Before I was diagnosed with CFS, my D.O. had me try chelating heavy metals with a product called Chelex (DMSA, EDTA, Cilantro..). Of particuliar interest was mercury toxicity. After a month, I was feeling a little better. Less brain fog, but still sleeping through lunch and enjoying the TX summer heat: 100°F felt good to me. My body temp was 95.7°F on the average. My D.O. decided to test for Epstein Barr & Cytomegalo virus and the numbers were off the lab scale! Not active but chronic. I was put on transfer factors and boy did I herx. After 3 months, I could handle 2 capsules/day. Now at 6 months I can occasionally handle 3 cap/day. I did the "Mikie pulse" from time to time and this did help me too. My body temp is now averaging 98.3°F, brain fog worsens with TF pulsing but perhaps better. All this to say,(strictly as a theory) that perhaps what started the weak immune system and hence the "opportunistic" viruses was mercury exposure. Has anyone else been tested for heavy metal? Esp mercury? I understand that hair testing is the best test for this, not that the numbers mean anything, but any #>0 is cause for concern.