On the 23rd of August 2010, The FDA confirmed that there is mouse leukemia virus (MLV's) in humans. They found it in 85.5% of those who have CFS and in up to 7% of the general population. (In Japan? it was found that 2% of normal population have it). http://www.nih.gov/researchmatters/august2010/08302010chronicfatigue.htm
At this point of time, no one knows what this virus does!!! but its being connected to CFS, aggressive prostate cancer and being find in higher concentations then the normal population in atypical MS and also autism.
The WPI discovered this kind of virus (XMLV) in high rates of those who have CFS in Oct/Sept last year.
Anyway.. this is something those who have a lot of strange symptoms should be keeping an eye out for more info on this in case this is what is causing your issues. This virus is a retro virus.. so sits in the body (no one knows how long it can sit dormant but once you have it, you have it for life much like the AIDS virus).
I think this week.. an approved test was just put out to the public!!. Currently the blood banks are contaminated with this virus and the health depts. are trying to work out what to do about it... (so i think that is why not much has been made public about it! .. i guess they may make it more public once they have the blood banks clear of it and know more about the virus)