I've seen it published somewhere, but I don't remember. False positives were extremely low. Lower than I trusted initially, but TX and CO have been testing rather intensively and with a low enough positive rate that it seems false positives can't be a huge part of it. TX in particular. They're testing something close to 20,000 deer a year, and only turning up a handful of positives, almost all in clusters around known areas. They turned up a loan deer in a new spot a few years ago and haven't found any more deer there. Could be a false positive. It was a very mature buck that was emaciated and active confused, so it was euthanized and tested. To my knowledge the test does not differentiate between forms of prion disease, so it's possible that the deer had a spontaneous 1/1,000,000 prion disease that natural occurred in deer since they came into being.I do have my wonderings about how accurate the testing is, it is run by the government after all and I'm guessing not the tightest lab protocols...
Again, I've seen supposed accuracy published but I don't remember where. False positives were extremely low. False negatives were higher, which mildly bothered me. I wish I remembered the numbers, or even where I read them. Either way, the testing was reasonably accurate. Nothing it perfect.