You wake in a pub and see that it's full of were creatures, and they're all staring at you with a scared look on their faces. As you continue on into the pub you look at your arm. You notice that your arm is covered in thick brown hair. As you continue on into the pub you look in a mirror, and staring back at you is a 7 foot werebear. As you continue into the pub people start to shy away form you. Once you go the bar you ask the weretigress that's the bartender and begin to ask her why everyone is shying away from you, and she begins ro tell you why.
A plague has hit the local area.
In humans it affects only the most vulnerable, the children and the very old, and even than it's little more than a summer cold. 24 hours of sniffles and then it's gone, barely noticeable really.
To sheep however it is fatal and the whole economy of the area is in serious trouble. If this keeps up the area could well be facing famine.
Somebody (enter the PCs) must find the rare herbs needed to make a cure.