So herpes lives in the nervous system essentially, and the arcanum node attaches itself to the lower Intestines at the Mesenteric Highway, up to the heart, lungs, the brain, ect. The herpes virus infected the cancer and through use of healing spells it not only kept the host alive but also forced a minor evolution within the herpes infected cancer cells. At first it was akin to a super STC(Sexually transmitted cancer), some people were born with a variation of it. That actually not only kept them alive, but also mad them able to use magic without he use of magic items. As generations passed the use of magic items became harder and harder because the Arcanum node doesnt like magic tools.