prevalence and incidence rate

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OUR PRESENTATION

Measures of disease occurrence:

PrevalenceIncidence rate

Prevalence

Prevalence (sometimes called point prevalence) is a measure of the number of animals with the disease of interest at one point in time, as a proportion of the total number of animals in the population.

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Incidence rateIncidence rate (specifically true incidence or incidence density rate) is a measure of the average speed at which the disease is spreading.

Incidence rate is the total number of new cases of disease divided by the total time that each animal in the population was at risk of getting the disease.

For simplicity this can usually be calculated as:

Prevalence versus incidence rate The two are related, according to the duration of disease.

A disease with a high incidence rate but of very short duration will have a relatively low prevalence.

A disease of relatively low incidence rate with a long duration will have a high prevalence.

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