영국서 ‘인간광우병’ 대량 발병 가능성
연합뉴스 기사등록 : 2007-11-10 오후 06:11:47
광우병에 걸린 소고기를 과거 수년간 먹은 결과로 영국에서 치명적 뇌질환이 대량 발병할 위험이 있다는 경고가 나왔다.
영국 정부 자문관이자 저명한 `인간 광우병’ 전문가인 존 컬린지 런던 유니버시티 칼리지 교수는 광우병(BSE.우해면양뇌증), 크로이츠펠트-야콥병 및 다른 신경변성질환에 대한 새로운 이론을 공개하는 자리에서 이같이 전망했다고 텔레그래프 인터넷판이 10일 전했다.
영국에서 일명 ‘인간 광우병’인 변형 크로이츠펠트-야콥병 발병건수가 올들어 4건에 지나지 않는 등 점차 줄어들고 있음에도 불구하고 컬린지 교수는 유전적으로 취약한 사람들이 지금까지 이 병으로 사망해왔다는 사실을 상기시키면 “우려를 그칠수 없다”고 말했다.
그는 광우병 소고기 가운데 감염을 일으킬수 있는 분량의 소고기가 지난 1980-1996년 수백만건을 통해 섭취됐다면서 인간 광우병은 별다른 증상없이 인간의 몸 속에서 수십년 동안 `조용히’ 잠복할 수도 있다는 증거가 있다고 말했다.
그는 광우병과 관련된 또다른 인간 질병인 쿠루병의 경우, 최단 잠복기가 5년 정도라고 말했다. 그러면서 유아들이 오염된 유아식을 통해 광우병에 노출됐는데도 불구하고 12세 미만 어린이에게 발병이 일어나지 않았던 것은 눈여겨 볼만한 일이라고 설명했다.
컬린지 교수는 이것이 소의 질병인 광우병 잠복기가 사람의 병인 쿠루병보다 훨씬 길 수도 있다는 끔찍한 상황을 암시하고 있다고 지적했다.
쿠루병은 사람에게서 40년 동안이나 잠복할 수도 있으나, 사람에게 감염된 광우병은 이보다 훨씬 긴 기간 잠복해있을 수도 있으며 잠복기는 개인별 유전자 구조에 따라 다를 것이라면서 “이미 진행이 시작된 사례가 훨씬 많을 것이라는게 나는 두렵다”고 말했다.
영국에서는 공식적으로 162명이 인간 광우병으로 사망했다.
과학자들은 100만명당 237건의 발병 가능성에 근거, 영국에서 1만4천명의 인간 광우병 감염자가 나올 수도 있다고 전망하고 있다.
컬린지 교수는 그러나 크로이츠펠트-야콥병을 확인하는 검사기법이 부정확하다면서 이같은 추산치는 “매우 과소평가됐을 수 있다”고 말했다.
김화영 기자 quintet@yna.co.kr (서울=연합뉴스)
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Britain ‘faces CJD epidemic’ from infected beef
By Roger Highfield, Science Editor
Last Updated: 12:01am GMT 10/11/2007
출처 : http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/11/10/scicjd110.xml
The nation faces the possibility of a major epidemic of lethal brain disease as a result of the consumption years ago of beef contaminated with mad cow disease, BSE, according to Britain’s leading expert on vCJD, or “human BSE”.
‘Dramatic’ results of CJD treatment
Prof John Collinge of University College London, a Government advisor, made the comments yesterday when unveiling a new theory of what causes bovine spongiform encephalopathy, Creutzfeldt-Jakob disease and other “neurodegenerative” diseases.
Although the incidence of variant CJD in Britain has been declining, with only four deaths so far this year, Prof John Collinge believes that only people who are genetically susceptible have succumbed to the devastating illness so far. “I continue to be worried,” he told The Daily Telegraph.
Official records show that 162 people have died of vCJD, after a peak of incidence in 2000. But Prof Collinge said that many millions of infectious doses of contaminated beef were eaten between 1980 and 1996 and there is evidence the disease could silently incubate in a person for many decades, without producing symptoms.
