Quiz 1 Flashcards
Define
What is epidemiology?
Lecture 1
the study of the distribution and determinants of health-related states or events among specific populations and the application of the study to the control of health problems
Epidemiology: True or False
Epidemiology is often described as the basic science of public health.
True
Epidemiology
What is distribution?
Lecture 1
frequency + pattern
- in other words: “how many people?” + “where?”
Epidemiology: Distribution
Define frequency
Lecture 1
- the number of health-related events
- how often these events occur compared to the total number of people in the population
Epidemiology: Distribution
Define pattern
Lecture 1
- occurrence of health-related events by time, place, and person
- time may be: annual, seasonal, weekly, daily, hourly, weekday vs weekend, etc.
- place includes: geographic variation, urban/rural differences, location of work sites or schools
- personal characteristics include: age, sex, marital status, SES, behaviors, and environmental exposures
Epidemiology
What are determinants?
Lecture 1
the causes and other factors that influence the occurrence of disease and other health-related events
Specified Populations
Epidemiologist vs. Physicians
Lecture 1
Epidemiologist:
- concerned about the health of the overall population
Physicians:
- concerned about the health of an individual
clinician’s patient is indiviual; epidemiologist’s patient is community
Epidemiology
What is the application of epidemiology?
Lecture 1
it involves applying the knowledge gained by the studies to community-based practice b/c the goal is to prevent disease in the community
John Snow
Who is John Snow?
Lecture 2
An anesthesiologist in the mid 1800s who conducted a series of investigations in London.
- conducted studies of cholera outbreak to discover the cause of disease and how to prevent its recurrence
John Snow: True or False
The father of epidemiology is John Graunt.
Lecture 2
False
John Snow
Breakdown and explain Snow’s first investigation
Broad Sreet Pump
Lecture 2
- A severe cholera epidemic occurred / outbreak
- Snow created a spot map, marking where cholera cases occurred and the locations of water pumps
- He observed patterns and notices most cases clustered around the Broad Street pump (Pump A)
- Then, he gathered community insights and found out that residents avoided Pump B because it was contaminated and Pump C because it was inconvenient
- To confirm his findings, he investigated anomalies and found that workers at a nearby brewery who drank from a private well did not get cholera and gathered infromation on where people with cholera obtained their water
- Snow formed his hypothesis and conclued that contaminated water from the Broad Street pump was likely the source of the outbreak
- Lastly, he took action by presenting his information to officials and got the pump handle removed
Epidemiology - John Snow
What is descriptive epidemiology?
Lecture 2
describing a health related event in terms of person, place, and time
Epidemiology - John Snow
What is analytic epidemiology?
Lecture 2
measures the association between an exposure and disease
John Snow
What does Snow’s research demonstrate
Lecture 2
- descriptive epidemiology
- hypothesis generation
- hypothesis testing / analytical epidemiology
- application
Epidemiology: Uses
What are the 4 diff uses of epidemiology?
Lecture 2
- Assessing the community’s health
- Making individual decisions
- Completing the clinical picture
- Searching for causes
Epidemiology: Uses
Assessing the community’s health
Explain
Lecture 2
use of data to set goals and monitor progress towards them
- need relevant sources of data
ex: Healthy People 2030
Epidemiology: Uses
Making individual decisions
Explain
Lecture 2
use of epidemiologic information to make daily decisions about health
Epidemiology: Uses
Completing the clinical picture
Explain
Lecture 2
epidemiologists assist physicians in properly diagnosing illness
Epidemiology: Uses
Searching for causes
Explain
Lecture 2
provides substantial evidence to link exposure and illness and effect action
in other words: why did this disease happen
Epidemiology: Core Functions
What are the 6 core functions of epidemiology?
Explain
Lecture 2
- public health surveillance
- field investigations
- analytic studies
- evaluation
- linkages
- policy development
Epidemiology: Core Functions
Public health surveillance
Explain
Lecture 2
ongoing, systemic collection of data to guide decision making and action
goal: to portray patterns of disease to control spread and implement prevention measures
how: morbidity and mortality reports
Public Health Surveillance
What is the difference between active and passive surveillance?
- active: surveillance is on public officials
- passive: other entities report the data
Epidemiology: Core Functions
Field Investigation
Explain
Lecture 2
the process of collecting and analyzing data directly in affected areas to find the source and spread of a disease
also referred to as “shoe leather epidemiology”
Epidemiology: Core Functions
Analytic studies
Explain
Lecture 2
evaluate the credibility of a hypothesis generated from surveillance and field invetigation
Epidemiology: Core Functions
Evaluation
Explain
Lecture 2
determmine relevance, effectiveness, efficiency, and impact in relation to goals
Epidemiology: Core Functions
Linkages
Explain
Lecture 2
connecting public health agencies, laboratories, and healthcare providers to share information and collaborate on disease prevention and response, etc.
