Final answer:
The incidence rate measures new cases of a disease within a specified time frame, essential for assessing risk factors and disease management. It differs from prevalence rate that accounts for all cases in a period. These rates affect understanding of morbidity, the overall disease burden in a population.
Step-by-step explanation:
The incidence rate of an illness refers to the number of new cases that develop in a population during a specified time period. This measure is crucial for understanding the risk factors associated with a disease and for planning prevention strategies. The incidence rate can be contrasted with the prevalence rate, which takes into account all cases, both new and existing, within a certain period, providing a snapshot of the disease's overall burden on the population.
Prevalence is sometimes calculated using the formula: Prevalence = Incidence x Duration. Conversely, Incidence can be derived by dividing Prevalence by Duration. Importantly, these rates are often expressed per 100,000 people to avoid exceptionally small numbers that lack impact when demonstrating disease risk.
Additionally, the incidence and prevalence also contribute to understanding of morbidity, which is the state of being diseased. While incidence focuses solely on new cases, morbidity can include the total number of diseased individuals at a particular time in a population.