Epidemiology - Quiz 1-1

sespi's version from 2016-02-04 00:34


Question Answer
What is CDC?Centers for Dz Control & Prevention (If you get this wrong, I swear... )
What is OIE?World Organization for Animal Health (known by its French acronym Office International des Epizooties – OIE) ((bc calling it WOAH sounded silly)
What is USDA-APHIS?United States Department of Agriculture - Animal & Plant Health Inspection Service
What is USDA-FSIS?United States Department of Agriculture - Food Safety & Inspection Service (remember the other 1? Animal & Plant!)
What is AVMA?American Veterinary Medical Association (If you get this wrong Slenderman will eat ur entire family, children first)
Epidemiology is?The Greek of the word means... "The study(ology) of what is upon(epi) them(dem) (the population)". SO, it is the study of the occurrence & distribution of dz in populations (animal or human) (Emphasis on establishing the causal factors that influence dz occurrence)
What is a population?The totality of individuals that share common attributes (sex, breed, ethnicity, location)
What is EBM (Evidence Based Medicine)?"The conscientious, explicit & judicious use of current best evidence in making decisions about the care of the individual PTx.”
EBM uses POPULATION DATA to better understand these 4 areasDx
What is Endemic (human) / Enzootic (animal)?Usual (constant) frequency of dz in a population. A dz is endemic when it occurs w/ predictable regularity in a population. (Note: Endemics can become epidemics if host-agent-environmental factors change)
What is Epidemic (Epizootic)?Often synonymous w/ the term "outbreak" & typically used for infectious Dzs. An epidemic is a dz that is rapidly spread & many individuals acquire dz over a short period
What is Pandemic?A widespread epidemic/epizootic……involving more than 1 country. There is a more specific def. made by the WHO (World Health Organization), which requires...: There must be a dz new to a population – or at least a dz that had not surfaced for a long time. This dz must be czd by dz-causing agents that infect humans, czing serious illness. AND, the agents must spread easily & sustainably among humans causing high morbidity & high mortality
The WHO (World Health Organization) defines their "Phase 6-Pandemic phase" asThe pandemic phase, is characterized by community level outbreaks in at least 1 other country in a different WHO region in addition to the criteria defined in Phase 5. Designation of this phase will indicate that a global pandemic is under way
"Sporadic" Dz occurrence is defined as...A dz that is NOT NEW & occurs infrequently (w/o regularity) in a population. Cases occur in small numbers, illness is not apparently connected w/ similar illnesses in any other animals/persons & it is not rapidly spread
Explain Epidemic vs SporadicWhilst an epidemic can be 1 case of a new Dz, it is rapidly spread btwn animals /humans...
A sporadic case refers to a person/animal whose illness is NOT rapidly spread & NOT apparently connected w/ similar illnesses in any other animals or humans
What is public health surveillance?Public health surveillance is the ongoing, systematic collection, analysis, interpretation & dissemination of data regarding a health-related event for use in public health action to reduce morbidity & mortality & to improve health (CDC, 2001).
What is passive surveillance?System in which Vet agencies make no active efforts to collect dz info (But Problem: Some info on dz frequency but not accurate due to poor reporting)
What is active surveillance?Uses structured dz surveys to collect high quality dz info quickly. A survey: Trained veterinary staff examine only a sample of the population. (More costly but more accurate)
What is a host?An individual (animal or human) that harbors an infectious agent or is exposed to a potential causal agent of dz which is usually infectious. Typically used in reference to infectious dzs altho in general hosts are also susceptible to noninfectious & chronic dzs.
What is a demographic?Personal characteristics of an individual or group (age, sex, breed, occupation)
What is a case?Individuals w/ a particular dz that meet selected criteria stated by the case definition
What are causal factors or determinants?Factors that directly influence the occurrence of dz. Synonymous w/ risk factor or exposure factor
What is infxn?Defined as the encounter of a potentially pathogenic agent w/ a susceptible human /animal host & the host shows an immunologic response to infxn
What is disease DEFINED as?A clinically apparent infxn — infxn accompanied by overt illness

