What kind of an epidemic curve is this?

A point source epidemic.

A continuous point source epidemic.

A propagated source epidemic.

None of the above.

That is Correct!

Point sources outbreaks involve a common source, such as contaminated food or an infected food handler, and all the exposures tend to occur in a relatively brief period. Consequently, point source outbreaks tend to have epidemic curves with a rapid increase in cases followed by a somewhat slower decline, and all of the cases tend to all fall within one incubation period.

Epidemic curves tell you more than just whether or not there is an outbreak. Take another look at our epidemic curve. Note that the number of cases rises very quickly, peaks, and then begins to fall off. Also, so far all of the cases are contained within a single incubation period. Also bear in mind that the average incubation period is about 28 days, with a range of 15-50 days.