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Similar symptoms to the epidemic widely known as "Bieber fever" but with a level of maturity and elegance not seen amongst those suffering from "Bieber fever." Strikes most often prior to the release of a new book or movie about or relating to Harry Potter. May leave victims in a euphoric state that will, when it fades, plunge the victim into Post Potter Depression.
Bill: "When the final Harry Potter movie came out, I felt like I had Potter Fever."

Bob: "Careful Bill, Potter Fever and Post Potter Depression often go hand-in-hand."
by TeamPottermore August 13, 2011