In the opening paragragh of "The Masque of the Red Death", what technique does Poe use to establish a tone of suspense?

Poe's word choice is his first paragraph paints a gruesome
picture of a horrible, painful, deadly experience known as the "Red Death."  Words like
devastated, fatal, horror, hideous and victim
are not happy words--they are words we associate with terror and death.  He then goes on
to describe the symptoms and manifestations of the illness in particular
detail--mentioning blood, sharp pains, dizziness, bleeding, and the scarlet stains.  If
this is not enough to terrorize the reader, Poe then says that if a person is afflicted
with the disease, other people will shun him or her and not be willing to
help.

As readers, we are asking ourselves why Poe is
describing such horrible suffering and pain in such detail--it must be essential to the
rest of the story for some gruesome reason.

Then, without
so much of a transition or explanation, Poe starts his next paragraph with Prince
Prospero (prosperous, which those who are afflicted with the illness are not) being
happy and wise.  Again, we as the reader are left wondering--why did he tell us about
the illness?  How is that going to come into play in this
story?

The juxtaposition of the horrible suffering of the
misfortune and the happy-go-lucky prosperous prince is jarring, to say the
least.