Amphetamines cause users to discover this as the disease caused by their long time abuse of speed. The fibers are simply cotton, rayon, nylon, fibers from clothing, sheets & pillow cases, towels, and cotton balls, crusted into the lesions from their constant digging, scratching, and tweezering scabs on their sores. They will not accept the fact however because the nerves in their face are so damaged they feel things crawling, stinging, and itching under their skin.
There has not been a Morgellon's sufferer who's condition has not spontaneously cured itself once they have been fitted with mittens on their hands so they can't dig at their sores.