What this suffix does
The suffix -mania comes from Greek "mania" (madness, frenzy) and names an obsession, compulsion or extreme passion toward something. From "klepto-" (steal) comes "kleptomania"; from "pyro-" (fire) comes "pyromania".
Spanish cognates are almost identical: kleptomania → cleptomanía, pyromania → piromanía, megalomania → megalomanía.
Clinical vs popular use
-mania has two registers:
Clinical/psychiatric: kleptomania (compulsion to steal), pyromania (compulsion to set fires), dipsomania (compulsive alcoholism), monomania (obsession with a single idea).
Popular/informal: Beatlemania (extreme Beatles fandom), Linsanity, bikemania. In this use, -mania simply means extreme enthusiasm, not a disorder. "Soccer mania swept the country."
The word family: -mania, -maniac, -maniacal
From -mania derive:
-mania = the obsession (pyromania)
-maniac = the obsessed person (pyromaniac)
-maniacal = the adjective (maniacal laughter)
megalomania → megalomaniac: someone who believes they have extreme power or importance.
kleptomania → kleptomaniac: someone with a compulsion to steal.