Class 3-7: Descriptive Epi. Flashcards
This can be used to know if a location is experiencing disease occurrence more frequently than usual or more than other locations
Descriptive epidemiology
Frequencies
Counts in relation to size of population
Patterns of disease
Encompass 3 aspects: person, place, and time
[who,where,when]-descriptive epidemiology
Passive surveillance system
Relies on healthcare system to follow regulations on required reportable diseases-healthcare officials wait for reports to come in
Active surveillance system
Public health officials go into communities to search for new diseases/conditions
Syndromic surveillance system
A system that looks for pre-defined signs/symptoms of patients r/t trackable-but-rare diseases
Biosurveillance
Taking samples of human, plant, animal, environment )
Induction period
Time between exposure and onset of disease
Latency Period
Time between onset of disease and disease detection
The most CRITICAL element that must be defined/determined before any of the WHO-descriptive epidemiology can be accomplished?
The “case”-constant definition of disease that can be studied
“Case”
A set of uniform criteria I used to define a disease for public health surveillance
What is the list of reportable diseases called?
National Notifiable Disease Surveillance System (NNDSS)
Who writes the list of reportable disease?
Council of state and territorial epidemiologists (CSTE)
How often are reportable lists updated
Annually
Two types of Case definitions
Confirmed and probable (lethal-need to notice fast)
3 elements of descriptive epidemiology
- Who
- When
- where
Epidemic
Occurrence of disease clearly in excess of normal in a community/period clearly defined
Outbreak
Also called “cluster” An epidemic limited to a localized increase in the occurrence of disease
Distinction between outbreak and epidemic
Outbreaks[clusters] would become epidemics if they continue to rise above an average (usually an annual average)
Endemic
The CONSTANT presence of a disease w/in a given area or population in excess of normal levels in other areas
Emergency of International concern
An epidemic that alerts the world to the need for high vigilance (pre-pandemic labeling)
Pandemic
An epidemic spread world-wide (global health)
What is the epidemic curve?
A visual time-based depiction created during an outbreak/epidemic of the # of cases by date reporting
Common source or point source
Continuous OR intermittent;
Not person-to-person spread, derived from a common, single point source for the outbreak
Propagated Source
Person to person spread; appear as sawtooth curve
Sentinel case
Starting case
How do epidemic curves help?
Help to form hypothesis; routes transmission,exposure period, incubation period
How to measure disease frequency?
Ratios, proportions, rates
Ratios
Division of 2 unrelated number
Proportions
Simple %; part / whole,
Division of 2 RELATED numbers
Rates
A proportion(%) w/ time incorporated into the denominator
3 factors comparing measures of disease frequency between groups:
1 frequency of affected- #of ppl
2 Size of population
3 Length of time reported
[FST]
Comparing frequencies requires 3 things:
The frequency, population size, and time period
[FST]
Incidence
New cases of disease
Prevalence
Existing cases of disease + new cases of disease
Dynamic populations
Fluctuating population
How to calculate repeat cases of disease?
Only count first occurrence b/c it gets too complicated and can make a different rate w/ repeat cases
How to calculate incidence rate for dynamic populations?
Incidence density
Point prevalence
Prevalence at a given point in time
Period prevalence
Prevalence over a given period of time
Crude morbidity rate
ppl w/ disease / # ppl in population
Crude mortality rate
ppl died / # ppl in population
Cause-specific morbidity rate
ppl w/ cause-specific disease / # ppl in population
Cause-specific mortality rate
ppl w/ cause-specific death / # ppl in population
Case-fatality rate
cause-specific deaths / # of cases of disease
Cause-specific survival rate
cause-specific cases alive / # of cases of disease
Proportional mortality Rate (PMR)
cause-specific deaths / total # deaths in population
What is the same for case-fatality rate, cause-specific mortality rate, and proportional mortality rate?
The nunmerator: # cause-specific deaths
Difference in case-fatality rate, cause-specific mortality rate, and proportional mortality rate?
Denominator
Case-fatality rate: everyone w/ disease
Cause-specific mortality rate: everyone in population
Proportional Mortality rate: ALL deaths
Live birth rate
births/ 1,000 population
Fertility rate
births/ 1,000 women of childbearing age
Neonatal mortality rate
deaths
Postnatal mortality rate
deaths in greater than or equal to 28 days but
Infant mortality rate
deaths
Maternal mortality ratio
female deaths r/t preg / 100,000 births
Infectivity
Ability to invade a patient [host]
Pathogenicity
Ability to cause clinical disease
Virulence
The ability to cause death (synonymous w/ case-fatality rate)
