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Flashcards in epidemiology in practice Deck (29)
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1

passive surveillance

based on reports from health care workers

2

active surveillance

all cases are reported by a system that is set up for this reason

3

sentinel surveillance

we look for trends in disease in certain sites instead of covering whole population

4

what influences spread of disease

properties of agent, sources of infection, biological reservoirs, host factors, exposure variation, environment

5

infectivity

ability of an organism to invade and multiply in a host

6

methods of transmission

direct (touching or inhaling secretions), indirect (vehicle), airborne (droplet nuclei)

7

development of disease

Infection, Incubation (latent --> infectious period), Clinical disease (infectious period), Recovery

8

epidemic

unexpected increase in incidence of disease in one area/group

9

endemic

constant presence of disease or infectious agent within a geographical area of population group

10

pandemic

unexpected increase in incidence of disease that cross international boundaries

11

cluster

greater aggregation of relatively uncommon events or disease in space and or time that are thought to be greater than due to chance

12

primary case

1st person infected

13

index case

the first person recognised by health authorities that makes them aware an outbreak is occurring

14

2nd generation

next people infected from primary case

15

secondary attack rate

how many people the primary infects

16

common source

when everyone gets outcome from same common source e.g. Arana serving dodgy chicken once. Epidemic curve has triangular shape

17

continuous source

continuous exposure e.g. local well infected with virus. Epidemic curve has long flat shape

18

intermittent source

repeated common common source e.g. arana serving dodgy chicken 3 times a week

19

propagated source

one person spreads it to another etc

20

mixed source

starts as common source then develops into propagated source

21

what is screening

widespread use of a simple test for a disease in an apparently healthy (asymptomatic) population

22

what is a screening programme

organised system using a screening test among asymptomatic people in the population to identify early cases of disease in order to improve outcomes

23

what is a screening test

a test, usually relatively cheap and simple, used to test large numbers of apparently healthy people to identify individuals suspected of having early disease who will then go on to have further diagnostic tests to confirm the diagnosis

24

lead time

time from when disease is detectable and when symptoms appear

25

criteria for screening

disease is chronic and serious, has high prevalence, long lead time, can improve length or quality of life, change course of disease

26

what is sensitivity

  • Proportion of people with the disease who test positive
  • true positive/(all with disease)
  • Test specific
  • High = good

27

what is specificity

  • Proportion of people without the disease who test negative
  • True negative/(all without disease)
  • Test specific
  • High = good

28

what is tradeoff between sensitivity and specificity

have to Consider consequences of missing cases (false negatives) versus false alarms (false positives).

if disease is severe then should maximise sensitivity.

if test expensive then should maximise specificity

29