search for additional cases and clues regarding source & mode of transmission
shoe leather epidemiology
measures exposure & early biological response by 1) evaluating host characteristics 2) using biochemical markers of a positive effect to refine disease categories
molecular epidemiology
Establishes 1) a genetic part to disorder 2) relative size of that genetic effect in relation to other sources of variation in disease risk & 3) responsible genes
genetic epidemiology
Pathogen must be present in case of disease
Pathogen can be isolated from infected host & grown in pure culture
Pathogen must cause disease when injected into new susceptible host
Pathogen reisolated from new host must be same as og inoculated pathogen
kochs postulates
Single pathogen can cause multiple disease
vice versa of 1 (one disease can be caused by multiple pathogens)
Some pathogen only cause disease in human and can’t be cultured in a lab
exceptions of kochs postulates
entire pop affected
holoendemic
persistent, high level disease
hyperendemic
disease constantly at low incidence = little or no immunity
hypoendemic
disease caused by doctor or meds
iatrogenic
disease w unknown cause
idiopathic
denominator of person time rate
# of people followed multiplied by # of years
indirect measurement
proxy measurement
microbes that usually do not cause disease in healthy people, but may become virulent with immunocompromised and unhealthy individuals
opportunistic pathogen
LD50
Lethal Dose. dose that causes the death of 50% of a group of test animals
MRSA stands for
Methicillin Resistant Staphylococcus
MMWR
Morbidity mortality weekly report
When was WHO founded? (Month day, year)
April 7, 1948
What is a serial interval?
Duration between onset of secondary case from primary case
What is the chain of transmission triad?
Agent, vector, host
Pros of public health surveillance (3)
Timeliness, simplicity, felxibility
Cons of public health surveillance (3)
Expensive, not reproducible
What are the 5 steps of good surveillance?
Data collection, analysis, interpretation, dissemination, action
What are the pros of passive surveillance? (3)
Cheap, good for monitoring trends over time, large-scale
What are the cons of passive surveillance? (3)
Underreporting, low sensitivity, not representative
What are the pros of active surveillance? (3)
More information, better quality, high sensitivity
What are the cons of active surveillance? (3)
High use of resources, time consuming, hard to sustain over time
What are the pros of sentinel surveillance? (3)
High-quality, fast, cheap
What are the cons of sentinel surveillance? (3)
Bad for rare diseases, won’t report stuff outside sites, bad in monitoring incidence over time
What are the pros of syndromic surveillance? (3)
Low bias, cheap, fast
What are the cons of syndromic surveillance? (3)
Low specificity, bad for big outbreaks, inaccurate
What are the 13 steps of an outbreak investigation?
Prepare for field work, establish existence of disease, verify diagnosis, form case definition, find cases systematically and record info, use descriptive epidemiology, find hypothesis, evaluate hypotheiss, reconsider, refine, re-evaluate hypothesis, compare and reconcile with lab, control/prevent measures, initiate/maintain surveillance, communicate findings
What are the 9 Bradford hill criteria?
Strength of association, consistency, specificity, alternative explanation/casuality, temporality, dose-response/biological gradient, biological plausibility, experimental evidence, coherence
Single cause cause specific effect means what?
Specificity
What does it mean to consider multiply hypothesis before saying association causal or not?
Alternative explanation/causality
What does cause/exposure must precede outcome mean?
Temporality
What does it mean to have a stronger response when there’s more exposure?
Dose-response
What does it mean to be able to alter the condition or prevent/accelerate it?
Experimental evidence
What does it mean when the association is compatible with existing theory and knowledge of past cases?
Coherence
What case compares patients to themselves?
Case-crossover
What study is risk factors known, disease not known?
Cohort
What study is disease known, risk factors not known?
Case-control
What do you use for cohort studies?
Risk ratio
What do you use to calculate case-control studies?
Odds ratio
What are the pros for cohort? (3)
Good for long term disease, good for rare exposure, assess multiple outcomes for 1 exposure
What are the cons for cohort? (3)
Bias, costly, need large population
What are the pros for case-control? (3)
Cheap, good for rare & long latency period disease, shorter
What are the cons for case-control? (3)
Unreliable information, confounding variable, can’t calculate prevalence
What do you use to calculate cross-sectional?
Prevalence
What are the pros of cross-sectional? (3)
Quick, cheap, easy
What are the cons of cross-sectional? (3)
Low response, no causality, recall bias
Selection bias, patients lost to follow up exluded
Attrition bias
Selecting people from subpop
Berkson’s (selection) bias
Bias toward belief we already have
Confirmation bias
How can confounding be prevented?
Randomization, restriction, matching
When correlation at group level doesn’t accurately represent correlation at the individual level
Ecological fallacy
When people in survey don’t include dead/ill
Late look bias
Systematic difference between reported & unreported
Reporting bias
Groups differ in ways other than exposure
Selection bias
People with severe illnesses can’t fill out survey & excluded from study
Neyman bias
Out of how many people who have the disease, how many people actually test positive?
Sensitivity
Out of all the people who do not have the disease, how many people actually test negative?
Specificity
Out of all the people who test positive, how many people actually have the disease?
PPV
Out of all the people who test negative, how many people actually don’t have the disease?
NPV
Father of modern surgery
Joseph Lister
Created polio vaccine
James Salk
Landmark analysis of mortality data
John Graunt
Made smallpox vaccine
Edward Jenner
Father of epidemiology
John Snow
Made anthrax vaccine
Louis Pasteur
Primary control example (3)
Public education, vaccine, ban products
Primordial control example (3)
Optimal diet, remove barriers to exercise, government tax on cigarettes
Secondary control example (3)
Screening, physical exam, colonoscopy
Tertiary control example (3)
Rehab, surgery, speech therapy
Quaternary control example (3)
Pull plug on patient, anti arrhythmic drug, hormone replacement therapy
Public policy to restrict spread of agent before people begin to protect against agent
Control
Reduction to 0 of incidence of infection caused by specific agent in geographical area
Elimination
Permanent reduction to 0 of worldwide incidence of infection
Eradication
Agent does not exist in nature or in lab
Extinction
What graph is this and what spread is this?
Common continuous, water borne
What graph is this and what spread is this?
Point source, foodborne
What graph is this and what spread is this?
Propagated, person-perosn
What graph is this and what spread is this?
Intermittent, sporadic
What is leading rabies vector
Bats
Why cooked food still cause harm? 3
Temperature not hot enough, toxin is heat stable, release endotoxin from dead agent
Science of causes and effects of disease
Pathology
Study of cause of disease
Etiology
Biochemical test that measures presence/concentration of macromolecule in solution through proteins/antigens
Immunoassay
A study design in which the investigator specifies the type of exposure for each study participant
Experimental
A study in which a sample of persons from a pop are enrolled and their exposures and health outcomes measured simultaneously
Cross-sectional
What study is least subject to recall bias
Prospective cohort study
Want to test a hypothesis but don’t have funding or time. Have national data on masking policies and number of students in each district. What study design do you use?
Ecological
T/F One can skip the preparing for field work step of outbreak investigation unless one is traveling.
F
You have unlimited budget and access to labs but little time.
Case control
what case
Case control
some people may be infected with SARS/CO-V and have a negative test. What source of error (bias) is this?
Misclassification bias
Vector in which the parasite multiplies in numbers/undergoes developmental change in life cycle
Biologic vector