You mean why were more ME + samples contaminated? Does it matter if it's contamination?
What an extraordinary question Redruth! Where is your scientific curiosity?! Surely it's obvious why an answer to that question would be so crucial to the debate, and such a valuable piece of knowledge in itself?
Did you read Prof Robin Weiss' paper reviewing historical contamination incidents? It's a very readable overview, albeit a very carefully-timed political paper from a pillar of the establishment, of course. The highlight for me was learning that, in most of the incidents he highlighted as previous contamination, there had actually never been any proper proof that they really
were contamination, and no satisfactory explanation of how the contamination had occurred: it had just been accepted, eventually, that they probably
must have been contamination, and everyone had moved on. Most particularly, he admitted that there was no satisfactory explanation of why the contamination had sometimes affected patient samples at much higher rates than controls, and the only real hypothesis was that maybe the patient samples had been handled more often (and there wasn't even any evidence that they
had been handled more often). The remarkable thing to me was: such "contamination" incidents have (allegedly) been confusing research, creating controversy, and diverting research funds inappropriately for decades...and yet there appears to be no desire on the part of those claiming this is the case to actually get to the bottom of the matter, figure out how this mysterious contamination keeps happening, and thus find out how it can be prevented in the future. That lack of curiousity seem curious to me...
Yes, it matters to know precisely how the alleged contamination occurred, and an explanation is required for how it could be that the patient samples get contaminated at higher rates than the controls, and how it was that the controls all got contaminated at roughly the same rate in multiple positive studies (I'm including the positive prostate cancer studies there, because everything that wasn't 0/0 has found roughly the same background rate of XMRV in controls; in a contamination scenario the statistical likelihood of that is infinitesimally small and that requires an explanation too).
It would matter how such contamination keeps affecting patient samples so disproportionately even if it had been
proved that it is contamination: one would surely want to improve experimental design to avoid this happening again, no? But it is not at all proved that it's contamination, and (here's the crux of the matter, for me) the contamination theory should be subjected to the same kind of rigorous scepticism that has been applied to the positive studies. Posing this question of how it can be that the patient samples get contaminated at such high levels compared to controls is a reasonable question: it's something that the contamination theorists ought to be required to explain, and they should also explain where the contamination came from and how it took place. But where is the rigorous so-called "scepticism" now? Where are the self-styled 'sceptics' when you really need them, eh? They're certainly not busy poring over White and Wessely's garbage and asking searching questions about
that, more's the pity - they appear to prefer softer, less well-defended targets, for some reason...
I really do find this whole reaction of "oh, nobody else can reproduce it, it must have just been contamination, let's move on" quite incredible. I realise that there are budgets to juggle with, and masses of other priorities to consider. But the lack of curiosity here, the lack of desire for a full and proper explanation of observations, just astounds me. When you consider what's at stake, to just let the matter drop without ever getting to the bottom of it would be the height of irresponsibility, and the willingness - nay, the enthusiasm - of the establishment to close down questions like this is just one more reason why so many people (myself included) are losing faith in the integrity of the modern scientific process.
But I suspect I can guess your answer to the above: Contamination in labs is very, very common, actually; despite our best efforts, there's rogue DNA all over our labs and the products we use, and when it happens in experiments we just shrug it off - even if it's contamination with a novel human retrovirus that was created in the lab and has spread unintentionally through an unknown process. That sort of thing is par for the course, and when it happens we just move on because we haven't got time to study
every little thing. Somehow, I still don't find that revelation very reassuring though. Speaking as somebody with "bizarre" and "impossible" symptoms of permanent immune damage (lasting more than 16 years now) that are completely unknown symptoms to medical science (yet familiar to many members of this forum) and which nobody in the medical world seems to have the slightest interest in investigating or even acknowledging in any way...small wonder, really, that when I see a scientific blind spot like this one, in an area of science that would offer a perfect explanation of what has happened to me, that I don't want to see the scientific investigation finished without a proper explanation before it's even begun.
So: I am going to continue to demand a proper investigation and explanation of this science, and I'm going to continue to apply my scepticism not to those who are trying to help, but to those authorities who have so completely and systematically failed the millions who have suffered with ME/CFS/FM/MCS/GWI/WTF/etc for so many decades.