In a related human disease called kuru the shortest incubation periods are around five years and he said it was it remarkable that, despite exposure of babies to BSE in contaminated baby food, there has not been any cases in a children younger than 12.
That has the “chilling” implication, he said, that the average incubation period of the cattle disease BSE could be much longer than kuru, which is not surprising because kuru is a human disease.
Given that kuru can incubate in a person for four decades, he would expect even longer incubation periods of the cattle disease BSE in infected people, depending on a person’s genetic makeup. “I am afraid there are a lot more cases in the pipeline,” said Prof Collinge.
The key issue – the potential number of cases – cannot be estimated from the current number of patients. However, based on a preliminary survey of 12,000 appendix samples scientists would expect around 237 cases per million, which works out to be some 14,000.
Prof Collinge said, however, that because of uncertainties about the tests used to detect the presence of CJD, this “could be a considerable underestimate.”
Prof Collinge made his comments while discussing a new theory he has set out in the journal Science with colleague Anthony Clarke that provides a new insight into how these diseases kill brain cells.
Most diseases, such as those caused by viruses and bacteria, contain genetic materials. But BSE and vCJD are caused by a quite different kind of infectious agent consisting of abnormal proteins. The new theory shows how prions, the mis-shapen proteins responsible for lethal diseases such as BSE and vCJD develop in the brain and kill nerve cells.
Earlier work placed emphasis on how abnormal prions convert normal prion protein in the brain to form damaging lumps of mis-shapen protein, called amyloid, in a kind of molecular domino effect. However Prof Collinge provides evidence that this rogue protein itself does not damage the brain directly.
His new theory focuses on how the abnormal proteins link together and identifies smaller clumps of the abnormal proteins as the ones that kill brain cells, not the relatively huge amyloid deposits seen in the brain. These small toxic molecules represent “the missing piece of the puzzle,” Prof Collinge said yesterday.
The work is striking because it suggests that other attempts to find drugs that treat the disease by smashing up the amyloid clumps of abnormal protein could produce the smaller, more lethal variety. “Hitting that is not the thing to do.”
His team, with the backing of GlaxoSmithKline, is working on drugs that, in lab tests, could stop the toxic form of abnormal prion from being made in the first place. Although this effort is still at the level of basic research, “so far so good,” he said.
This drug development work has wider implications, since other degenerative diseases, such as Parkinson’s and Alzheimer’s, are thought to be caused by similar mechanisms.
Thus if this approach can be used to treat CJD, it could work in these other diseases, which are much more common: around 120,000 people in the UK have Parkinson’s and another 700,000 have dementia.
The theory also explains some scientific puzzles, not least how abnormally-shaped proteins can spread from one species to another, crossing the so-called “species barrier,” and how they form different strains of the disease.
“This way of thinking can in principle explain all these different phenomena,” said Prof Collinge.
“This is a fundamental change of thinking and this model fits every piece of data we have got. Of course, now it is the job of other scientists to try to falsify this idea.”
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Scientist preducts future mad-cow epidemic
출처 : http://www.upi.com/NewsTrack/Top_News/2007/11/10/scientist_preducts_future_mad-cow_epidemic/8731/
Published: Nov. 10, 2007 at 5:58 PM
LONDON, Nov. 10 (UPI) — A British scientist predicts thousands of future deaths from mad cow disease caused by contaminated beef eaten between 1980 and 1986.
John Collinge of University College in London said that bovine spongiform encephalopathy and variant Cruzfeldt-Jakob disease, the human version of the disease, appear to have a long incubation period that could stretch to decades in some people, The Telegraph reported. He said BSE has not been seen in anyone younger than 12 even though a lot of children ate contaminated baby food as infants.
“I am afraid there are a lot more cases in the pipeline,” he said.
BSE and related diseases are caused by prions, misshapen proteins.
Collinge has developed a new theory on how the disease becomes lethal. Researchers in the past believed the problem was the large clumps of misshapen cells that form in the brain, but Collinge thinks the lethal work may be done by smaller groups of protein.