I said:
The ambiguity of my post was that it could be read as saying CFS = PIFS. What I meant was, the Oxford definition specifically spells out the PIFS is a subset of CFS.
I don't think other definitions of ME/CFS make any stipulation about causes.
Even the now discredited Oxford criteria which only required chronic disabling fatigue, not PEM and other symptoms, specifically included post-infectious fatigue along with some psychiatric conditions such as depression.
I think my sentence was ambiguous. We're probably on the same page here. I've just checked the Oxford definition Link to article. It described CFS as chronic disabling fatigue for at least 6 months. It lists various psychiatric disorders as exclusionary, but also says "Other psychiatric disorders (including depressive illness, anxiety disorders, and hyperventilation syndrome) are not necessarily reasons for exclusion." It includes PIFS as a subtype of CFS: "Post-infectious fatigue syndrome (PIFS) This is a subtype of CFS which either follows an infection or is associated with a current infection..."Really? I'd like a link of that. I'm not aware of any definition that requires post-infectious fatigue. If it indeed does, it is wrong.
The ambiguity of my post was that it could be read as saying CFS = PIFS. What I meant was, the Oxford definition specifically spells out the PIFS is a subset of CFS.
I don't think other definitions of ME/CFS make any stipulation about causes.