Epidemiology: Core Functions
Policy Development
Explain
Lecture 2
creating and implementing public health policies based on data and research to protect and improve community health
Epidemiologic Approach
What does an epidemiologist do?
Lecture 3
- Counts cases or health events, and describes them in terms of time, place, and person
- Divides the number of cases by an appropiate denominator to calculate rates
- Compares these rates over time or for different groups of people
Epidemiologic Approach
Define rate
Lecture 3
the number of cases divided by the size of the population per unit of time
Case definition
What is a case definition?
Lecture 3
a set of standard criteria for classifying whether a person has a particular disease, syndrome or other health condition
Case definition
What are the components of a case defintion?
Lecture 3
- lab tests
- signs (objective)
- symptoms
- time, place, and/or person (outbreak investigations)
True or False
Case definitions are set and do not change.
Lecture 3
False
case definitions may change over time as more information is obtained
Case definition
What are the different types of case definitions?
Lecture 3
sensitive: broad or loose
goal = to capture all true cases
strict: specific
goal = ensure an individual is truly a case
True or False
ALL case definitions require laboratory confirmation
Lecture 3
False
some disease have no distinctive laboratory findings
Epidemiology
What are the 5 W’s of epidemiology?
Lecture 3
- what (health issue of concern)
- who (person)
- where (place)
- when (time)
- why/how (why is this disease occurring and how is it spreading)
Epidemiology
What are the different ways to compile data by time?
Lecture 3
- secular trends (overtime/long term)
- seasonally
- days of the week/time of the day
- epidemic period
Epidemiology
What are the different ways to compile data by geographic extent?
Lecture 3
unit:
- large (continent)
- small (hospital wing)
categorical:
- urban
- rural
state
Epidemiology
What is used to compile data when it comes to people?
Lecture 3
- sex
- ethnicity
- SES
- age
- occupation
- leisure activity
- behaviors
- use of medication
Epidemiology
What is the most important person attribute when compiling data according to the textbook?
Lecture 3
age
Analytic Epidemiology
What is the key feature of analytic epidemiology?
Lecture 3
comparison group
Analytic Epidemiology
What are the two categories of studies that fall under analytic epidemiology?
Lecture 3
- experimental
- observational
Analytic Epidemiology
What are the functions of an experimental study?
Lecture 3
- controlled process determines the exposure for participants
- tracking over time determines the effects of the exposure
ex: placebo
Analytic Epidemiology
What is the function of observational studies?
Lecture 3
to observe the exposure or disease status in participants
Analytic Epidemiology: Observational Studies
What are the 3 types of observational studies?
Lecture 3
- cohort (prospective)
- case control
- cross sectional
Analytic Epidemiology
What are the features of a cohort study?
Lecture 3
- start with exposed individuals (we know the exposure)
- follow individual to see if they develop disease of interest
Analytic Epidemiology
What are the features of a case-control study?
Lecture 3
- investigators enroll a group of participants with a disease (case-patients)
- starts with ill individuals (we are looking for the exposure)
- control group provides an estimate of the baseline or expected amount of exposure in the population
Analytic Epidemiology
What are the features of a cross-sectional study?
Lecture 3
- weakest study because it lacks time aspect but gets a quick idea
- exposures and health statuses of sample population are measured simultaneously
- assesses the prevelance of a health outcome at that point in time without regard to duration
- exposure and outcome are measured at the same time
Analytic Epidemiology
Overall summary
lecture 3
cohort: starts with exposed individuals
case control: starts with ill individuals (back tracking and seeing what exposure led to them being sick)
cross section: measures exposure and disease at the same time
Models of Disease Causation
What are the 3 models of disease causation discussed?
lecture 4
- Rothman’s Pie
- Chain of Infection
- Epidemiologic Triad/Triangle (simplest)
Models of Disease Causation
What does the Epidemiologic Triad consist of?
