacteria are able to survive, reproduce and pass on their alleles, leading to a greater proportion of antibiotic-resistant bacteria.

This is concerning as some types of bacteria are becoming resistant to all known antibiotics, so the diseases that they cause cannot be cured.

Question 9

How can we prevent antibiotic resistance?

Answer 9

● Avoid overuse and unnecessary use of antibiotics - eg. antibiotics are often used for viral infections.
● Finish antibiotic courses - to ensure all bacteria is killed.

Question 10

What effect do painkillers have on infectious diseases?

Answer 10

Painkillers can only treat the symptoms but do not kill pathogens

Question 11

What plant is the heart drug digitalis extracted from?

Answer 11

Foxgloves

Question 12

What painkiller originates from a compound found in willow bark?

Answer 12

Aspirin

Question 13

What antibiotic was discovered by Alexander Fleming from a type of mould?

Answer 13

Penicillin

Question 14

What are the four qualities of a good medicine?

Answer 14

● Effective
● Safe
● Stable
● Able to be taken in and removed easily

Question 15

What three main factors are tested for when developing new drugs?

Answer 15

● Toxicity
● Efficacy
● Dose

Question 16

How is preclinical testing carried out?

Answer 16

In a laboratory - uses cells, tissues and live animals

Question 17

How is clinical testing carried out?

Answer 17

Uses healthy volunteers and patients. Firstly, the drug is tested at a low dose on healthy people - then tested on patients and on a larger scale to find the optimum dose.

Often, one group receive a placebo (not the test drug) and the other group receive the actual drug, in order to assess its efficacy.

Question 18

What is the difference between a single-blind and a double-blind trial?

Answer 18

In a single-blind trial, only the doctor knows whether the patient is receiving the drug or the placebo.

In a double-blind trial, neither the patient nor the doctor knows.

Double-blind trials help remove bias on the part of the doctor.

Question 19

What is a peer review?

Answer 19

Where the results of drug trials are checked over by scientists knowledgeable in this field.