Selidaphagic

(se-LID-uh-FAY-jick)  An adjective, describing the behavior of someone who reads avidly.  Derived from the Greek word σελῐδηφάγος, meaning “‘devouring the leaves of a book.”

Whereas a bookworm is someone who reads a lot in general, a person is selidaphagic if their manner of reading is intense.  So, the two terms can be used separately; a bookworm may read in a calm, relaxed fashion, and a selidaphagic person (who could also be called a selidaphage) may not read much, but when they do read, they read intensely.