Morbidity is defined as which of the following?

• A. The death rate
• B. The incidence of a specific notifiable disease
• C. The number of new cases of an illness per population at risk in a given amount of time
• D. The prevalence of chronic diseases in a population

Answer: (B)

Morbidity is about the presence and burden of disease in a population. The clearest way to quantify how often illness occurs is to use incidence—the number of new cases of a disease per population at risk over a defined period. This captures new illness and the risk people face, which is a direct measure of morbidity. Saying morbidity is the incidence of a specific notifiable disease is a concrete, practical example public health uses because those diseases are monitored and reported to track illness levels. However, morbidity isn’t limited to notifiable diseases, and it can also be described by prevalence, which counts all existing cases at a given time. The other choices mix in death (mortality) or refer to existing cases rather than new ones, so incidence of disease over time remains the standard way to represent morbidity.