BMS2052 Study Guide - Final Guide: Filoviridae, Flavivirus, Causal Inference
4 May 2018
School
Department
Course
Professor
Epidemiology and public health
Frequency: No. of cases in relation to
population size.
Pattern: occurrence of health related events
by time, place and person.
Characterise health events by time, place and
person are for descriptive epi.
Looking for determinants finding how and
why is analytical epi.
Studies look at both communicable and non-
communicable disease. And the focus is on
the population.
Prevalence: a quantity of cases at a given
time
Incidence: rate of new cases.
Descriptive epi: observational, are used to
generate hypothesis. This is to characterise
events to see if something different eg an
outbreak. Can use group data or individual
data. Eg descriptive cross-sectional.
Analytical epi: experimental and
interventional. A key feature – comparison
groups. These can also be observational eg
ecological, cohort, cross-sectional case-
control. Mostly uses experimental data from
groups or individuals – community trial,
individual clinical or field trial. These describe
an association between an exposure and
outcome.
Cohort – observational & analytical. These
are good for rare exposures. Establish a
temporal relationship which is good for causal
inference. Vaccine effectiveness can be
tested. This is comparing the disease outcome
over time in indiviudals with exposure to
those without exposure. Is both prospective
and retrospective.
Case-control – observational & descriptive &
analytical. Looking at several exposures,
testing current hypotheses. Note that there is
lots of bias. This is looking back in time and
comparing exposures in disease cases vs
healthy controls from the same population
exposure data collect data retrospectively
Cross-sectional – observational & analytical
& descriptive is to find prevalence. Surveys
exposures and diseases at a single point in
time.
Ecological – observational & analytical &
descriptive is for hypothesis generation – uses
secondary data.
RCT – experimental & analytical. Drugs vs
placebo.
We use studies to determine Temporality.
INFECTIOUS DISEASES
A host is an organism that is susceptible to
the agent.
Indirect modes of transport include airborne,
vector borne, vehicle borne and water borne.
Host to host transmission can be vertical
(hereditary) or horizontal (non-hereditary).
Hyperendemic = constant presence in at high
incidence/ prevalence and affects all ages
equally.
Holoendemic = high prevalence early in life,
effects children eg malaria.
Transmission of infectious agents follows the
path: source portal of exit portal of
entry.
Salmonella enterica
Local: gastroenteritis
Systemic: typhoid
Ebola filovirus
note that post epidemic surveillance
increases.
Zika Flavivirus
CAUSES/ CAUSATION
A cause is a factor/ agent that plays an
essential role in producing an occurrence of
the disease outcome
positive: it causes disease
negative: absence causes disease
Sufficient: inevitably results in outcome
Necessary: outcomes only occur id factor is
operated (i.e is present in all conditions)
Document Summary
Frequency: no. of cases in relation to population size. Pattern: occurrence of health related events by time, place and person. Characterise health events by time, place and person are for descriptive epi. Looking for determinants finding how and why is analytical epi. Studies look at both communicable and non- communicable disease. Prevalence: a quantity of cases at a given time. Descriptive epi: observational, are used to generate hypothesis. This is to characterise events to see if something different eg an outbreak. These can also be observational eg ecological, cohort, cross-sectional case- control. Mostly uses experimental data from groups or individuals community trial, individual clinical or field trial. These describe an association between an exposure and outcome. Establish a temporal relationship which is good for causal inference. This is comparing the disease outcome over time in indiviudals with exposure to those without exposure.
