No. I don't believe so - although the list of human retroviruses is pretty small. But I, at any rate, know of nothing about retroviruses per se that limits them to that form of transmission.
The PR feel of this is unappetizing. I hope it turns out to be real - but even if it is I seriously doubt it is 98% positive in CFS and only 3.7% positive in healthy people. If for no other reason that CFS symptoms are so vague it has to catch a bunch of people with different etiologies (e.g. pure psychiatric).