I'm thinking something will cause the start of a sickness, and then we'll pick one person/wolf for the sickness to start in, and have it spread to other somehow. Either through bodily fluids, ie Blood, saliva ect. Bites, bacteria, parasite or some other way.
ooo hmm depending on which illness wins (assuming sickness wins this poll) it could be via prey? Like a diseased kill. That way it could be initial infection of the member who make the kill then whom ever eats the kill afterwards? That's just an idea though.