Epi MT 1-3 Flashcards
Epidemiology
- define
- Greek breakdown
Study of occurece & distribution of health-related events in specified populations
Epi = upon
Demo = man
Logos = study
“That which befalls man”
Epidemiology
-importance
ID/classify/plan for disease control, causal factor, PHI, allocation of resources
History
- investgated/associated environmental factors with disease (400BC)
- germ theory
- demography - statistical study of pop’s based on vital statistics
Hippocrates
Girolamo Fracastorius
John Graunt
History
- first clinic trial on scurvy
- first modern census - classification of disease leads to ICD codes (int’l classification of diseases)
James Lind
William Farr
History
- in 1800’s studied Cholera
- made what discovery about it
- point of talking about this, according to professor
John Snow
Water-involved spread (contaminated water -> fecal-oral route)
Didn’t know anything about biology of the disease, based entirely on observational data
Disease trends over time
-early vs late 20th century deaths
Early - communicable diseases (pneumonia, flu, TB)
Late - chronic diseases (CV, DM, cancer)
Define endemic
Habitually/chronically present
Define incidence
New cases
Define clinical epidemiology
Application of epidemiology to improve clinical care
Name of the large-scale cohort studies of mid-late 20th century (4)
Framingham
Beaver Dam
Blue Mountiains
Rotterdam
Life expectancy
- from 1900-1950 vs 1950-2004
- since 2015
1900-1950 = huge difference
1950-2004 = little difference
Since 2015 = US life expectancy has declined for first time since 1993
-attributable to multiple causes, but NOT cancer
Epidemiological triad
-3 things & definitions
Host - infected by agent
Agent - factor necessary for disease to occur
(E.g. microorganism, radiation, chemical substance)
Environment - extrinsic factor, affects agent & opportunity for exposure
Direct transmission
- define
- examples
- eye example
Immediate transfer of agent thru portal of entry
Person-person, touching, kissing, mucus membranes (conj), animal bites, trans-placental
Chlamydial trachomatis - adult-inclusion conjunctivitis
Indirect transmission
- define
- examples
Transmitted via vector or vehicle
Vector = animate carrier
-e.g. malaria, lyme
Vehicle = inanimate carrier
-e.g. cholera (water), e coli (food)
Malaria
- worldwide issue
- since 2000
Most deadly vector-borne disease
Significant decrease in incidence and deaths due to vector control (insecticide-treated mosquito nets)
Lyme
- USA issue
- geography
Most common vector-borne disease in USA
Geographical location follows vector distribution
Reservoir
- define
- examples
Habitat the agent dependson for survival and growth
E.g. contact lenses, clothing, utensils
Define epidemic
Occurence of disease in a region in excess of normal expectancy, derived from a common source
(E.g. HIV outbreak in Southern Indiana, syphilis in Florida)
Define outbreak
Same as epidemic, but more localized area
Define pandemic
An epidemic occuring over a wide area (countries or continents)
Define endemic
Habitual presence of a disease within a geographical area
Epidemic classifications
- exposure to a common infectious agent
- sudden/rapid increase in cases, more gradual decrease
- e.g. cholera, *Hep A from food, leukemia after A-bomb
Common source
Epidemic classifications
- transmitted from one person to another
- gradual rise and fall
- can last years/decades
- e.g. flu, measles, TB, AIDS, Hep B
Propagated (host-host)
Epidemic characterizations
-pathogenicity/virulence
—define
—equation
Ability of the agent to cause detectable disease (how “strong” the agent is)
= (# with clinical illness)/(# infected)
Epidemic characterizations
-case-fatality rate
—equation
= (# deaths)/(#infected within a certain period)
Epidemic
-reporting
—CDC program for infectious surveillance system
—if requiring quarantine
NNDSS - national notifiable diseases surveillance system
WHO
Incubation period
- define
- affects
Time bw receipt of infection to illness
Spread of disease
Standard precautions
- formerly
- purpose
- barrier method
- use
Universal precautions
Prevent transmission, esp diseases acquired thru bodily fluid (NOT including tears, sweat)
Gloves, goggles, face shield
All pts, regardless of infectious/symptomatic
Population
- define
- examples
All people in a defined setting or with certain characteristics
Age, sex, race, behaviors (smokers), occupation, etc.
Incidence rate
- equation
- what is measures
= (# of new cases)/(# of total people at risk)
How fast a disease is occuring
Define prevalence
Number of people with a disease (old and new) in a specified population at a specified time
Point prevalence
- equation
- what it describes
= (# of people with a disease)/(total # of people)
A rate - period prevalence is the same, but during a time period
Incidence vs prevalence
I: new cases
P: snapshot of a population at a point of time
-affected by how long someone has the disease - can incr with better tx (DM and insulin) or decr thru death/cure
Morbidity vs mortality
Morbidity: illness or state of having a disease
Mortality: death
Mortality rate
- equation
- usually given per
= (# deaths in population during a specified time)/(# of people in a population during the period)
Per 100k people
Trends
-for death rates 2015-2016, top 10 causes all decreased EXCEPT (3)
Unintentional injuries, Alzheimers, suicide
Crude rates
- equation
- influenced by
= (# of cases)/(# of persons)
Many factors - including age of population
Adjusted rates
- why use
- application examples
Allow for better comparisons in what is measured by removing confounding factors (such as difference in ages of populations)
Glaucoma, cataracts, and heart disease have higher rates in older populations
Crude vs adjusted rates example = if more people are alive/living longer in 2014 than 2000, __ rates will automatically be higher while __ may not be
Crude
Adjusted
- crude rates incr
- when adjusted for age/accounting for the fact that people are living longer, there is actually a slight decr
