Lecture 14 - Infection Prevention Flashcards
How can infections be spread?
From a non human source to humans
From person to person (directly or indirectly)
What is an example of an environmental source of infection?
Legionella pneumophila
What is an example of an infection from a food or water source?
Escherichia coli
Salmonella
Listeria (meningitidis)
What is an example of an animal source of infection?
Rabies
What are some examples of direct person to person infections?
Influenza
Norovirus
Neisseria gonorrhoea
What are some examples of in-direct person to person infections?
Mosquitos infecting humans with Malaria
What is endemic disease?
The usual background rate of disease that generally occurs in that area
What is an outbreak?
When 2 or more cases are linked in time and place
What is an epidemic?
When the rate of an infection is greater than the usual background rate
What is a Pandemic?
When theres a very high rate of infection spreading across many regions, countries, continents
What is the Basic Reproductive number (R0)?R number
The average number of cases that one case generates over the course of its infectious period in an otherwise uninflected non immune population
What happens if the reproductive number (R0) = 1?
R0 = 1?
Stable number of cases
What happens if R0 > 1?
Increase in the number of cases
What happens if R0 < 1?
Decrease in the number of cases
What is Legionella pneumophilla?
Gram negative bacteria
Lives in water
How is Legionella pneumophila spread?
Inhaled via droplets from the environment
Not spread from person to person, from contaminated water source
What is faecal oral transmission?
Ingestion of faecal matter
How is norovirus transmitted?
Faecal oral transmission
Possibly airborne too
What are the 4Ps?
4 reasons for outbreaks:
Patient
Pathogen
Practice
Place
How may Pathogen factors cause outbreaks, epidemics or pandemics?
Antigens
Virulence factors
Antibacterial resistance
How may Patient factors cause outbreaks, epidemics or pandemics?
New hosts due to people not being immune
How may Practice factors cause outbreaks, epidemics or pandemics?
New things people may do
What determines transmissibility of an infection?
Infectious dose (num of microbes needed to cause infection)
What determines infectious dose?
Microorganism
Immunity of the potential host
Describe the usual shape of an epidemic curve and why its like this?
Bell shaped curve
Initially everybody is susceptible so number of people getting infected will keep increasing until a certain point
From here less people are susceptible so less and less people get infected until the population has near enough fully recovered
What is meant be stochastic nature?
Random
Not a predictable
What is the term used to describe the way that small scale outbreaks may occur?
Stochastic nature
What can be done to prevent infection at the pathogen level?
Prevent the pathogen from entering a population
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What can be done at the patient level to prevent infection?
Improve general health of population
Immunity (vaccinate)
What can be done at the practice level to prevent infection?
Behaviour changes
PPE
What can be done at the place level to prevent infection?
Environmental engineering
Separating sewage areas from drinking water areas
How can pathogens and vectors be reduced/eradicated?
Antibacterial
Decontamination
Sterilisation
Eliminate vector breeding sites
How can we improve patients health?
Better nutrition
Better medical treatment
What is herd immunity?
Protection produced by most of the population being immune to a disease making person to person transmission very difficult
This protects the non immune
What practice interventions can be done to prevent infection?
Avoid a place/vector so dont go there
Protective clothing
PPE
Safe sex
Good food and drink prep
What place interventions (environmental engineering) things can be done to prevent infection?
Safe water
Safe air
Good quality housing
Well designed health care facilities
What is good about controlling /preventing infections?
Decreased incidence or elimation of a disease/organism
What is BAD about controlling /preventing infections?
Decreased exposure to pathogen
Decreased immune stimulus
Decreased frequency of antibody
More susceptible individuals
Can lead to outbreaks
