S5 Infection Prevention Flashcards
What are some examples of sources for e.g. Legionella pneumophilia, food poisoning organisms, rabies?
Legionella - environmental
Food poisoning - food/water
Rabies - animals
How can infections be spread?
- From a common source (then person to person)
- Person to person (direct)
- Person to person (indirect - via a vector)
What are 3 examples of direct person to person spread?
- influenza
- norovirus
- Neisseria gonnorrhoea
What is an example of indirect person to person spread?
Mosquitos spreading malaria (person to person)
What is an endemic disease?
The usual background rate of cases
What is an outbreak?
Two or more cases linked in time and place
What is an epidemic?
A rate of infection that’s greater than the usual background rate
What is a pandemic? What sort of pathogen causes this?
A very high rate of infection spreading across many regions/countries/continents
A novel one - one no one is initially immune to
What is R0?
The average number of cases one case generates over the course of its infectious period, in an otherwise uninflected, non-immune population
What does it mean if R0 is more than 1?
There is an increase in cases
What does it mean if R0 is equal to 1?
There is a stable number of cases
What does it mean if R0 is less than one?
There is a decrease in cases
What are the reasons for outbreaks, epidemics and pandemics?
- new pathogens - antigens, virulence factors, antibacterial resistance
- new hosts - non-immunes, healthcare effects
- new practice - social, healthcare
What factor determine transmissibility of a pathogen? How does this vary?
The infectious dose - the number of microorganisms needed to cause an infection
Varies by microorganism, presentation of microorganism and immunity of potential host
What does an epidemic curve shape look like (number of people infected at each time interval vs time)? What are the 3 stages?
A bell-shaped curve
Susceptible, infected, recovered
How can a small scale outbreaks curve be defined?
Stochastic - random distribution/pattern (can be analysed with stats but may not be predicted precisely)
Where in the infection model can interventions be applied?
- pathogen causing infection with patient
- patient causing infection with pathogen
- pathogen and patient but without infection
What interventions can be applied to the pathogen/vector?
Reduction or eradication
- antibacterials (incl. disinfectants)
- decontamination
- sterilisation
- eliminate vector breeding sites
What interventions can be applied to the patient?
Improved health
- nutrition
- medical treatment
Immunity
- passive - maternal antibodies, intravenous immunoglobin
- active - vaccination
What interventions can be applied to the practice?
- behavioural - are sex, safe disposal of sharps, food/drink prep
- change
- protective equipment - clothing and equipment (long sleeves, PPE)
- geographic - avoid area where pathogen is prominent
What interventions can be applied to the place?
Environmental engineering
- safe water
- safe air
- good quality housing
- well designed healthcare facilities
What are the good consequences of controlling an infection?
Decrease incidence/elimination of a disease/organism e.g. small pox, polio, dracunculiasis
What are the bad consequences of controlling an infection?
- decreased exposure to a pathogen —> deceased immune stimulus —> decreased antibody —> increased susceptibles —> outbreak
- leads to a later average age of exposure when severity is increased e.g. polio, chickenpox, hepatitis A
