Ergot, a fungal diseas comonly produced to rye, wheat and barely is also the orgins of the discovery of LSD and is largely believed to be the primary reason people in midieval times believed in and held witch trials for werewolves/lycanthropy (having its highest consintration in France due to weather conditions and mostly harvesting rye making it more subseptible to producing the Ergot fungi) Other more minimal factors could well include people with hypertrichosts (excessive body hair) and “patients” suffering adverse affects to herblore “witch” remedies.