I read a few articles on the XMRV studies and they stated researchers felt that XMRV was a trigger and/or coinfection but not the sole cause. I did some basic math and think I figured out why. This is very encouraging because it means that exposure isn't anymore than a temporary illness unless you have the cofactor present. I believe the cofactor is L-form, cell wall deficient bacteria. Logically you can cure the disease by killing the bacteria. The incidence of chronic fatigue syndrome in the USA is 0.7% of the population. (2.2 million patients/307 million total population). The reported healthy control group rate for XMRV incidence was 4%. Therefore the XMRV incidence was lower in control non-CFS patients than the incidence in the general population. We expect it to decrease if XMRV is triggering it and the percentage tells us whether or not cofactors are involved. If CFS is only caused by XMRV there should be a 100% decrease with none not getting infected. According to this data, CFS incidence increased by only about 75%, but not 100%. So 25% [calculated as(7%-4%)/4%] of those infected don't get CFS from XMRV infection, the rest are infected. Why? There must be a cofactor...hence L-form bacteria and other conditions (vitamin D intake, sun exposure, etc). Correction: due to a math error previous XMRV rate was overestimated. Using the new figure, this provides compelling evidence that XMRV is just a trigger.