Session 8 - Infection prevention Flashcards
Give three different mechanisms of infection
- Common source
- Person-to-person direct
- Person-to-person indirect
Give three examples of common sources and the infections associated
- Food/water - Food poisoning organisms
- Environmental - Legionella Pneumophilia
- Animals - Rabies
Give three examples of person to person direct infection
- Influenza
- Norovirus
- Neisseria Gonnorhoeae
Give three examples of person to person indirect transmission (involved a vector)
- Mosquitos - Malaria, dengue
- Cats - Toxoplasmosis
- Ticks - Lyme disease, spotted fever
What is an endemic disease?
• The usual background rate
What is an outbreak?
• Two or more cases linked in time and place
What is an epidemic?
A rate of infection greater than the usual background rate
What is a pandemic?
Very high rate of infection spreading across many regions, countries and continents
What is a basic reproduction number?
The average number of cases one case generates over the course of its infectious period, in an otheriwse uninfected, non-immune population
What if Ro>1?
Increase in cases
If Ro=1?
• Stable number of cases
What if Ro <1?
• Decrease in cases
Give three reasons for outbreaks
- New pathogen
- New hosts (compromised immunity, healthcare effects)
New practice
What is an infectious dose?
Number of micro-organims required to cause infection
Give an organism with a high infectious dose
• Salmonella - Requires >10^5 organisms
Give an organism with a low infectious dose
• Escherichia coli - Very low <10 organisms
Give three factors which vary the necessary infectious dose
- Micro-organism
- Presentation of micro-organism
- Immunity of potential host
What are the four P’s of infection?
- Pathogen
- Patient
- Practice
- Place
How do you reduce outbreaks due to pathogens?
• Reduce/eradicate pathogen ○ Antibacterials including disinfectants ○ Decontamination ○ Sterilisation • Reduce/eradicate vector ○ Eliminate vector breeding sites
How do you reduce outbreaks due to patients?
• Improved health immunity ○ Passive ○ Active • Improved health ○ Nutrition ○ Medical treatment
What is passive immunity?
Passage of maternal antibodies across placenta
Why does the incidence of meningitis increase dramatically at three months after birth
• Newborns have immunity from mothers antibodies up to that point
How do you reduce outbreaks due to practice?
• Behavioural change
How do you reduce infections due to place?
- Environmental
* Engineering
