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Variant Creutzfeldt-Jakob disease克雅氏病 [size=0.9em]Fact sheet N°180
Revised February 2012
Epidemiology Before the identification of vCJD, Creutzfeldt-Jakob disease (CJD), the most common of the known human TSEs, was thought to exist in only three forms:
- sporadic CJD, which occurs throughout the world at the rate of about one per million people, and accounts for about 85% of CJD cases;
- familial CJD, which is associated with a gene mutation and makes up 5–15% of CJD cases; and
- iatrogenic CJD, which results from accidental transmission via contaminated surgical equipment or as a result of corneal or meningeal (dura mater) transplants or the administration of human-derived pituitary growth hormones; this accounts for less than 5% of CJD cases.
In contrast to the traditional forms of CJD, vCJD has affected younger patients (median age at death of 28 years, as opposed to 68 years) and has a relatively longer duration of illness (median of 14 months as opposed to 4.5 months). The first person to develop symptoms of what turned out to be vCJD became ill in 1994. Most people who have developed vCJD lived in the United Kingdom. Some cases that were diagnosed in countries other than the United Kingdom occurred in people who were probably exposed to the BSE while residing in the United Kingdom. As of early May 2011, the CJD surveillance unit for the United Kingdom reported 172 primary cases of vCJD, and three secondary cases of vCJD related to blood transfusion. Among primary cases, there are four additional cases in the United Kingdom and one in Canada where vCJD is strongly suspected, but the diagnosis has not yet been definitively confirmed by post mortem analysis. Probable cause The nature of the vCJD agent is being investigated and is still a matter of debate. One prevalent theory is that the agent is composed largely, if not entirely, of a self-replicating misfolded protein, referred to as a prion. There is strong scientific evidence that vCJD is linked with exposure to a TSE of cattle called BSE. The link between vCJD and BSE was first hypothesized because of the association of these two TSEs in time and place. In addition, laboratory evidence indicates that vCJD is linked causally with BSE. Intensive surveillance in European countries has confirmed the high incidence of vCJD in the United Kingdom, the country with the largest potential exposure to BSE. Several cases in other countries were likely exposed to the BSE agent while residing in the United Kingdom. The most likely cause of vCJD is exposure to the BSE agent through consumption of food from bovine origin most plausibly contaminated by infected bovine brain or other central nervous system tissue. Only four cases of vCJD infection have been associated with blood transfusion: three of these cases developed symptoms of vCJD several years after transfusion, and one died from unrelated causes before developing symptoms of vCJD, but was shown to be infected with vCJD. 目前对于 prion,我国最新发布的《医疗机构消毒技术规范》翻译为朊病毒。但看目前WHO网站上仍然没有明确说prion是一种病毒,而是说一种流行的理论是,这种因子主要但不完整由一种可以自我复制的错误折叠的蛋白质组成,简称prion。(One prevalent theory is that the agent is composed largely, if not entirely, of a self-replicating misfolded protein, referred to as a prion.)究竟是不是一种病毒呢?还是一种感染性蛋白质?欢迎大家提供证据参与讨论! |