Pascual-Linaza Ana V, Martínez-López Beatriz, Pfeiffer Dirk U, Moreno José Carlos, Sanz Cristina, Sánchez-Vizcaíno José Manuel
Veterinary Service, Department of Agriculture and Rural Development, Northern Ireland, UK.
Center for Animal Disease Modeling and Surveillance, VM: Medicine and Epidemiology, UC Davis, CA, USA; VISAVET Health Surveillance Centre, Universidad Complutense, Madrid, Spain.
Prev Vet Med. 2014 Oct 1;116(3):279-95. doi: 10.1016/j.prevetmed.2014.05.009. Epub 2014 Jun 2.
Extremadura has been one of the regions in Spain most severely affected by Bluetongue (BT) epidemics. The first incursion of BTV, which was successfully eradicated one year later, occurred in 2004, involving the BTV-serotype 4. However, a second incursion occurred in September 2007, this time involving serotype 1. Since then, the implementation of intensive vaccination programs have significantly reduced BTV-1 occurrence, but the disease has not been completely eradicated yet. This study aimed to provide, for the first time, a complete description of the spatial and temporal patterns of BTV-1 occurrence in sheep in Extremadura from 2007 to 2011 and to identify the risk factors that contributed to the seasonal occurrence of BTV-1 in this region. The results showed that risk factors contributing to BTV-1 occurrence in sheep changed between 2007 and 2011. Initially, when the population was still immunologically naïve, the main risk factors for BTV-1 occurrence were extensive management practices, large sheep farms and Culicoides abundance on farms. However, after the implementation of vaccination, other factors became more relevant for BTV-1 occurrence, mostly related to BTV reservoirs, such as the proximity of cattle farms or the introduction of cattle into farms. The Talaverana sheep breed also seemed to be associated with a significantly higher risk of BTV-1 occurrence, although it may be due to confounding factors, such as the geographical concentration of where this breed is kept and/or management practises used for this breed. The results of this study suggest that preventive and control strategies, including vaccination and active surveillance strategies, should be primarily focused on cattle farms kept in close vicinity to sheep flocks as well as in high-risk sheep farms (i.e. farms with a large farm size keeping both cattle and sheep and with a high number of animal introductions). Methods and results presented here may be used to guide decisions for the annual update of the control and eradication program in Spain.
埃斯特雷马杜拉是西班牙受蓝舌病（BT）疫情影响最严重的地区之一。2004年首次出现蓝舌病毒（BTV），一年后成功根除，涉及BTV血清型4。然而，2007年9月再次出现疫情，这次涉及血清型1。从那时起，强化疫苗接种计划的实施显著减少了BTV-1的发生，但该疾病尚未完全根除。本研究旨在首次全面描述2007年至2011年埃斯特雷马杜拉地区绵羊中BTV-1发生的时空模式，并确定导致该地区BTV-1季节性发生的风险因素。结果表明，2007年至2011年期间，导致绵羊发生BTV-1的风险因素发生了变化。最初，当种群仍处于免疫未接触状态时，BTV-1发生的主要风险因素是粗放的管理方式、大型养羊场和农场库蠓数量。然而，实施疫苗接种后，其他因素对BTV-1的发生变得更加重要，主要与BTV宿主有关，如养牛场的距离或牛引入农场。塔拉韦拉绵羊品种似乎也与BTV-1发生的风险显著较高有关，尽管这可能是由于混杂因素，如该品种饲养的地理集中程度和/或用于该品种的管理方式。本研究结果表明，包括疫苗接种和主动监测策略在内的预防和控制策略应主要针对与羊群紧邻的养牛场以及高风险养羊场（即养殖规模大且同时饲养牛和羊且动物引入数量多的农场）。此处介绍的方法和结果可用于指导西班牙控制和根除计划年度更新的决策。