lecture 4
agent, host, environment
Concepts of Disease Occurrence
Agent
lecture 4
infectious microorganism or pathogen
- virus, bacterium, parasite, or other microbe
- chemical contaminants or physical causes of disease or injury
generally: agent must be present for disease to occur
Concepts of Disease Occurrence
Host
lecture 4
the human who can get the diease
- dependent upon susceptibility, response to an agent
Concepts of Disease Occurrence
Environment
lecture 4
extrinsic factors that affect the agent and the opportunity for exposure
- geology
- climate
- insects transmitting the agent
- socioeconmic factors
Models of Disease Causation
Rothman’s Pie
lecture 4
all pieces of the pie fall into place = disease occurs
- component causes: individual factors (one piece)
- sufficient causes: complete pie (if more pieces come together
- necessary causes: component that occurs in every disease pie (most usually its the bacteria)
Concepts of Disease Occurrence
Natural history
define
lecture 4
the progression of disease in an individual over time in the absence of treatment
timeline could be years
Concepts of Disease Occurrence
Spectrum of disease
define
lecture 4
the range of manifestations and severities of illness associated with given dieases, illness or injury
Infectious Agents
What are the terms for infectious agents?
lecture 4
infectivity: proportion of exposed persons who become infected
pathogenicity: proportion of infected individuals who develop clincally apparent disease
virulence: the proportion of clinically apparent cases that are severe or fatal
Natural History Timeline
What is the timeline for disease?
lecture 4
- stage of susceptibility (exposure occurs)
-
stage of subclinical disease (where pathologic changes occur but individual does not know they are sick; asymptomatic)
in between: onset of symptoms and usual time of diagnosis - stage of clinical disease (symptoms present and individual knows they are sick)
- stage of recovery, disability or death
infectious disease: incubation period
chronic disease: latency period
Chain of infection
What is the chain of transmission?
lecture 4
transmission occurs when the agent leaves its reservoir or host through a portal of exit, is conveyed by some mode of transmission and enters through a portal of entry to infect a susceptible host
Portal of Exit
What is portal of exit?
lecture 4
how the pathogen leaves its host
corresponds to the site where the pathogen is localized
Modes of Transmission
What are the two modes of transmission?
define
lecture 4
direct:
- direct contact (mono)
- droplet spread (sneezing, coughing, etc.)
indirect:
- airbone (infectious agents carried by dust or droplet nuclei suspended in the air; ex: measles)
- vehicle (food, water, biologic products)
- vector (mosquitoes, fleas, ticks, etc.)
Modes of Transmission
Define airbone
lecture 4
infectious agents carried by dust or droplet nuclei suspended in the air
Modes of Transmission
Define vehicle
lecture 4
food, water, biologic products (blood), etc
Modes of Transmission
Define vector
lecture 4
mosquitoes, fleas, ticks, etc.
Portal of Entry
What is portal of entry?
lecture 4
how a pathogen enters a susceptible host
ex: skin, mucous membrane, blood
How does the host susceptibility vary?
lecture 4
- genetics differ
- immune/resistant to disease
- lifestyle factors
etc.
Implications for Public Health
What are interventions directed at?
lecture 4
- controlling or eliminating agent
- interrupting the mode of transmission
- protecting portals of entry
- increasing a host’s defenses
Level of Disease
What levels of disease are there?
lecture 4
- sporadic
- endemic
- hyperendemic
- epidemic
- outbreak
- cluster
- pandemic
Level of Disease
Define sporadic
Lecture 4
disease that occurs infrequency/irregularly
- uncommon
- random
- one case/first case
Level of Disease
Define endemic
Lecture 4
amount of disease usually present in a community
- typical cold or flu
- we expect this, its our usual
Level of Disease
Define hyperendemic
Lecture 4
persistent, high levels of disease
- regularly
Level of Disease
Define epidemic
Lecture 4
often sudden increase of cases
Level of Disease
Define outbreak
Lecture 4
often sudden increase of cases in a more limited geographic location
- ex: on stony brook campus vs in state of NY
Level of Disease
Define cluster
Lecture 4
aggregation of cases grouped in place and time suspected to be greated than the number expected
- don’t know why
- unrelated
Level of Disease
Define pandemic
Lecture 4
epidemic spread over several countries or continents
Levels of Disease - Epidemic
Why do epidemics occur?
lecture 4
- agent and host present inadequate numbers
- increase in amount of virulence of agent
- introduction of agent in a setting it has never been before
- enhanced mode of transmission
- change in susceptibility of hosts
- new portals of entry
Epidemic Patterns
What are the type of patterns used to classify epidemics?
classified according to their manner of spread through a population
lecture 4
- common source
- propagated
- mixed
Epidemic Patterns
Define common source
lecture 4
group of persons are all exposed to an infectious agent or a toxin from the same source
point source: group exposed over a relatively brief period (becoming sick in the same incubation period)
continous common source: case-patients exposed over days, weeks, or longer
intermittent common source: irregular pattern of exposure (still from the same source)
Epidemic Patterns
Define propagated
lecture 4
transmission from one person to another; cases occur over more than one incubation period
- direct person-to-person
- vehicle or vectorborne
