基于Bernoulli分布的全球疯牛病发生风险研究

The Study on the Global BSE Developing Risk Based on Bernoulli Distribution

在数据挖掘基础上,基于地理信息技术(Geographical Information Sciences,GIS),结合概率风险评估的方法和理论探讨在全球尺度上疯牛病的发展风险。结果显示:(1)疯牛病主要发生在畜牧养殖业高度集约化和饲喂工业化发达的国家,全球化和工业化程度的增加将增加全球疯牛病致病因子的扩散和传播的风险。(2)当前国际上牛养殖密度最大的主要区域集中在南亚次大陆的印度、泰国、缅甸和巴基斯坦,以及欧洲南部国家、非洲的埃塞俄比亚以及南美洲等地区。饲养量大、饲喂密集区在给定疯牛病接触风险条件下,暴露风险显著增大。(3)从全球疯牛病发生的历史看,疯牛病在1986年首次确诊,1986-1991年为扩散期,到1992年疯牛病发生和流行达到高峰,达到3.0×10-5的风险概率。在欧盟范围内疯牛病的发病高峰在1992-1993年,1992年BSE发生的流行率为4.28×10-4,1993年欧盟疯牛病流行率为4.13×10-4,1994年疯牛病的流行率降低到2.92×10-4的概率水平,即在1992-1993年期间,欧盟每百万头牛的疯牛病阳性检出数量就达400～500头,可以认为1991-1994年这段时间为欧盟疯牛病发生的极高风险期。在这一阶段内从欧盟输出的反刍动物及产品会给进口国家和地区带来极其显著的BSE外来释放风险。目前国际上疯牛病的风险高值区还主要集中在欧洲地区,包括欧洲的比利时、捷克、丹麦、法国、德国、爱尔兰、意大利、荷兰、波兰、葡萄牙、斯洛伐克、西班牙、瑞士、英国,以及亚洲的日本,这些国家在理论上还可能存在疯牛病潜在病例;次风险区在斯洛文尼亚、加拿大、瑞典、卢森堡、美国等国家,这些国家至少发生1头BSE感染病牛的风险期望值也在0.800 9左右。此外芬兰、希腊的疯牛病发生风险期望值也较大。从疯牛病风险区域和国家输入反刍动物及其产品会给输入国家和地区带来外来释放风险。

The global pattern of Bovine Spongiform Encephalopathy（BSE） risks status was explored and discussed in this article.Based on GIS techniques and the theory of probability risk assessment,the studies on risk assessment of global-scaled BSE status were carried out.The results were as follows：（1） BSE cattle populations mainly existed in the countries that livestock populations were highly industrialized.Trend on increasingly globalization and industrialization can greatly facilitate the dispersion of the release exposure risks of BSE agents around the world.（2） Globally,the high density of cattle inventory were mainly distributed in the subcontinent of southern Asia（included Indian,Thailand,Myanmar and Pakistan）,southern Europe,Ethiopia of Africa and south American region,highly concentration of cattle inventory can make BSE exposure risks dramatically increased in given released BSE risks.（3） From global scale,BSE reached the zenith of its epidemiological spreading in the 1992,in which year BSE prevalence come to be 3.0×10^-5 probability level,mean that there should at least have thirty heads of cattle to be BSE positive among one million randomly selected cattle.In Europe scale,BSE pandemic got its zenith between 1992 to 1993,corresponding prevalence come to be 4.28×10^-4 and 4.13×10^-4 respectively,which mean that there should at least have 400-500 heads of cattle to be BSE positive among one million randomly selected cattle.It could be reasonable assumed that 1992-1993 should be the highest BSE risk period in EU and the world,in which interval,bovine and its bovine related products within EU can bring significant BSE risks to the import region and country outside EU.Currently,the highest BSE risk still exists in EU region,including Belgium,Czechic,Danmark,France,German,Ireland,Italy,Netherlands,Poland,Portugal,Slovak,Spain,Switzerland and UK,and Japan of Asian,all above countries could have new emerged BSE cases theoretically.Second ranked risk region were in Slovenia,Canada,Sweden,Luxemburg and USA,in which countries,the expected BSE risk for at least one head BSE positive cattle to be 0.800 9.Besides,Finland and Greece also have some expected BSE risks in their cattle populations.