An incidence rate is the number of new cases of a disease divided by the number of persons at risk for the disease. 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. A prevalence rate is the total number of cases of a disease existing in a population divided by the total population. So, if a measurement of cancer is taken in a population of 40,000 people and 1,200 were recently diagnosed with cancer and 3,500 are living with cancer, then the prevalence of cancer is 0.118.
Morbidity is another term for illness.
A person can have several co-morbidities simultaneously. So, morbidities can range from Alzheimer s disease to cancer to traumatic brain injury. Morbidities are NOT deaths. Prevalence is a measure often used to determine the level of morbidity in a population. Mortality is another term for death.