Ortiz-Peláez A, Arnold M E, Vidal-Diez A
Department of Epidemiological Sciences, Animal and Plant Health Agency,New Haw,Addlestone,Surrey,UK.
Population Health Research Institute, St Georgés University of London,Tooting,London,UK.
Epidemiol Infect. 2016 Jul;144(10):2107-16. doi: 10.1017/S0950268816000303. Epub 2016 Mar 15.
Multiple cases of atypical scrapie in the same holding and co-existence with classical scrapie have been reported in Great Britain. A two-stage simulation tool was developed by combining a sampling algorithm and a hierarchical Bayesian model to simulate the number of positive cases of atypical scrapie from: (i) random sampling and (ii) using the actual sampled population in Great Britain, being the output probability of detection of flocks with one and more cases. Cluster analysis was conducted to assess the level of geographical over- and under-sampling over the years. The probability of detecting at least two cases of atypical scrapie in the same holding is much lower in simulated random data than in simulated actual data for all scenarios. Sampling bias in the selection of sheep for testing led to multiple sampling from fewer but larger holdings, Scotland, and areas of Wales were under-sampled and the South-West and East of England oversampled. The pattern of atypical scrapie cases observed is unlikely to be explained by a multi-case event epidemiologically linked. The co-existence of classical and atypical scrapie is a rare event with 19 holdings detected in GB and does not suggest an epidemiological link between the two types of disease.
在英国，同一养殖场出现多例非典型痒病病例且与经典痒病共存的情况已有报道。通过结合采样算法和分层贝叶斯模型，开发了一种两阶段模拟工具，用于模拟非典型痒病阳性病例数，具体如下：(i) 随机抽样；(ii) 使用英国实际抽样种群，得出检测出有一例及以上病例的养殖场的检出概率。进行聚类分析以评估多年来地理抽样过多和过少的情况。在所有情景下，模拟随机数据中检测到同一养殖场至少两例非典型痒病病例的概率远低于模拟实际数据。在选择用于检测的绵羊时存在抽样偏差，导致对较少但规模较大的养殖场进行多次抽样，苏格兰和威尔士部分地区抽样不足，而英格兰西南部和东部抽样过多。观察到的非典型痒病病例模式不太可能用流行病学关联的多病例事件来解释。经典痒病和非典型痒病的共存是一种罕见事件，在英国检测到19个养殖场出现这种情况，这并不表明这两种疾病之间存在流行病学关联。
