What type of epidemic curve has a distribution of cases that goes up rapidly and then drops off and is usually the result of a common exposure to a single etiologic agent?

The type of epidemic curve you are describing is known as a "point-source epidemic curve." This curve reflects a rapid increase in cases following a common exposure to an etiologic agent, such as contaminated food or water, followed by a sharp decline as the exposure ceases. The steep rise indicates that many individuals were exposed simultaneously, while the quick drop-off suggests that the outbreak was short-lived.