牛海绵状脑病

牛海绵状脑病（ｂｏｖｉｎｅ　ｓｐｏｎｇｉ－ｆｏｒｍ　ｅｎｃｅｐｈａｌｏｐａｔｈｙ， ＢＳＥ），又称“疯牛病”，是一种成年牛致命性神经系统性疾病，是根据当时病畜特殊的变性病变而命名的（ＢＳＥ），它是由一种非常规致病因子引起的一种亚急性海绵状脑病。该病的主要特生是牛脑发生海绵状病变，并伴随大脑功能退化，临床表现为神经质、运动失调、痴呆和死亡。能够表现这种症状的疾病还有羊的痒病、人的库鲁氏病和人的克雅氏病（ＣＪＤ）等。 该病于１９８５年４月在英国阿什福特农场首次发现，１９８６年开始命名为ＢＳＥ。当１９９…     

Transmission dynamics and changing epidemiology of West Nile virus

West Nile virus (WNV) is a flavivirus that is maintained in a bird-mosquito transmission cycle. Humans, horses and other non-avian vertebrates are usually incidental hosts, but evidence is accumulating that this might not always be the case. Historically, WNV has been associated with asymptomatic infections and sporadic disease outbreaks in humans and horses in Africa, Europe, Asia and Australia. However, since 1994, the virus has caused frequent outbreaks of severe neuroinvasive disease in humans and horses in Europe and the Mediterranean Basin. In 1999, WNV underwent a dramatic expansion of its geographic range, and was reported for the first time in the Western Hemisphere during an outbreak of human and equine encephalitis in New York City. The outbreak was accompanied by extensive and unprecedented avian mortality. Since then, WNV has dispersed across the Western Hemisphere and is now found throughout the USA, Canada, Mexico and the Caribbean, and parts of Central and South America. WNV has been responsible for >27,000 human cases, >25,000 equine cases and hundreds of thousands of avian deaths in the USA but, surprisingly, there have been only sparse reports of WNV disease in vertebrates in the Caribbean and Latin America. This review summarizes our current understanding of WNV with particular emphasis on its transmission dynamics and changing epidemiology.     

Pathogenesis of BSE

Before the emergence of bovine spongiform encephalopathy (BSE) and recognition of its zoonotic potential, the major example of the transmissible spongiform encephalopathies (TSEs) of animals was scrapie of sheep. But there is no evidence that scrapie transmits naturally to any species other than sheep and goats. The pathogenesis of scrapie has been studied most in experimental laboratory rodent species. In most experimental models of scrapie, after peripheral non-neural routes of infection, replication of the agent can first be detected in lymphoreticular system (LRS) tissue. When the route of introduction of agent into the body is localized, initial involvement will be in LRS tissue draining the infection site. Thereafter, there is a striking amplification of the agent in the LRS and spread by lymphatic/haematogenous routes, giving widespread dissemination in the LRS. This precedes replication in the CNS, but is not the means by which infection reaches the CNS. There is now substantial evidence from experimental models of scrapie that involvement of the CNS is by peripheral nervous system (PNS) pathways. In some models employing oral exposure the earliest localized LRS replication is in the gut-associated lymphoid tissue (GALT) and autonomic PNS routing to the CNS has been implicated. However, the relative importance of different routes of spread of TSEs within the body is determined by a number of host- and agent-dependent factors and, therefore, generalizations from an experimental model to a natural disease across a species barrier may not be appropriate. With the occurrence of BSE and recognition of its food-borne route of transmission via meat and bone meal, has come greater awareness of the probable importance of the oral route of infection in ruminant species affected by TSEs. In consequence, studies have increasingly focused on the natural host species to examine pathogenetic events.     

疯牛病致病机理研究进展

疯牛病即牛海绵状脑病是一种由朊蛋白感染引起的非炎性的致死性的脑退化性疾病 ,并可传染给人 ,引起人类的新型克雅氏病。疯牛病已经给英国养牛业造成了数百亿美元的直接经济损失 ,并有“东扩”蔓延的趋势 ,已对养牛业发展和人类健康构成巨大威协 ,成为国际兽医学界和医学界关注的热点。疯牛病的致病机理异常独特和复杂。文章对朊蛋白的结构、功能和增殖模式及其致病机理进行了综述 ,并对其研究方向进行了展望。     

Pathogenesis of BSE

Before the emergence of bovine spongiform encephalopathy (BSE) and recognition of its zoonotic potential, the major example of the transmissible spongiform encephalopathies (TSEs) of animals was scrapie of sheep. But there is no evidence that scrapie transmits naturally to any species other than sheep and goats. The pathogenesis of scrapie has been studied most in experimental laboratory rodent species. In most experimental models of scrapie, after peripheral non-neural routes of infection, replication of the agent can first be detected in lymphoreticular system (LRS) tissue. When the route of introduction of agent into the body is localized, initial involvement will be in LRS tissue draining the infection site. Thereafter, there is a striking amplification of the agent in the LRS and spread by lymphatic/haematogenous routes, giving widespread dissemination in the LRS. This precedes replication in the CNS, but is not the means by which infection reaches the CNS. There is now substantial evidence from experimental models of scrapie that involvement of the CNS is by peripheral nervous system (PNS) pathways. In some models employing oral exposure the earliest localized LRS replication is in the gut-associated lymphoid tissue (GALT) and autonomic PNS routing to the CNS has been implicated. However, the relative importance of different routes of spread of TSEs within the body is determined by a number of host- and agent-dependent factors and, therefore, generalizations from an experimental model to a natural disease across a species barrier may not be appropriate. With the occurrence of BSE and recognition of its food-borne route of transmission via meat and bone meal, has come greater awareness of the probable importance of the oral route of infection in ruminant species affected by TSEs. In consequence, studies have increasingly focused on the natural host species to examine pathogenetic events.     

Review article: actual danger to the domestic animal populations of exotic animal epidemics

Most of the formerly important virus diseases like foot-and-mouth disease and enzootic bovine leukosis were eradicated in the Federal Republic of Germany during the recent decades. However, there is a continuous menace of our domestic animal population by exotic virus epidemics related to the concentration of animals in large farms, the intensified international trade of animals and their meat or milk products, and the introduction of a common European market starting in 1992. This view is emphasized by the recent outbreaks of African horse sickness in Spain in 1987/1988. In this article, foot-and-mouth disease and African horse sickness will be described as potentially dangerous virus epidemics. Furthermore, the occurrence of formerly unknown diseases has to be considered. Haemorrhagic disease of rabbits which was recently introduced in Germany is an example of new developments in virus epidemics. These three diseases, their epidemiology and the biology of the corresponding viruses will be discussed in detail.     

Effects of BSE on consumer attitudes and behavior

The extremely high media emphasis of the BSE issue during the period December 2000 to February 2001 has caused considerable short term public concern. A significant amount of this concern was due to an intensive communication of pictures. Pictures are "fast shots into the brain" (Kroeber-Riel). Pictured stimuli run under the cognitive control of the recipients effecting the consumer below the threshold of consciousness. However, the issue has fallen into oblivion very soon. In summer 2001 the public concern was not higher than before the BSE crisis. The perception of product quality regained a "normal level". The public concern has caused a considerable decline of the demand for beef and an increase of demand for substitutes and organic meat. When the media emphasis of the BSE issue diminished, the beef demand recovered but did not reach the pre-crisis level again. However, the BSE crisis has intensified animal welfare concerns, polarized public opinion about food and agriculture and had big effects in the political sphere. Furthermore, the BSE crisis has led to additional--politically supported--activities of the organic food suppliers causing a further growth of this market segment.