A study published in the US journal, Science,  found a single retrovirus known as XMRV common to 67% of ME patients, compared with fewer than 4% of the general population. Although unable to conclusively prove a link between the virus and the onset of ME, the scientists believe they have made a breakthrough in terms of understanding the causes of the condition.
Researchers at the Whittemore Peterson Institute in Nevada took DNA samples from 101 patients with ME, comparing them with 218 ‘normal’ controls. They found evidence of the XMRV virus in 68 out of 101 ME patients, and less than 4% in people from the control group. Overall, people with CFS were 54 times more likely to contain viral sequences as samples from healthy controls.
The researchers concluded that their findings suggest that XMRV may be a contributing factor in the development of CFS and that the virus could be responsible for some of the abnormal immune response and neurological problems seen in CFS. Others point out that we still do not know whether the infection occurred before or after ME developed and indeed that ME may make people more susceptible to infection with the virus.
M.E. (myalgic encephalomyelitis) or Chronic Fatigue Syndrome (CFS) is a debilitating neurological illness which affects a range of organs in the body, including abnormal immune system function. The cause is not known, but one theory is that certain viruses trigger the disease.
Many ME sufferers have reported that their symptoms began after a viral infection, including glandular fever, Lupus and the herpes simplex virus. This is not the first time CFS/ME has been associated with a chronic viral infection. Indeed the study group of Elaine DeFreitas reported a link between CFS/ME and retroviruses back in 1991. 
This approach in part underpins the novel approach of leading neuroscientist Professor Basant Puri of Imperial College London, whose prescribed treatment involves using highly purified ethyl-EPA which is known to possess strong anti-viral properties.
Prof Puri’s research has shown an organic volume and chemical abnormality in ME brain tissue which he believes can be treated often successfully with the pure fish oil extract EPA, and unrefined evening primrose oil, found in our patented supplement Vegepa. Furthermore EPA has a direct virucidal action, which may explain in part why over 80% of ME patients improve with Vegepa. EPA also has a regulating effect on cytokine levels, which are often very high in ME patients as a result of virak ir toxic stress.
 Lombardi VC, Ruscetti FW, Das Gupta J. Detection of an Infectious Retrovirus, XMRV, in Blood Cells of Patients with Chronic Fatigue Syndrome. Science. Published online October 8 2009.
 DeFreitas E, Hilliard B, Cheney PR, et al. Retroviral sequences related to human T-lymphotropic virus type II in patients with chronic fatigue immune dysfunction syndrome. Proc Natl Acad Sci U S A. 1991 Apr 1;88(7):2922-6.