As always, this page is work in progress and currently just a scratch pad – and not very up to date.
Etiology is asking the question: "What causes it?". Well, it hasn't be established what causes ME/CFS, but there are some theories.
I must admit, I'm biased: As I write this the enterovirus-hypothesis is the most plausible for me.
These are hypothesis about associations which have some empirical grounds (e.g. clinical and epidemiologic observations, response to drugs, lab tests, etc.).
Ramsay, Mowbray, Chia
ME/CFS is definitley not caused by XMRV (nor "HGRV"), neither is any other disease caused by these retroviruses
Human herpes viruses (HHV)
Stratton (Vanderbilt), Wheldon
Hypothesis without (current) proponents
There was (or is) some research or some speculation about association, but nobody is pushing these theories at the moment.
Retrovirus (other than XMRV)
Findings were probably due to lab contamination, the last tests DeFreitas were no better than throwing darts, as she admitted.
Unknown virus (other than one of the above)
It could be. Let's see if Ian Lipkin finds something.
It is unlikely that a genetic cause affects so many people so profoundly – but genetic differences might play a role with regards to an pathogen.
Human endogenous retroviruses (HERV)
Should be same as genetic causes.
Strauss, Wessley, Sharpe
I don't think elektrosmog is causative, but I know that the people complaining about elektrosmog have real health problems (as in not psychosomatic or any such bullshit).