Epidemiology Exam 1

define epidemiology

the science, or the collection of methods, used to explain the distribution and determination of health-related outcomes in populations

what are the components of the epidemiology triad?

• sick animal

• agent

• host

• environment

what is the purpose of epidemiology?

• determine the magnitude of disease in populations

• study the natural history and prognosis related to disease

• identify causes and predictors of health outcomes

• evaluate preventive and therapeutic factors

• collect quantitative data as the foundation for public policy

define incubation period

the interval from effective exposure to an infectious agent and the onset of related disease

define induction period

the interval from effective exposure to a non-infectious agent and the onset of related disease

define pre-patent period

the interval from effective exposure to the infectious agent and the detection of the agent in the tissues or secretion of the host

define pathogenicity

the ability of an agent to produce clinical disease

define virulence

the ability of an agent to produce severe disease

define infectivity

the ability of an agent to enter, survive, and multiply in the host

define infectious

the ability to transmit infection (indirectly or directly)

define contagious

the ability to transmit infection through direct contact

define latent infection

persistence of an infectious agent within the host without active replication/ shedding

pre-patent period is a type of

latent infection

define carrier state

persistence of an infectious agent within the host without clinical signs or symptoms with active replication and shedding or with the potential to replicate and shed in the future

define reservoir

the biological niche that supports the infectious agent under natural conditions before “escaping” into the animal or human population of interest

define source

the actual object (substance, animal, person) from which the infection is acquired

define vehicle

an inanimate substance that serves to pass an infectious agent to susceptible individuals

define fomite

inanimate object that is capable of transmitting an infectious agent

define vector

animate object that is capable of spreading infection

cases that occur irregularly without a discernable pattern can be described as

sporadic

cases the occur regularly with a perdictable pattern can be described as

endemic

cases that occur clustered in time and space can be described as

epidemic

define pandemic

an epidemic affecting many countries in the world

what are the important characteristics to include when describing an epidemiological situation?

• animal: what are the characteristics of those affected

• place: where were the individuals when they became affected

• time: when did the individuals become affected

define outbreak

a sudden rise in the incidence of disease but is often used for limited geographical distributions

define cluster

an aggregation of cases in place and time that are believed to be greater than expected

define point source

all animals exposed within a short period of time

define line source

point source but with extended time of exposure

what are the stages of the epidemic curve?

1. endemic level

2. ascending part of the curve

3. plateau

4. descending branch

5. secondary peak

what is the cause of the secondary peak?

introduction of new susceptible animals or secondary transmission