Interesting thread Hope123. My own main symptom I describe as "malaise", further expanded as "feeling crap". I can't relate it directly to any pre-ME experiences, so common terms like "flu-like" are inadequate. It's all around my head - severe, prolonged headache, dizziness (even that's not exactly right!), light-headedness (relates to low blood-sugar which I suffer as a reaction to sugar). The more I do the worse it gets and is accompanied by fatigue - also inadequate, as it's a kind of feeling-ill fatigue. That's why I hate the term CFS. Incidentally similar to you Hope123, I was a triathlete pre-ME. I think this has a connection - overtraining coupled with a stressful job possibly made me susceptible (to XMRV or whatever else). Maybe we (or researchers/clinicians) can learn something from all the input here. Is there a set of symptoms which chracterises XMRV-ME for example? Gather symptom data/knowledge on all XMRV-positives. Is it possible to identify subsets of the ME/CFS population and relate this to different causal factors. Somebody also made a good point that multiple incidence in families occurs but is not recognised, pointing to infectious cause. I think there's a whole heap of knowledge out there which could be a rich source of answers, but I'm not sure the labs are the right/only place to find them quickly. I'm sure these thoughts have been expressed before, so apologies. It's cathartic to post though.