That's the problem with some viruses. They take a long time killing the host, thereby allowing the host to infect a number of people before dying. AIDS, unfortunately, has been one of those diseases. Certain outbreaks, like Ebola, are highly deadly, but often "burn out" before too many people pass it on.
Sure. Morbidity is ALWAYS a bell curve. Some curves are higher than others, narrowing the curve (due to rapid mortality), some are lower (and may be broader), due to slower mortality. But it is always a bell curve. Ominous.