The target gains the eldritch ague spellblight.

Eldritch ague manifests itself as a sickness that is debilitating to spellcasters. A spellcaster with this spellblight is sickened until the curse is removed. When the subject of the curse casts a spell, she is overcome with shaking for 1 round, requiring any Spellcasting or the use of a spell-like ability during that time to succeed at a Concentration check (DC 15 + twice the spell level of the spell being cast). If she fails the save, the spell and the Action to cast it is lost.

While a curse, eldritch ague acts much like a Disease, and creatures with Immunity to Disease are also immune to eldritch ague. Remove Disease cures eldritch ague; unlike with most spellblights, using this spell to remove the spellblight does not impose a –5 Caster Level check Penalty.