Hi Amberlin,
As you can see, nobody really has a definitive answer. We just don't know. Lots of guessing however, and the following is my best guess (at least for now).
My perspective - CFS/FM is a result of trauma. This trauma in turn results in varying degrees of dysfunction of the brain and nervous system. This in turn leads to a domino like effect where the major regulatory mechanisms of our body (endocrine, immune, digestive, detoxification, etc.) begin to lose their functional capabilities.
The degree of symptoms anyone experiences I think corresponds to a great degree how much these regulatory mechanisms have been compromised.
I think in some cases the trauma can be a result of pathogens (viruses, mycoplasmas, etc.), and theoretically contagious. Some pathogens (such as epstein barr virus for example) will be enough of a trauma for some people to develop CFS or FM. This will not happen with most people however.
Just my 2 cents worth. Also, I believe I have CFS because of a genetic predisposition and a serious head injury at age 15.
Regards, Wayne
P.S. As you read on this board, it's quite amazing the remarkable variety of traumas that people share as the starting point of their current health difficulties. Just a few include:
Lyme, head injury, viral infection, mycoplasma infection, whiplash injury, surgical trauma, chemical exposure trauma, long-standing stress conditions, vaccinations, antibiotics exposure, etc. The list seems almost endless.
[This Message was Edited on 01/11/2008]