Recently, a small study has revealed that ticks might be one way XMRV is passed on. The study is being done by Dr. Eva Sapi and Dr. Joe Brewer. The connection was discovered with a sample of chronic lyme disease patients showing 90% infectivity rates with XMRV and MLV's. It is coincidental that the symptoms of Chronic Lyme, and Chronic fatigue syndrome are almost impossible to differentiate. It also explains why despite antibiotic treatments, these patients fail to show improvements. Ticks are already known to carry a form of viral encephalitis.
This points to a likely zoonotic host for XMRV - XMRV could be a new emerging zoonotic disease. Figuring out the host will require the cooperation from veterinary researchers. From transplant medicine, it is already known that pigs are full of endogenous retroviruses. Deer are the primary host of ticks, although they can attach to mammals, birds, and occasionally reptiles and amphibians. A study done in Connecticut shows that lyme disease incidence dropped in proportion to deer population - a 74% reduction in deer population resulted in a 90% drop in Lyme disease in humans.
A hunter from Nevada messaged me last summer, where he denotes "In 1984, there were deer everywhere. I would see deer killed on the road daily. The following year, there was a die-off. We had gone hunting, and at the time my son was 16 - he became ill that fall, and he never got better. Six years ago, he was diagnosed with Lymphoma, and became better after aggressive chemotherapy."