How important is the setting of Dracula and what does it influence?

The answer here is found in the shifting setting.  The early chapters take place in the very under developed town of Transylvania, Romania.  Eastern Europe is portrayed as rustic, primitive, virtually medieval.  The common person is described as quaint but highly superstitious.  These people live in fear of the undead and even cooperate with these creatures rather than confronting them.

The setting soon moves to the culturally sophisticated, scientifically advanced, and spiritually liberated 19th century London.  Here Dracula is confronted by people of science (Dr. Van Helsing and Seward), a modern women (Mina Harker), a wealthy if somwhat reckless American (Quincy), and a member of the English aristocracy (Godalming) all of whom work together against Dracula regardless of their personal and class distinctions.

What is the point?  The "Scientific Revolution" was in full sway  during this period and many notables of the period questioned whether superstition and science could co-exist.  In this context, Dracula can be seen as a novel about the primacy of human reason over superstion when dealing with the problem of evil.