Infection Prevention

Question 1

How could an infection be transmitted indirectly from person to person? Given an example

Answer 1

Via a vector e.g mosquito - malaria

Question 2

Give an example of a food/water transmissible infection

Answer 2

Food poisoning - EColi

Question 3

Give an example of an environmentally transmitted infection

Answer 3

Legionaries

Question 4

Give an example of person-to-person transmission

Answer 4

Influenza, Norovirus

Question 5

Give an example of animal transmission

Answer 5

Rabies

Question 6

Define endemic disease, outbreak, epidemic, pandemic

Answer 6

Endemic - normal background rate of disease
Outbreak - two or more new cases linked in time and place
Epidemic - A rate of infection greater than the usual background rate
Pandemic - Very high rate of infection spreading across many regions/countries/continents

Question 7

What is R0? High R0? Low R0? At what R0 would an infection outbreak self terminate?

Answer 7

R0 is the average number of cases one case generates over the course of it’s infectious period, in an otherwise uninfected, non-immune population. Higher R0 = increase in cases, Below R0 - 1 is a decrease in cases. Below 1 an outbreak will self-terminate

Question 8

What are the 4 Ps of infection spread?

Answer 8

Pathogen
Patient
Place
Practice

Question 9

How can a pathogen change cause an outbreak/epidemic/pandemic (3)?

Answer 9

• Change in virulence factors
• Change in antigens
• Antibacterial resistance (mutation)

Question 10

How can patients (hosts) cause outbreaks?

Answer 10

Non-immunes - e.g. immunosuppressed, healthcare effects e.g. HAI outbreaks

Question 11

How can practice cause outbreaks?

Answer 11

New practices

Question 12

Define infectious dose. What can affect the infectious dose?

Answer 12

Number of organisms required to cause infection. Can change with person (immunity), presentation (how infected), and different microorganisms have different infection doses

Question 13

Give an example of an organism that requires a high infectious dose, and a low one

Answer 13

High - Salmonella

Low - E Coli

Question 14

What does a typical epidemic curve look like?

Answer 14

A bell curve

Question 15

How can you use the 4Ps to intervene and control infection outbreaks?

Answer 15

Pathogen - reduce/eradicate pathogen/vector - e.g. antibacterial, sterilisation
Patient - improved health and immunity
Place - environmental engineering e.g. cleanliness/safe water/well designed healthcare facilities
Practice (behaviour)- protective equipment, change behaviour e.g. aseptic technique, don’t go to a country, wear long sleeves to prevent mosquitos

Question 16

How does sterilisation reduce infection?

Answer 16

Removes pathogen

Question 17

How can you improve someones immunity to an infection?

Answer 17

Vaccination

Question 18

What is herd immunity? Is it the same for all infections or do some require increased immunity to prevent spread?

Answer 18

Herd immunity is where resistance to spread of a disease in a population (mostly through vaccination) results in a sufficiently high proportion of people that are immune to stop the spread of disease. The % vaccinated to achieve this is different depending on the disease e.g. measles highly contagious need high her immunity, flu less so.

Question 19

What are some positive and negative consequences of infection control?

Answer 19

Positive - reduced outbreaks/elimination e.g. small pox

Negative - reduced immunity as reduced exposure –> decreased antibodies –> leads to outbreak

Question 20

What is legionnaires disease?

Answer 20

Atypical type of pneumonia caused by legionella pneumoniae