Infection Prevention Flashcards
What is an example of a pathogen that can be transmitted environmentally but not from person to person?
Legionella pneumophila
What is an example of an infection that is transmitted from animal to person?
Rabies
What are some examples of pathogens that are transmitted from person to person directly?
Influenza, Norovirus, Neisseria gonorrhoea
What is an example of an infection that is transmitted from person to person indirectly?
Malaria (use of mosquitos)
What is meant by endemic disease?
Usual background rate
What is meant by an outbreak?
Two or more cases linked in time and place
Has to be some plausible connection between two cases
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, continents
What is antigenic shift?
Antigenic shift is the process by which two or more different strains of a virus, or strains of two or more different viruses, combine to form a new subtype having a mixture of the surface antigens of the two or more original strains.
What is antigenic drift?
Antigenic drift is a mechanism for variation in viruses that involves the accumulation of mutations within the genes that code for antibody-binding sites.
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 happens to the number of cases if R0 > 1?
Increase in cases
What happens to the number of cases if R0 = 1?
Stable number of cases
What happens to the number of cases if R0 < 1?
Decrease in cases
What is the infectious dose?
Number of micro-organisms required to cause infection
What interventions can be made in the transmission of infections?
Reduce/eradicate pathogen - antibacterials, decontamination, sterilisation
Reduce vector (mosquito spray, eliminate vector breeding sites)
Improved health of patient, nutrition, immunity
What is herd immunity?
The resistance to the spread of a contagious disease within a population that results if a sufficiently high proportion of individuals are immune to the disease, especially through vaccination.
“the level of vaccination needed to achieve herd immunity varies by disease”
How can practices be changed to reduce infection spread?
Avoidance of pathogen (geographically, protective clothing)
Behavioural (safe sex, safe disposal of sharps, safe food and drink preparation)
What are the positive consequences of infection control?
Decreased incidence or elimination of disease/organism
What are the negative consequences of infection control?
Decreased exposure to pathogen -> decreased immune stimulus -> decreased antibody production -> increased susceptibility -> outbreak
Also, later average age of exposure so increased severity of infection (eg in polio, hep A, chicken pox)
