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From: TSS ()
CJD WATCH MESSAGE BOARD No one is known to have contracted variant CJD in the US. But last year a US-born cow was found to have BSE, and a related disease called CWD afflicts elk and deer in states close to Idaho. So not surprisingly, campaigners and conspiracy theorists who specialise in CJD latched onto Idaho's cluster of CJD cases as evidence that the authorities are covering things up: that there are way more mad cows, or mad deer, in the US diet than they admit. Scientists hate this kind of thing, not least because they are often included among those accused of the cover-up. It is also true that many scare stories of this kind rely on people's ignorance of statistics. Take Idaho. The cluster of CJD cases there may be the result of nothing more sinister than the workings of chance, says Tim Sly, a public health expert at Ryerson University in Toronto. If a disease is expected to occur at 1 in a million overall, and we imagine the US's population split into subgroups of 1 million each, then the chances of exactly one case occurring in every subgroup in any one year is around 10 ^ -19 That's 1 in 10 billion billion. It is virtually certain that some of the hypothetical subgroups will have several cases and some none. Still, as Sly points out, you don't get news stories saying, "Our state didn't have any CJD this year, and we should have had at least one case." In fact, over the last 20 years, Idaho has had on average about 1.3 cases per million per year. That's close to the predicted incidence. What's more, the 1-in-a-million average is probably lower than the true incidence. Surveillance for CJD is notoriously patchy, and the number of cases typically rises when it improves. The recent flurry of diagnoses in Idaho happened after the state decided that, with all the worries over BSE, doctors should report every case of CJD. But even if there is nothing amiss in Idaho, does that mean we should be telling the conspiracy theorists to shut up and leave public discourse and policy to the select few who understand statistics? Internet commentator Henry Niman clearly doesn't think so. He has tracked the unfolding saga of bird flu, and has posted on his website his own worst-case interpretations for every twist. These have occasionally been uncritically quoted by the press, to the annoyance of some scientists, leading one prominent public health expert to ask if there wasn't some legal way to shut Niman down. But annoying as these conspiracy theorists can sometimes be, suppressing them would be a bad idea. Part of the reason the authorities are paying close attention to CJD in Idaho is because of the spotlight that internet campaigners have brought to bear. Without that pressure, they would not have gone back and looked at the incidence over the last 20 years, and they would not have improved surveillance. The Idaho CJD cluster may just be bad luck. But if ever something does go wrong it will show up as just such a cluster of cases. Can we trust the authorities to tell us when that happens? Their track record is not reassuring. The campaigners' attention to the smallest of rumours has at times helped defeat efforts to suppress important news. The heroic reporters who told a Chinese-language website about the large numbers of wild birds that had died from flu at Qinghai Lake in central China, and suspicions of human cases nearby, would probably have been overlooked by world media had it not been for Niman, who translated and posted their reports. Would it be better if we just let experts gather together in exclusive chat rooms, decide what was happening, and then tell us all? Possibly. Except that scientists, like any other group, have their own agendas, and these may not necessarily serve the greater good. The recreation of the deadly 1918 flu virus this month was an exciting piece of science, but was it worth the risk it would pose to public health if it escaped? There are questions: the review process was far from transparent. How do we know this? From internet campaigners and conspiracy theorists. Scientists have usually had to work hard to achieve their expertise, and with this can come a nasty streak of elitism. Some would prefer not to let those less expert than themselves have their say. True, uninformed commentators - especially those who fail to grasp the basics of statistics - can be a distraction from what experts believe to be the job in hand. But the same could be said for any opposition to the powers that be in a democracy. The conspiracy theorists may be monomaniacs, but they keep a sterner, more unyielding eye on officialdom and its scientists than we poor journalists ever can. We need them. http://www.newscientist.com/channel/opinion/mg18825212.900 http://www.bseinquiry.gov.uk/files/mb/m09/tab05.pdf AS of July 31, 2005, there were 120 scrapie infected soure flocks (figure 3). There were 16 new infected and source flocks reorted in July (Figure 4) with a total of 143 flocks reported for FY 2005 (Figure 5). The total infected and source flocks that have been released in FY 2005 are 89 (Figure 6), with 8 flocks released in July. The ratio of infected and source flocks released to newly infected and source flocks for FY = 0.62 : 1. IN addition, as of July 31, 2005, 524 scrapie cases have been confirmed and reported by the National Veterinary Services Laboratories (NVSL), of which 116 were RSSS cases (Figure 7). This includes 76 newly confirmed cases in July 2005 (Figure 8). Fifteen cases of scrapie in goats have been reported since 1990 (Figure 9). The last goat case was reported in May 2005. ........... snip... http://www.aphis.usda.gov/vs/nahps/scrapie/monthly_report/monthly-report.html SCRAPIE USA MONTHLY REPORT 2005 AS of March 31, 2005, there were 70 scrapie infected source flocks (Figure FULL TEXT ; http://www.aphis.usda.gov/vs/nahps/scrapie/monthly_report/monthly-report.html
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