Animal Health Service, PO Box 9, 7400AA Deventer, The Netherlands.
Prev Vet Med. 2013 Mar 1;108(4):276-84. doi: 10.1016/j.prevetmed.2012.11.004. Epub 2013 Jan 16.
Bluetongue virus serotype 8 (BTV-8) emerged in north-western Europe in 2006. In 2007, one of the affected countries (the Netherlands) implemented a sentinel network in dairy cattle. This data offered the opportunity to estimate transmission parameters. From our field data, the number of secondary infected cows that became infected by one infectious cow in a completely susceptible herd through the bites of infectious Culicoides i.e. the basic reproduction ratio (R(0)) was calculated. With that information, the R(0) of BTV-8 was estimated using an formulae of a general SIR model. In 2007, the BTV-8 epidemic started in the south and spread northwards in the following months. R(0) could be estimated for 197 herds in which transmission occurred. The median R(0) was 2.3 and the mean R(0) was 3.7 (5th percentile=1.8; 95th percentile=11.0). In the northern region where BTV-8 transmission occurred later in the season with less favorable conditions for transmission, R(0) remained significantly lower than in the south. Our model differed from earlier published more theoretical models on BTV-8 transmission because we estimated transmission from serological field data while other models used literature based assumptions for the majority of the parameters included in their models. Although there were many differences between our model and the previously developed more theoretical models, the results showed similar ranges of R(0) for BTV-8. The reasons for the similarity between the results may be that, although the part of the vector was not included with parameters in our model, the transmission based on serological field data in cows represented both BTV-8 transmission influenced by cows and by its vector, Culicoides. Furthermore, in the earlier models the assumptions made on the vector part, although derived from literature, probably gave a good representation of the true behavior of the Culicoides species that were associated with BTV-8 transmission in north-western Europe.
8 型蓝舌病毒（BTV-8）于 2006 年在欧洲西北部出现。2007 年，受影响的国家之一（荷兰）在奶牛中实施了一个监测网络。这些数据提供了估计传播参数的机会。根据我们的实地数据，在一个完全易感的牛群中，一只感染牛通过感染性库蠓的叮咬而感染的继发感染牛的数量，即基本繁殖数（R(0)）被计算出来。有了这些信息，我们使用一般 SIR 模型的公式来估计 BTV-8 的 R(0)。2007 年，BTV-8 疫情从南部开始，并在接下来的几个月向北传播。在发生传播的 197 个牛群中，可以估计 R(0)。中位数 R(0)为 2.3，平均值 R(0)为 3.7（5%分位数=1.8；95%分位数=11.0）。在北部地区，BTV-8 的传播发生在季节较晚的时候，传播条件对传播不利，R(0)仍然明显低于南部地区。我们的模型与之前发表的关于 BTV-8 传播的更理论性的模型不同，因为我们从血清学实地数据中估计传播，而其他模型则使用文献为其模型中包含的大多数参数提供假设。尽管我们的模型与之前开发的更理论性的模型有许多差异，但结果显示 BTV-8 的 R(0)范围相似。结果相似的原因可能是，尽管我们的模型没有包括向量部分及其参数，但基于牛血清学实地数据的传播既代表了 BTV-8 传播受牛的影响，也受库蠓的影响。此外，在早期模型中，对媒介部分的假设，尽管来自文献，但可能很好地代表了与 BTV-8 在西北欧传播相关的库蠓的真实行为。
