Epi Curves and Determinants of Disease

Question 1

What is a latent period?

Answer 1

Microbes are replicating, but not yet enough for the host to be INFECTIOUS.

Question 2

What is the incubation period?

Answer 2

Microbes are replicating, but not yet SYMPTOMATIC. NOTE: Doesn’t always correlate with the latent period.

Question 3

Define infection.

Answer 3

Invasion and multiplication in/on a host.

Question 4

Define infestation.

Answer 4

Invasion, but NOT multiplication in/on a host.

Question 5

Define contagious.

Answer 5

Disease transmissible via direct or airborne routes.

Question 6

Define communicable.

Answer 6

Disease transmissible by direct, airborne or indirect routes.

Question 7

What do epi curves represent?

Answer 7

The number of new cases of disease over time.

Question 8

What information can an epi curve provide (4 things)?

Answer 8

Most probable source of outbreak If pathogen is contagious If outbreak is ending or not Incubation period Outliers

Question 9

What is the incubation period in this epi curve?

Answer 9

3 days

Question 10

Describe the propagated source pattern.

Answer 10

Exposure followed by waves of cases.

Question 11

What diseases have a propagated source?

Answer 11

Contagious diseases

Question 12

What epi curve pattern is this?

Answer 12

Propagated source.

Question 13

Describe the common source single point exposure pattern.

Answer 13

All animals are exposed at once from the same source, has a bell-curve shape.

Question 14

What diseases show a common source single point exposure pattern?

Answer 14

Non-contagious diseases.

Question 15

What type of incubation time can be determined from a common source single point exposure pattern.

Answer 15

The minimum, average and maximum incubation time can be determined.

Question 16

What epi curve pattern is this?

Answer 16

Common source single point exposure

Question 17

Describe the common source with intermittent exposure curve.

Answer 17

No pattern. Animals are exposed at different times.

Question 18

What type of incubation time can you determine from a common source with intermittent exposure curve?

Answer 18

Incubation period is not clearly shown.

Question 19

What epi curve pattern is this?

Answer 19

Common source with intermittent exposure.

Question 20

What main 3 factors does the epi curve depend on?

Answer 20

Host, agent an environment.

Question 21

What factors fall under the “host” umbrella?

Answer 21

Host immunity or resistance, direct transmission.

Question 22

What factors fall under the “agent” umbrella?

Answer 22

Infectiousness of agent, latent and incubation periods, duration of infectivity.

Question 23

What factors fall under the “environment” umbrella?

Answer 23

Fomites, etc.

Question 24

Describe endemic vs. epidemic.

Answer 24

Endemic is always present at a steady state in a given population, epidemic is a big spike.

Question 25

What is a determinant of disease?

Answer 25

Factors that help determine the probability, distribution or severity in a population.

Question 26

Why are determinants of disease important to know?

Answer 26

Helps identify animals at risk, helps prevent disease, helps with differential diagnoses.

Question 27

What is a primary determinant?

Answer 27

A MAJOR contributing factor, usually necessary.

Question 28

What is a secondary determinant?

Answer 28

Factors that make the disease more or less likely (predisposing or enabling factors).

Question 29

What is an intrinsic determinant?

Answer 29

Factors that are internal to the animal (age, breed, sex).

Question 30

What is an extrinsic determinant?

Answer 30

Factors that are external to the animal (housing, medical treatment, etc.)

Question 31

T/F: Primary determinants must always be present.

Answer 31

True.

Question 32

What are the two agent determinants?

Answer 32

Mutations Resistance

Question 33

What are the 6 environmental determinants?

Answer 33

Demographics Macroclimate Microclimate Housing and crowding Diet Stress

Question 34

What are the 6 host determinants?

Answer 34

Age Sex and behaviour Genotype Breed Nutrition Immunity

Question 35

T/F: Genetic diseases are entirely determined by genotype.

Answer 35

True

Question 36

T/F: Genetic susceptibilities are entirely determined by genotype.

Answer 36

False. Genetic susceptibilities are only partially determined by genotype.

Question 37

T/F: Breeds cannot be used as a visual cue to other, less haritable traits.

Answer 37

False. Breed CAN be used as a visual cue.

Question 38

T/F: Diet is intrinsic, Nutrition is extrinsic.

Answer 38

False. Diet is extrinsic because it's a management issue. Nutrition is intrinsic because it directly pertains to the animal.

Question 39

T/F: Immunity is intrinsic, vaccines are extrinsic.

Answer 39

True.

Question 40

Define "herd immunity".

Answer 40

Infectious disease can be contained if the population's resistance to infection is high enough. Doesn't protect individuals, but many others will be protected indirectly.