Outbreaks Year 2 Pop Block 3

5 phases of outbreak investigation

• describe the outbreak

• collect and analyze data

• implement control

• follow-up

• communication

do the 5 phases need to happen in order?

no, but all need to happen

outbreak definition

higher than expected number of cases

What is necessary to know to detect change and move forward?

• number of cases

• population at risk

• agents causing disease

• details of cases

  • singalment, timeline, signs, and symptoms

attack risk

cases/population at risk

morbidity

sick cases/population at risk

case fatality rate

dead cases/cases

case definition

• set of criteria that individual must meet to be counted as ill in this outbreak

• individuals we will do something with

• must be specific enough to exclude cases not due to this outbreak

• must be sensitive enough to include those with disease

• must be practical to use

• must include: who (individuals), what (pathogen, syndrome, test result), modifiers (other things that identify those at risk)

can you change your case definition?

yes

population at risk

• individuals who could be or become cases in this outbreak based on current information

• who you want to observe for cases and target for control measures

• changes over course of an outbreak

  • before you have information, anyone is at risk

  • once you narrow down source, then fewer are at risk

  • sometimes when you know source, more are exposed than initially thought

all cases must be

members of population at risk

describe the outbreak includes

defining case and population at risk

epidemic curve

point source curve

propagated curve

sporadic curve

seasonal curve

patterns in epidemic curves

endemic or epidemic

endemic patterns

• variation around a constant

• seasonal

• expected

epidemic patterns

• point source

• propagated

• sporadic

• unexpected

what is mean incubation period in point source curve

time from index case or common exposure to exposure peak