I’m puzzled by the Wikipedia version of the story of the woman who “discovered” this ailment in her 2 year old son. It says she reported that doctors started to refuse to see her and her son, asserting that she suffered from Munchausen’s By Proxy. It occurs to me that the proper approach for a 2 year old who is believed to be in such a situation is to remove the child from its parents into a controlled environment for a period of time, to see if the symptoms dissappear. On the other, it’s also reported that the doctors who examined her son couldn’t find anything at all wrong with his skin — no lesions, etc.
The trouble with something like this is that it certainly inspires a lot of cases of which ARE simply psychiatric in nature, and the cases where a real physiological problem is present are apt to get lost in the shuffle of crazies bringing little containers of fibers to their doctors with stories that the fibers crawled out of their skin, only to have lab analysis find that the fibers are identical to those that the patient’s close are made of.
It does sound to me like any real cases are most likely some sort of immune system failure, which would explain why no unusual pathogens are found in lab analysis, but the patients are still getting unusual symptoms not found in most people in whom the same garden variety pathogens are routinely found. It would also explain the lack of evidence of contagion.
Because it is the Wikipedia version, it doesn't have to make sense..