Lycanthropes are humanoids with the ability to turn into animals and animal-humanoid hybrid shapes. Natural lycanthropes are born with this ability and have perfect control over their shapechanging. Afflicted lycanthropes contract this ability like a curse or disease from another lycanthrope; they sometimes change form involuntarily.
A creature that catches lycanthropy becomes an afflicted lycanthrope, but shows no symptoms (and does not gain any of the template's adjustments or abilities) until the night of the next full moon, when the victim involuntarily assumes animal form and forgets his or her own identity. The character remains in animal form until the next dawn and remembers nothing about the entire episode (or subsequent episodes) unless he makes a DC 20 Will save, in which case he becomes aware of his condition.
A remove disease or heal spell cast by a cleric of 12th level or higher cures the affliction, provided the character receives the spell within 3 days of the infecting lycanthrope's attack. Alternatively, consuming a dose of wolfsbane gives an afflicted lycanthrope a new Fortitude save to recover from lycanthropy.