Infection Prevention Flashcards
What are the two main ways infections are spread?
Most infections are transmissible from a non-human to humans and also from humans to humans both directly and indirectly (i.e. via a vector such as the mosquito in malaria).
Define: Endemic disease, outbreak, epidemic and pandemic
Endemic Disease – the usual background rate
Outbreak – two or more cases linked in time and place
Epidemic – a rat on infection greater than the usual background rate
Pandemic – very high rate of infection spreading across many regions, countries continents
What is the reproductive number?
R0 – the average number of cases on case generated over the course of tis infectious period, in an otherwise uninfected, non-immune population.
What are the 4 P’s describing reasons for outbreaks
Pathogen (new) – with different antigens (antigenic shift in influenza), virulence factors and antibacterial resistance
Patient – New hosts which are not immune or health care effects
Practice – both social and healthcare related e.g. introduction of new risks such as surgery or new obsessions such as ear piercing.
Place – entering a new place influencing all the above factors
What factors effect transmission?
Infectious dose – number of micro-organisms required to cause infection. Varies by micro-organism, presentation of micro-organism and immunity of potential host.
What are epidemic curves?
If there is an outbreak we usually get a standard curve as the number of people infected increases peaks and then drops back to almost none. This is as people start susceptible, then move to infected and after that become recovered and hopefully immune.
At what 3 stages can we attempt to prevent an infection?
Preventing the pathogen from existing, preventing infection of the patient or prevent spread from that patient.
Describe how we intervene at the 4 P’s to prevent infection
Pathogen (+vector) – reduction or eradication – antibacterials, decontamination and sterilisation or reduce/eradicate the vector spreading the pathogen
Patient – improved health immunity – nutrition, medical treatment, passive (maternal antibody and intravenous immunoglobulin) and active immunity such as vaccination
Practice – behavioural change, protective equipment – avoidance of pathogen by not going somewhere, protective equipment in hospitals, behavioural such as safe sex, safe disposal of sharps and food and drink protection
Place – environmental engineering – safe water, safe air, good quality housing and well-designed healthcare facilities.
What is Herd immunity?
Herd immunity – when a certain percentage of the population is vaccinated, those that are can protect those that aren’t from anyone who is infected and so spread is prevented.
What are the consequences of controlling infection transmission?
Decreased exposure - decreased immune stimulus - decreased antibodies - increased susceptibility - outbreaks.
Later average age of exposure - increased severity such as in Polio, hepatitis A, chicken pox and congenital rubella syndrome.
What are the good consequences of controlling infection transmission?
Good Consequences – decreased incidence of certain diseases or even elimination such as with small pox, polio and Dracunculiasis.
Why is Surveillance important?
Surveillance of what infections are occurring in society is important for predicting prevention tactics that need to be implemented, improved or started.
