BIOL 437 Week Four Part 2 Flashcards
epidemic curve
- histogram
- shape can suggest hypothesis
- incubation period
incubation period
-time between exposure and onset of symptoms
common source types
- point: same exposure over limited time period
- intermittent
- continuous
propagated (simple)
-spread from person to person
mixed epidemics (simple)
-a mixture of common source and propagated
common source
-tend to result in more cases occuring more rapidly
>sooner than host-to-host epidemics
-removing exposure to common source typically causes the epidemic to rapidly decrease
examples of common source
- anthrax: milk or meat from infected animals
- botulism: traced to soil-contaminated foods
propagated
- arise from infections being transmitted from one infected person to another
- indirect or direct transmission
- host-to-host epidemics rise and fall more slowly than common source
examples of propagated
- tuberculosis
- whooping cough
- influenza
- measels
- covid-19
mixed epidemics
- occurs when a common source is followed by person-to-person contact
- disease is spread as a propagated outbreak
ex. shigellosis
time-series analyses
-ecologic: group level
-longitudinal data: individual level
>age effect
>cohort effect
>period effect
time-series design
- searching for patterns of disease over time
- secular trend/temporal variation
- cyclic patterns
cyclic patterns
-recurrent alterations in the occurence, interval or frequency of diseases
>seasonality
-periodic increases and decreases in occurence
types of trends
- secular
- short term
- cyclic patterns/trends
secular trends
-represent long-term changes in health-related states or events