Epi curves/Determinants of Dz Flashcards
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?
YES
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
Environment
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
FALSE
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 ___________
Determinants
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?
Extrinsic
T/F: Primary determinants must ALWAYS be there in order for disease to occur
TRUE
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
Genetic diseases are entirely determined by genotype. This makes them _________ determinant of dz
Primary
Genetic susceptibilities are partially determined by genotype and partially determined by other factors. When determined by “other factors” you are referring to ________ determinants.
Secondary
Is diet considered an intrinsic or extrinsic factor?
Extrinsic - more of a management issue
But the body condition score of an animal and nutritional status are intrinsic
T/F: Giving a vaccine is an example of an intrinsic preventative treatment
False - this is extrinsic
The status of the body being immune, however, is intrinsic
What is herd immunity?
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)
