The best way to discover about the wild mind is to meet someone in the throws of it. From the time they are touched until they turn fully feral is 2d6+1 days. First thing to go is the ability to concentrate this is accompanied by vacant stares and the feeling of having lost ones train of thought this stage also sees grooming habits go out the window. The next manifestation is physical, either hair has started to grow on unusual parts of the body or scales, nails become thick and claw like, this stage is accompanied by a penchant for eating unusually things. At the third stage speech is lost and the ability to make meaningful communication follows close after. This whole process can take between 3 days and 2 weeks. A lucky person has enough time to find a magical healer who has the ability to remove curses. The less lucky person reaches full wildness and condition becomes permanent. Optionally players can make a saving throw to slow down the process: a con save of 12 can double the time the curse will take before fully going into affect.
The rangers' tower contains a victim which can serve as an opportunity to freak the PCs out. Alternatively I can make them tell the table about a person they know and then bring that person into the story as a victim of wild mind that they run into wandering aimlessly in the wild.