Definitions

Question 1

What three things make up the epidemiologic triad?

Answer 1

Model of infectious dz causation has three components:

1. an agent
2. a susceptible host
3. an environment (brings 1 and 2 together)

Question 2

What is infectivity?

Answer 2

ability of an infectious agent to cause infection.

Measured as proportion of animals exposed to an infectious agent that become infected

Question 3

Pathogenicity

Answer 3

Ability of an agent to cause disease after infection

Measured as the proportion of animals infected by an agent that then experience clinical disease

Question 4

Virulence

Answer 4

ability of an infectious agent to cause severe disease

Measured as the proportion of animals with the disease that become severely ill or die

Question 5

Incubation period

Answer 5

Time interval from exposure to an infectious agent to the onset of symptoms of an infectious disease

Question 6

Latency period

Answer 6

Time interval from exposure to an infectious agent to the onset of becoming infectious

Question 7

Difference between isolation and quarantine

Answer 7

Isolation is separating known infectious animal

Quarentine is separation of a potentially harmful animal

Question 8

Outbreak

Answer 8

Occurrence of more cases of disease, injury, or other health condition than expected in a given area or among a specific group of animals during a specific period.
Cases have common cause or are related in some way

synonomous to epidemic

Question 9

Endemic

Answer 9

constant presence of an agent or health condition within a given geographic area or population

can also refer to usual prevalence of an agent or condition

Question 10

Epidemic

Answer 10

Occurence of more cases of disease, injury, or other health condition than expected in a given area or among a specific group of animals during a particular period

Question 11

Pandemic

Answer 11

Epidemic occuring over a widespread area (multiple countries or continents) and usually affecting a substantial proportion of the population

Question 12

Outbreak, common source

Answer 12

results from hosts being exposed to the same agent. Exposure period can be brief or can extend over days, weeks, or longer with exposure being either intermittent or continuous

Question 13

Outbreak, point source

Answer 13

common source outbreak in which the exposure period is relatively brief so all cases occur w/in one incubation period

Question 14

Outbreak, propagated

Answer 14

Outbreak that spreads from host to host rather than from a common source

Question 15

Attack rate

Answer 15

Proportion of animals in a population that experience acute health event during a limited period (e.g. during an outbreak)
Calculated as # of new cases of a health problem during an outbreak divided by the size of the population at the beginning of the period