Montag has caught the "dis-ease". What are his symptoms?

The symptoms of Guy Montag's "dis-ease" is his transformation from a passive conformist to the mores of his society to one who rebels against its dehumanization of citizens, by engaging in meaningful conversations with other people and who can read and think independently and by secretly possessing books.

A clue to what the condition is that Montag develops is in Ray Bradbury's purposeful hyphen between the syllables of "dis-ease," dividing the word into the prefix...

The symptoms of Guy Montag's "dis-ease" is his transformation from a passive conformist to the mores of his society to one who rebels against its dehumanization of citizens, by engaging in meaningful conversations with other people and who can read and think independently and by secretly possessing books.

A clue to what the condition is that Montag develops is in Ray Bradbury's purposeful hyphen between the syllables of "dis-ease," dividing the word into the prefix "dis-" which means "not" and "ease" which means comfort. Thus, the word "dis-ease" is meant to be figurative, implying that Guy Montag has become uncomfortable and dissatisfied with his life. The causes of this "disease" begin with his meeting of Clarisse McClellan one evening as he returns home from work. For, in his conversation with the ebullient Clarisse, Montag is introduced to ideas he has never considered: the delight of catching rain on one's tongue, the wonder of being in love and experiencing happiness, the enjoyment of nature, the wonder and pleasure of reading. After his meeting with Clarisse, Montag realizes how empty his marriage is with his estranged wife, Mildred., and how devoid she is of real feelings.

 The other cause of his "dis-ease" is Montag's experience at the home of a woman who owns countless books. When he and the other firemen start to burn these books, they tell her to leave the house, but she refuses; instead, she lights the match that ignites the terrible blaze, choosing to die with her books rather than depart from them. Moved that someone would love books more than life, Montag's curiosity is aroused and he retains some books that he has impulsively caught as they blow through the air during the blaze. He sneaks them home with him, too, and tries to read what is in them.

Thus, Montag's "dis-ease" causes him to change from a complacent member of his society to one who becomes a non-conformist, rebelling against dictates such as those that forbid the ownership of books and actually talking with people about real ideas.