I've read that XMRV can spread the same ways as HIV. Is that true? If so, why do some people get chronic fatigue syndrome when they've never had sex or a blood transfusion?
These are complicated issues, and right now we're too early in the research process to have a lot of definitive answers.
First, remember that scientists are still trying to figure out whether the retrovirus is even linked to chronic fatigue syndrome -- we don't yet know what role, if any, XMRV plays in the cause or transmission of the condition. That means we can't assume that everyone with the illness is XMRV-positive.
Also, if early research is correct and XMRV is transmitted through bodily fluids, like HIV, sex and blood transfusions aren't the only ways it could spread -- it could be passed from mother to child during gestation or breast feeding, for example. It's also possible that XMRV has other modes of transmission. Some research suggests that it may be able to spread through the air, but again, these are just preliminary findings.
Basically, it's just too soon to make assumptions about XMRV or determine what relationship it could have to individual cases of chronic fatigue syndrome.
