What is used to represent the number of new cases of disease over time?
Epidemic Curves
What factors of disease can we learn from epidemic curves?
Most probable source of outbreak If pathogen is contagious If outbreak is ending or will continue Incubation period (sometimes) Outliers
Should outliers in epidemic curves be considered or ignored?
Always consider! Early outliers can be early cases of the disease that weren’t noticed at first, but they can also be unrelated to the current outbreak.
Early epidemic curves are based mainly on what?
Clinical signs and symptoms
What factors will cause waves of infection to stop?
All susceptibles die or become resistant. Prophylaxis ends disease (vaccines)
This curve features exposure followed by waves of secondary and tertiary cases of disease. What type of source is indicated?
Propagated source. Common with contagious diseases.
The areas of low # cases between waves of disease indicate what?
Incubation period
The following curve indicates what type of exposure to disease?
Common source, single point exposure. All animals are exposed at the same time from the same source.
T/F: Epidemic curves such as the one featured are common with contagious disease.
FALSE
Contagious diseases produce a propagated source curve.
If we know the point of exposure, can this curve tell us anything about the incubation period?
YES! We can determine the minimum, average, and maximum incubation times.
This type of curve indicates what type of exposure?
Common source with intermittent exposure.
All animals are exposed to the same source, but at different times.
What can this Common Source/Intermittent Exposure curve tell us about the incubation period?
Not really anything, since everyone is getting infected at different times.
Host factors influencing the shape of an epidemiological curve:
Immunity or resistance
Direct transmission
Pathogen factors influencing epidemiological curves:
Infectiousness of agent
Latent and incubation periods
Duration of infectivity
T/F: Enviromnent doesn’t affect an epidemiological curve.
FALSE
Host factors, agent factors, AND environmental factors incluence the shape of the curve
What’s up with endemic stability?
All factors influencing disease are relatively stable, resulting in little fluctuation in disease incidence over time.
Factors that help determine the probability, distribution, or severity of a disease in an animal or population.
Determinants
Health status is determined by the COMBINED ______.
Determinants of health
Which is more important to health status, zip code or genetic code?
Zip code!
5 Categories of health determinants for animals
Social environment (animal and human social factors)
Economic
Physical environment (food, water, shelter)
Animal individual characteristics
Etiologic agent
If a determinant is a major contributing factor and is usually necessary for disease, it is called a _______ determinant
Primary
Predisposing or enabling factors are called _______ determinants.
Secondary
Age, breed and sex are examples are examples of ______ determinants
Intrinsic
Housing and medical care are ______ determinants.
Extrinsic
Spores in the soil and susceptible cattle are what kind of factors for anthrax disease?
Primary determinants, or necessary causes in Rothman’s model of diseases
Mutations are agent based disease determinants, and include:
increased infectivity
Ability to infect new species
Aqcuisition of new toxins
Immune system invasion
What 3 ways can antimicrobial resistance be obtained?
de novo
mutation
lateral transfer
Environmental determinants include:
Demographics
Macroclimate
Microclimate
Housing/Crowding
Diet
Stress
Diet is an ______ determinant, while nutrition status and BCS are _______ determinants.
Extrinsic/envorinmental
Intrinsic/host
Genetic diseases are ______ determined by genotype, and genetic susceptibilities are ______ determined by genotype.
entirely
partially
Why are certain breeds predisposed to certain diseases?
Similar genotypes within breeds
Breed determines size, color, etc
