A continuous source outbreak is an epidemic in which the causative agent (contaminated drinking water or spoiled food) infects people who encounter it over time.
In contrast, in a point source outbreak, people are exposed to the same source for a short period, such as a single serving or an event. Then the number of cases rapidly increases to a peak and gradually decreases. The overall incidence occurs during the disease’s incubation period.
An epidemic curve defines a point source outbreak with a pointed upward slope and a progressive downward slope. A point source outbreak is an expected base outbreak with a short exposure time and all cases occurring within a single observation period.