I don't think so, but you could easily make one. You could just remove the xml define for the event's trigger entirely (it is found in C:\Program Files\Firaxis Games\Sid Meier's Civilization 4\Beyond the Sword\Mods\Fall from Heaven 2 030\Assets\XML\Events\CIV4EventTriggerInfos.xml), but if I were you I's probably just change the <iPercentGamesActive> tag for the Blight Trigger from 100 to 0.