Dz Reporting

Question Answer
What are the 3 corners of the epidemiologic triangle? What is this triangle used for?Host-Agent-Environment. It is used as a model to explain why dzs occur in a population.
Temporal (in time) dz occurrence reporting uses what kinda terminology (list...)Endemic (Enzootic)
Epidemic (Epizootic)
Pandemic (Panzootic)
How would you describe endemic in terms of temporal patterns?Dz occurs at expected frequency, present in population or region at all times & usually low & at a predictable level
How would you describe epidemic in terms of temporal patterns? How do you depict the occurrence of the dz?Dz occurs at greater than expected frequency. Occurrence depicted graphically as "Epidemic curves"
How would you describe pandemic in terms of temporal patterns?Sporadic
The shape of an epidemic curve tells us what 2 major things?These are histograms depicting the # of new cases ((Y) axis) over time ((X) axis). Using this, we can get info on probable time of exposure based on the incubation period & also info on if the outbreak was due to a common or point source
What are the 3 basic curves of dz occurrence on the epidemic curve?(1) Point epidemic (point source)
(2) Continuous common source epidemic
(3) Propagating epidemic
What is a "point source" epidemic curve? What does the curve look like on the graph?Animals or persons are subjected to the same BRIEF exposure over a limited, defined time period, usually w/in 1 incubation period. The graph looks like curve commonly rises rapidly & contains a definite peak at the top, followed by a decline once the point source is removed, no new cases occur
What is a "continuous (common) epidemic" epidemic curve? What does the curve look like on the graph?Exposure to the source is prolonged over an extended period of time & may occur over > 1 incubation period. On the graph, the down slope of the curve may be very sharp if the common source is removed or gradual if the outbreak is allowed to exhaust itself
What is a "propagating epidemic" epidemic curve? What does the curve look like on the graph?Occurs when dz is introduced through a single (primary) source of infxn in 1 animal & then xmitted to other animals. The graph has multiple peaks & regressions
What is the frequency of an endemic like?Dz occurs at expected frequency
What is the frequency of an epidemic like?Dz occurs at greater than expected frequency
What is the frequency of "sporadic dz" occurrence like? What is distinct about them?Only a small number of cases are observed during a short period of time, dz occurs rarely & w/o regularity & there are no 2° cases
Look at slide 24 for sporadic vs endemic vs epidemicEpi & sporadic look similar, except sporadic is much fewer cases
What does a time series analysis do?Uses the information on patterns of dz occurrence obtained from temporal occurrence data...the temporal occurrence data will identify periods of high/low risk (trends) of dz occurrence → allows casual associations to be explored
What are the 3 trends of time-series analysis?Short-term
Cyclical (including seasonal)
Secular trends
What is a secular trend?A long term trend, where the data reflects an overall ↑ or ↓ in incidence occurring gradually over long time periods
What is a cyclical trend like?Rise & fall of Dz over greater than 1 year Associated w/ regular, periodic fluctuations in level of dz occurrence
What are some factors which would make a cyclical trend a seasonal trend?Things like host density (all migrating together or something)
Management practices
Vector borne Dzs (fly season)
Infectious agent survival due to environmental factors
Dz occurrence can be affected by host factors such as...Age
What is Incidence?A measure of the frequency w/ which new cases occur over a specified time period (other explanations given are:) The proportion of a population, initially free of the outcome of interest that develops the Dz over a given period of time. Incidence refers to NEW cases of Dz
What is prevalence?The number of cases that are present in a given population (other explanations given are:) Proportion of the population at a given time that have the factor of interest
What is attack rate?Measure of the proportion of the population that develops dz at the start of an outbreak among the total exposed
What is the math problem for incidence?I (per 1,000) = the number of new cases in a population during a particular period of time, DIVIDED BY the number of individuals at risk of developing the dz during that period of time. All of this is multiplied by 1000.
How are units of population expressed?Unit of population expressed as whole numbers & in the smallest multiples of 10
What is the math problem for prevalence?# of individuals having a dz at a particular point in time DIVIDED BY # of individuals in the population at risk at that point in time
How is incidence expressed, versus prevalence?Incidence is usually expressed numerically in reference to population at risk (X out of a 1000 or whatever mult of 10)
Prevalence is usually expressed as a proportion btwn 0 & 1, OR a %, OR as a unit of population at risk
What is point prevalence?Number of cases in a population, at a particular point in time.
What does incidence account for that prevalence doesnt?Prevalence, (unlike incidence), does not take into account the duration of dz. It is a snapshot at this point in time.
What is period prevalence?How many people have had the dz during a certain time period, for example over 1 calendar year? It is a combination of point prevalence & incidence
What is the math equation which relates incidence & prevalence?Prevalence = Incidence x Duration of dz
What is a cluster analysis?Geographical information systems used to measure dz occurrence in time & space... This allows us to ID geographical clustering of dz & define as endemic, epidemic, sporadic, pandemic based on time location
What is data modelling used for?Used to test hypotheses & plan health policies
What is a case definition?Set of uniformly applied criteria for a particular dz

Causal relationships

Question Answer
What is Infxn?Ability of the agent to establish itself in a host
What is Pathogenic?Ability of agent to produce dz in host
What is Virulence?Measure of severity of Dz due to agent
Resistance to dz in populations is called...?Herd immunity
The stronger the association btwn a presumed causal factor & dz or outcome, the more likely a cz & effect relationship exists. This is which criteria for establishing a cz?Strength of association
Non-statistical strength of association means?It happened by chance, no real cz or relation
Positive statistical association may indicate...?Causality
A negative statistical association may indicate...?A protective factor
Example/explanation of a causal factor being necessary & sufficient?Certain dose of virus reqd for infxn
Example/explanation of a causal factor being necessary but not sufficient?Occurrence of dz requires 2 or more factors are present
Example/explanation of a causal factor being sufficient but not necessary?Passive smoking can cz feline lymphoma, but other czs of feline lymphoma exist
Example/explanation of a causal factor being neither sufficient nor necessary but can contribute to existing Dz?High fat diet & Cardiovascular Dz
What is Temporal Precedence?The evidence provided demonstrates that your cz happened before your dz occurrence.
Dose-response relationship...what must you remember about this criteria of causal factors?Dz may not develop until exposed to a certain level [ex: exposure/smoke]
"Reversible association" criteria of causal factors means/asks...Does the removal of a factor results in a ↓ or ↑ frequency of dz? (ex: Cessation of smoking leads to reduction of inflammatory & hemostatic markers for cardiovascular Dz)
What is the strongest type of epidemiologic study providing EVIDENCE (NOT PROOF) that an association might be causal? What are the less strong types?A randomized clinical trial is best evidence for causality! Other trials which are not randomized, so are less strong are:
Cohort & case control
Cross sectional
Cases series
Case report
Relative Risk ratios are used in what studies? Odds Ratios are used in what studies? What do they both measure?RR is used in cohort studies. OR is used in case-control studies. They measure the STRENGTH of the association btwn the causal/exposure factor & dz which is a major criteria for judging causal inferences