"This symposium will ...reveal recent advances in the testing and screening of the blood supply" Safe to assume those advances have now been made. And what George describes of this paper does seem to take the lid off the fact that the X/P factors have been resolved. I'm curious about the "about 80 years ago" bit, George. How accurate do you think that's likely to be? Any guess as to margin of error with that? Because 80 years ago would be 1930 or so, around about the time of a candidate for the first documented outbreak of ME, I think?