Flashcards in Epi Class 10 Deck (22):
Modes of Transmission
Direct (person-to-person) transmission
- Contact with blood or body fluids
- Sexual contact
- IDU (injecting drug use)
- Fecal-oral spread
Where in the ‘environment’ is the infection found?
- Humans (anthroponosis)
- Animals (zoonosis)
Cycle of Infection: examples
Human – human – human
Vertebrate – vertebrate – human
Insect - human – insect – human
agent reproduces inside a person
# infected / # exposed (and susceptible at time of exposure)
Do all exposure cause infection/disease?
Not all exposures cause an infection
Not all infections cause disease (symptoms)
# ill (symptomatic = diseased) / # infected
# with severe illness or death / # with symptoms
High virulence will be associated with a high case fatality rate
short-term (measure with incidence)
long-term (measure with prevalence)
more cases than normal
ongoing tracking through disease reports to catch outbreaks early
limit infection within an area
no new cases of the infection in the area
no new cases anywhere in the world
not even stored samples in some refrigerator!
1. What is the case definition? (How will you know if someone has the disease of interest?)
2. Descriptive Epidemiology Triad:
- Person: Who participated in the study or event?
- Place: WHERE did the study or event occur?
- Time: WHEN did the study or event occur?
3. Analytic Epidemiology Triad: Agent – Host – Environment (AHE)
- WHY did the disease outcome occur in certain people or certain population groups?
Epidemic Curve: Point Source
One time exposure. Incidence dramatically peak at one point in time
Epidemic Curve: Continuous Source
Constant exposure. Incidence remains relatively consistent over time