Infection Prevention Flashcards
Many infections are transmissible and common sources may be found that lead to a lot of cases. Please give some examples of non-human to human infection sources.
Environment - Legionella pneumophilia (no onwards transmission).
Food/wate - food poisoning organisms with inwards transmission possible.
Animals - rabies, with possible onwards transmission.
Give some examples of direct and in-direct person to person acquired infections.
Direct: Influenza Norovirus, Neisseria gonorrhea.
Indirect person to person requires a vector: female mosquitos and malaria.
What are the 4 possible consequences of transmission?
Endemic, outbreak, epidemic or pandemic.
What’s the difference between endemic and epidemic?
If a disease is endemic, it’s just at its usual background rate, whereas if there’s an epidemic, the rate of infection is greater than the usual endemic rate.
What constitutes an outbreak of an infection?
Two or more cases linked in time and place, plausibly connected.
What does it mean if there is a disease pandemic?
A very high rate of infection spreading across many regions, countries or continents, often by novel microorganisms.
Define the Basic Reproductive Number - R0. What can be told from it?
The average number of cases one case generates over the course of its infectious period, in an otherwise unaffected, non-immune population.
If R0<1–> decrease in cases, R0>1–> increase in cases or R0=1–> there’s a stable number of cases.
The 4Ps of infection prevention can help explain reasons for outbreaks, epidemics and pandemics. How is this so for ‘pathogen’?
A new pathogen - antigens (antigenic drift/shift), virulence factors and antibacterial resistance may cause an outbreak.
The 4Ps of infection prevention can help explain reasons for outbreaks, epidemics and pandemics. What about patients explains outbreaks?
New hosts/patients, may be non-immune and have healthcare effects.
New practises, socially and healthcare wise may lead to infection outbreaks, but how is place connected?
Place may encompass, the pathogen, patient and practise.
One factor determining transmissibility if an infection, is the infectious dose. Explain.
The infectious dose is the number of microorganisms required to cause infection, which varies by microorganism, as well as its presentation and the immunity of the potential host.
Epidemic curves are ______ shaped and show the number of people ___________ at different time intervals. People go from being susceptible, to infected, then ___________. An example is Norovirus outbreak reports, with peaks corresponding to _________ months.
Bell
Infected
Recovered
Winter
In which case will outbreaks not show the normal epidemic curve?
The stochastic nature of small scale outbreaks mean that they may not show the normal epidemic curve, as can be explained by probability and chance.
How can pathogens be interfered with to prevent outbreaks?
Pathogens (+/- vector) may be reduced or eradicated with antibacterials, including disinfectants. There’s also decontamination, sterilisation and elimination of vector breeding sites.
What patient interventions may occur to prevent infections?
Improve health (nutrition, medical treatment) and immunity - passive e.g. Maternal antibodies, IV immunoglobulins or active via vaccination.
Herd immunity provides indirect protection for those not ____________. The proportion of the population that needs to be vaccinated depends on the R0 (________ ____________ __________).
Vaccinated
Basic reproductive number
What interventions can occur with practice, to prevent infections?
Avoidance of a pathogen/its vector, geographically or with protective clothing/equipment (long sleeves and trousers for mosquito bites or personal protective equipment in hospitals-gowns, gloves and masks). Also behavioural interventions, such as safe sex, appropriate disposal of sharps, food and drink preparation.
What about a place can benefit from an intervention, in terms of infection prevention?
Environmental engineering: safe water and air, good quality housing and well designed healthcare facilities.
Infection prevention control requires multi-disciplinary skills - ‘from genes to latrines’ and surveillance is important. List some good and bad consequences of infection control.
Good: decreased incidence/elimination of a disease/organism (e.g. Smallpox, polio, guinea worm).
Bad: decrease exposure to a pathogen means decreased immune stimulus and so decreased antibodies, meaning increased susceptibilities, which could lead to an outbreak or later age of exposure, which can result in increased severity (Polio, Hep A, chicken pox, congenital rubella syndrome).
