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What is the latent period of a dz?

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


What is the incubation period of a dz?

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


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



What is syndromic intervention?

When you target those animals or humans that are symptomatic only


What is an infectious dz?

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


What is an infestation?

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


What does contagious mean?

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


What is meant if a dz is deemed communicable?

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


What do epidemic curves represent?

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


What information can you get from an epidemic curve?

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


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

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


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

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


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

Contagious disease

*exposure followed by "waves" of secondary and tertiary cases


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

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


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?

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


What are some factors that help shape an epi curve?

Host - immunity or resistance to dz. Direct transmission

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



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

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)


What are negative determinants?

Risk factors for dz


T/F: Determinants are randomly distributed


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


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



What are some examples of physical environment determinants?

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


Why are determinants important to know?

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


What is a primary determinant?

A MAJOR contributing factor, usually a necessary one


What is a secondary determinant?

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


What is the different between intrinsic and extrinsic determinants?

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

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


Which determinants are easier to modify, intrinsic or extrinsic?



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



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

Mutation rate and resistance


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

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


In what ways can antibiotic resistance be obtained?

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