Epidemiology of Infectious Disease Flashcards
Definition
the occurrence of diseases in excess of what would normally be expected in a community or geographical area
Epidemic
Definition
a number that represents when the population is completel susceptible. It indicates whether the invasion of the pathogen can give rise to an exponentially growing epidemic
Basic reproductive number (Ro)
How is knowledge of the incubation period used in clinical management?
To predict disease severity, shorter incubation period is associated with severe complications
How are severity of infection and dose related?
The severity of infection may depend on the dose of the pathogen experienced by the host
What is a propagated epidemic?
Driven by person to person
Multiple waves with progressively taller peaks, where each wave roughly corresponds to the infections caused by the wave preceding it
Pathogens evolve (e.g. average viral load) in order to achienve what?
Pathogens evolve (e.g. average viral load) towards a level that balances transmissibility with host survival.
What does the persistence of communicable diseases rely on?
Repleishment of susceptible
- Newborns
- Immigration
- Waning of immunity
Define
Serial interval
the time between symptom onset of successive cases
Define
Herd immunity
a form of immunity that occurs when the vaccination of a significant portion of a population (or herd) provides a measure of protection for individuals who have not developed immunity.
Define
Holoendemic
affecting all or characterized by the infection of essentially all the inhabitants of a particular area
Define
Epidemic
the occurrence of diseases in excess of what would normally be expected in a community or geographical area
What are the possible outcomes of exposure to an infectious agent?
Define
Communicable
a disease that can be transmitted from person to person
Definition
a disease that can be transmitted from person to person
Communicable
Definition
the time between successive infections in a chain of transmissions
Generation time
Definition
the proportion of a given exposed population that has been infected by the pathogen
Attack rate
What can epidemic curves be used for?
Epidemic size
Case distribution
Point-source exposure or propagated epidemic (serial interval)
Identify impacts of events on disease spread
True or False:
Attack rate does not describe how transmissible the pathogen is from person to person
True
What is the prevalence formula (usually)?
Total no. of cases at a specific time period / Population size
Definition
affecting all or characterized by the infection of essentially all the inhabitants of a particular area
Holoendemic
Define
Point-source exposure
Persons are exposed to the same source over a brief time, such as through a single meal or at an event
Definition
the time between symptom onset of successive cases
Serial interval
What happens if the basic reproductive number is greater than 1?
Ro > 1 The pathogen can lead to an exponentially growing epidemic