1 Never use a microwave or conventional oven to pre-heat your flask. 2  If your flask has not been used for some time, rinse with warm water to remove any residual odours.  DO NOT overfill your flask. Leave sufficient space in the neck to fit the stopper.
Prevalence is a measure of disease that allows us to determine a person's likelihood of having a disease. Therefore, the number of prevalent cases is the total number of cases of disease existing in a population.
Think of it this way: incidence provides us with information about the current risk of getting a certain disease, while prevalence tells us how many people are living with the condition, regardless of when (or whether) they've been diagnosed with it.