Epi curves/Determinants of Dz

Question 1

What is the latent period of a dz?

Answer 1

The period when the microbe is replicating but not yet enough for the host to become infectious (ability to spread dz)

Question 2

What is the incubation period of a dz?

Answer 2

The period when the microbe is replicating but the host is not symptomatic yet

Question 3

Can an animal be infectious but not be showing any clinical signs of dz?

Answer 3

YES

Question 4

What is syndromic intervention?

Answer 4

When you target those animals or humans that are symptomatic only

Question 5

What is an infectious dz?

Answer 5

Dz caused by the invasion and multiplication of a living agent in or on the host

Question 6

What is an infestation?

Answer 6

Invasion, but not multiplication of an organism in or on a host (fleas/ticks, some parasites)

Question 7

What does contagious mean?

Answer 7

A contagious dz is transmissible from one human/animal to another via DIRECT or AIRBORNE routes

Question 8

What is meant if a dz is deemed communicable?

Answer 8

It is a dz caused by an agent capable of transmission by DIRECT, AIRBORNE, or INDIRECT routes from an infected person, animal, plant, or a contaminated inanimate reservoir

Question 9

What do epidemic curves represent?

Answer 9

The number of new cases of dz over a period of time

Question 10

What information can you get from an epidemic curve?

Answer 10

Most probable source of the outbreak
if the pathogen is contagious
if the outbreak is ending - or will continue
incubation period of the pathogen (sometimes)
Info about outliers

Question 11

What are some interpretations of or information that can be concluded from early outliers on an epi curve?

Answer 11

Could be a person/animal that gets the dz way earlier than the outbreak
Could be patient zero
Can potentially help identify the source of infection

Question 12

What information can you get from a late outlier on an epi curve?

Answer 12

It could be an unrelated incident
Could be a secondary case
Could be much later exposure
or could be an extra long incubation period

Question 13

What kind of disease would make an epi map with a propagated curve?

Answer 13

Contagious disease

*exposure followed by “waves” of secondary and tertiary cases

Question 14

What information can be taken from an epi curve that follows the Common source single point exposure pattern?

Answer 14

All animals are exposed at once to the same source of infection

Not a contagious agent - this outbreak can fizzle out on its own

Can determine the minimum, average, and max
**if you are working with a dz that has a known incubation period - you can calculate the day of exposure

Question 15

Looking at an epi curve that displays ‘common source with intermittent exposure’ pattern, is that dz likely to continue spreading or fizzle out on its own?

Answer 15

It is likely to continue - need intervention to stop it

The incubation period on this curve is not clearly shown.
*animals are exposed at different times, but to the same source

Question 16

What are some factors that help shape an epi curve?

Answer 16

Host - immunity or resistance to dz. Direct transmission

Agent: infectiousness of agent, latent and incubation periods, duration of infectivity

Environment

Question 17

What is the difference between endemic/enzootic and epidemic/epizootic?

Answer 17

Endemic - a situation which all factors influencing dz are relatively stable, resulting in little fluctuation in dz incidence other time

Epidemic - is an increase in numbers of expected cases (like an outbreak)

Question 18

What are negative determinants?

Answer 18

Risk factors for dz

Question 19

T/F: Determinants are randomly distributed

Answer 19

FALSE

Some populations have higher determinants than others (increasing their risk/chance of dz)

Question 20

Factors that determine the probability, distribution, or severity of a disease in an animal or population of animals are referred to as ___________

Answer 20

Determinants

Question 21

What are some examples of physical environment determinants?

Answer 21

Water source, temperature/climate, food source, surrounding animals

Question 22

Why are determinants important to know?

Answer 22

So you can identify animals at particular risk (most commonly young, and old animals)
to better practice disease prevention (Ex: knowing who to vaccinate, and what to vaccinate for in specific locations)
Aid to differential diagnosis

Question 23

What is a primary determinant?

Answer 23

A MAJOR contributing factor, usually a necessary one

Question 24

What is a secondary determinant?

Answer 24

Factors that make disease more or less likely; predisposing or enabling factors

Question 25

What is the different between intrinsic and extrinsic determinants?

Answer 25

Intrinsic = determinants that are internal to the animal (age, breed, sex, etc)

Extrinsic = determinants that are external to the animal (housing, medical treatment etc)

Question 26

Which determinants are easier to modify, intrinsic or extrinsic?

Answer 26

Extrinsic

Question 27

T/F: Primary determinants must ALWAYS be there in order for disease to occur

Answer 27

TRUE

Question 28

What are two characteristics of infectious agents that make them harder to treat or diagnose?

Answer 28

Mutation rate and resistance

Question 29

What are some mutations or results of mutations of infectious agents?

Answer 29

Increased infectivity within typical hosts
Ability to infect new species or host populations
Acquisition of new toxins
Immune system evasion

Question 30

In what ways can antibiotic resistance be obtained?

Answer 30

de novo, through mutation, or via lateral transfer from another organism

Question 31

Genetic diseases are entirely determined by genotype. This makes them _________ determinant of dz

Answer 31

Primary

Question 32

Genetic susceptibilities are partially determined by genotype and partially determined by other factors. When determined by “other factors” you are referring to ________ determinants.

Answer 32

Secondary

Question 33

Is diet considered an intrinsic or extrinsic factor?

Answer 33

Extrinsic - more of a management issue

But the body condition score of an animal and nutritional status are intrinsic

Question 34

T/F: Giving a vaccine is an example of an intrinsic preventative treatment

Answer 34

False - this is extrinsic

The status of the body being immune, however, is intrinsic

Question 35

What is herd immunity?

Answer 35

The idea that infectious diseases can be contained if the population’s resistance to infection is high enough

(usually 80% or more herd immunity is required to provide safety for others)