(8.1)--2.6.5我不想吃羊-疯牛病.pdf

微生物 感染与健康 Microbial infection Health 微故事：我不想吃羊 --疯牛病 什么是疯牛病 牛海绵状脑病 ( Bovine Spongiform Encephalitis，BSE) 病原—朊粒 Proteinaceous infectious particle 结构变异的蛋白质 Prion 没有核酸， 比已知的最小病毒小 对蛋白酶K有抗性 病原—朊粒 病原—朊粒 具有复制能力和 免疫原性低，不能刺 传染性 激宿主产生特异性免 疫应答 导致慢性、进行性、 致死性中枢神经系统 无疫苗、无治疗药物 变性脑病 历史 1986 First confirmed case in United Kingdom 1988 U.K. bans meat and bone meal from ruminants in cattle feed 1989 USDA bans importation of ruminants from countries with BSE 历史 1993 Peak of BSE in U.K The epidemic reached a peak in 1992/3 when there were 100,000 confirmed cases. In total, its estimated 180,000 cattle were affected. 经济损失 United Kingdom £3.7 billion total by end of 2001-02 Prior to 1996 £288 million on research, surveillance, compensation In 1996-97 £850 million for compensation Very costly, far reaching disease 地域分布与播散 95% of all BSE cases in U.K 2001 First indigenous case, Japan 2003 First indigenous case, Canada 2005 First indigenous case, U.S.A 传播途径 1 疯牛病是如何传染给牛群的 2 能否在牛群体内传播 3 能否从牛群中传染给其他种属的动物包括人类 传播途径 Humans consuming cattle products infected with BSE can develop vCJD Dose required unknown Genetic susceptibility All human cases have been homozygous for methionine at codon 129 of PrPC Possible modes Eating food contaminated