Possibly a little premature, but I've been wondering what the likely lie of the land will be 'post-XMRV'? For the sake of discussion, let's get two assumptions out of the way immediately : That's XMRV is strongly associated with XMRV; That XMRV is wholly or partially causative. The first assumption now appears to be confirmed while there are strong hints that confirmation of the latter will follow soon. We can only wait and see. In the meantime, two related issues have been bothering me : Is XMRV+ a diagnosis of ME/CFS?, and What happens to those diagnosed with CFS who do not test positive for XMRV? Is XMRV+ a diagnosis of ME/CFS? We all know the issues of case definitions and prevalence so no need for me to repeat them. If we assume that the Canadian Criteria prevalence rate equates to around 0.5% of the population, that the prevalence rate using the CDC's empirical criteria is around 2%, and that the approximately 95% XMRV+ rate for a CCD cohort is correct, then approximately a possible one quarter of all patients currently diagnosed with 'CFS' will test positive for XMRV. But XMRV has also been linked with prostate cancer, possibly NH Lymphoma and may be implicated it other illness such as autism, atypical MS etc not to mention the possibility that 3-7% of the population as a whole may test positive for XMRV. There is also the suspicion that XMRV may lie latent until triggered by something else. So : (a) the rate of XMRV causing diseases of any kind in the population is likely to be much higher than the 0.5% of accounted for by those diagnosed with CCD CFS; (b) testing positive for XMRV only represents a risk factor for developing a range of illnesses. It is the presence of XMRV plus the typical symptoms that determines whether you have XMRV mediated 'CFS', XMRV mediated prostate cancer etc. What happens to those diagnosed with CFS who do not test positive for XMRV? Clearly this is weighing on many people's minds, particularly those of use with mild/moderate symptoms or who don't recall a viral onset. On the other hand, lets face it, we have been banging on for years that lax case definitions have led to researchers studying patient cohorts that have a possibly large proportion of people who 'do not have real ME/CFS'. The problem is that losing one quarter of their patients to XMRV is a setback, but not a disaster for the psych lobby. In fact, without wishing to scaremonger, the position for XMRV- CFS patients may become worse. Rather that 'CFS' being complex and unexplained for which the 'pragmatic' treatment is CBT and GET, the psychs can say there you are they found the pathogen that causes 'ME' and you don't have it you have CFS, a somatoform illness, period. I think we can see this process at work already with the CDC's claims that they never studied ME and supposedly innocent questions cropping up on 'other science forums' like are ME and CFS the same thing. There's also the danger that the best researchers will inevitably be drawn to the XMRV+ cohort to the detriment of others. What I would hope would happen would be that, once XMRV is proven to cause ME/CFS, that this is enough to strongly suggest that other unidentified pathogens should be considered as the default assumption in investigating those who share the symptoms of ME/CFS under strict diagnostic criteria but who do not test XMRV+. In fact I'd go further to suggest that another pathogen should be considered likely for anyone falling within the broader definition of CFS, including those who may be suspected of having clinical depression or other 'psychiatric' illnesses. The recently discussed 'massive parallel pathogen arrays' (excuse me if the terminology is wrong -I hope you know what I mean) may be the type of tool that can relatively rapidly screen a wide range illnesses. Hopefully also the immunological findings coming from WPI will start to drill deeper into how pathogens like XMRV cause the myriad symptoms found in XMRV, including psychological symptoms, and these finding cast a little more light on 'psychiatric' and other 'medically unexplained illnesses'. Without wishing to delay the research and hopefully treatment for those found to be XMRV+, I'd like to see the approach and techniques used by WPI applied to a much broader population as early as possible. Otherwise, I feel many of us are in for 'interesting times' as the Chinese would say.