Epidemic Curves and Determinants of Disease Flashcards
What is a latent animal?
Microbe is replicating but not yet enough for the host to become infectious.
What is the incubation period?
Microbe is replicating but not symptomatic yet. It does not always correlate with the latent period.
What is infectious disease?
A disease caused by the invasion and multiplication of a living agent in/on a host.
What is infestation?
Invasion, but not multiplicatio of an organism in/on a host (fleas/ticks, sometimes parasites.)
What is a contagious disease?
A disease transmissable from one human/animal to another via direct or airborne routes.
What is a communicable disease?
A disease caused by an agent capable of transmission by direct, airborne or indirect routes from an infected person, animal, plant or contaminated inanimate reservoir.
Why are these distinctions important to public health and epidemiology?
If something is communicable we are worried about water source, soil, vector and also direct contact spread.
What is an epidemic curve?
Represents the number of new cases of disease over time.
Can tell you:
- 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.)*
- About outliers. (With epidemiology you do look at outliers.)*
What does one of these bars stand for?
A wave.
What does each higher “peak” represent?
An incubation period which you will notice on this graph is separated by 3 days of incubation.
What does the Y axis represent on this graph?
The # of new cases seen.
What does X axis represent here?
Here it represents days that have passed but could also be weeks or months depending on graphs (and disease that is being referenced.)
Would a disease like this recover without interference?
No, something needs to be done.
What kind of graph is this?
Common Source Single Point Exposure.
- All animals are exposed at once.*
- All are exposed to the same source of infection.*
- Not contagious–get sick and then get over it.*
Would you need to do something about this type of disease?
No, occuring within one incubation period.
What kind of graph is this?
Common Source with Intermittent Exposure.
- Animals are exposed at different times.*
- Exposed to the same source.*
- Incubation period is NOT clear represented–lack of a pattern.*
- ex: Farmers putting cows out onto pasture and there is a pond that is infected with Leptospirosis. Brought to a different pasture and then reintroduced to pasture and pond again.*
Should someone intervene with a case like this?
Yes
The shape of the epidemiological curve depends on what things?
- Host: Immunity or other resistance to disease or direct transmission.
- Agent: Infectiousness of agent, or latent and and incubation periods, or duration of infectivity.
- Environment: Especially important for indirect routes of transmission.
What is endemic stability?
A situation in which all factors influencing disease are relatively stable, resulting in little fluctuation in disease incidence over time.
- New cases occur at a regular, usually low level.*
- Young individuals may enter the population.*
- Old individuals die or are removed.*
What is the animal term for endemic?
Enzootic
T/F: Most cases that we deal with on a daily basis are epidemic.
False, they are endemic.
What is a determinants?
Factors that help determine the probability, distribution, or severity of a disease in an animal or population of animals.
Determinants can be a determinant for health or a determinant for disease.
ex: Host susceptibility is one kind of derminant –but certainly not the only one.
Why is it important to recognize determinants?
- Identifies animals at particular risk.
- Disease prevention.
- Aids in a differential diagnosis.
What is a primary determinant?
A major contributing factor, usually a necessary one.
What is a secondary determinant?
Factors that make the disease more or less likely; predisposing or enabling factors.
What are intrinsic determinants?
Determinants that are internal to the animal. (age, breed, sex, etc…)
What are extrinsic determinants?
Determinants that are external to the animal. (housing, medical treatment, etc…)
_______ determinants must always be present in order for the disease to occur.
Primary
Aka: necessary causes.
Primary determinants satisfy the _____ ____ ____ test.
Gotta have it.
Everything else is just secondary or just a component cause.
For Bovine Shipping Fever what is the:
Primary intrinsic: ______
Primary extrinsic: ______
Secondary intrinsic: ________
Secondary extrinsic: ______
determinants.
Primary intrinsic: Immunologically naive animals (genetic.)
Primary extrinsic: exposure to shipping.
Secondary intrinsic: they are young (calves.)
Secondary extrinsic: mixing the cows.
Complex interactions between all 3 sectors [host, agent and environment] determine what?
The ultimate outcome (a disease.)
What are the 3 sectors for Flea Bite Hypersensitivity?
Host: Dog or cat
Agent: Fleas
Environment: Humid like the state of FL.
