Disease that changes allelic frequencies is both bottleneck effect and natural selection?

This is an example of natural selection caused by a changing environment. The H-W principle is actually impossible in nature because conditions are always changing in one way or another, so individuals are always being exposed to natural selection.
This is an example of selection. The alleles among the population may not have changed, but the disease has suddenly altered the environment and so the recessive alleles (in your example) have been selected for reproduction. If it can be assumed that there are other members of this organism elsewhere who still retain the typical balance of dominant and recessive alleles because they were not affected by the change of environment (the disease), then the HWP would still apply to the entire population of this organism, and natural selection would upset the balance only in those organisms affected by the disease.

> a disease has swept a population and has killed off only individuals with specific dominant phenotypes

That's selection, not genetic drift.