Central Veterinary Institute of Wageningen UR, PO Box 65, 8200 AB Lelystad, The Netherlands.
Prev Vet Med. 2012 Sep 15;106(2):108-22. doi: 10.1016/j.prevetmed.2012.01.019. Epub 2012 Feb 15.
African horse sickness (AHS) is a vector-borne viral disease of equines that is transmitted by Culicoides spp. and can have severe consequences for the horse industry in affected territories. A study was performed to assess the risk of introducing AHS virus (AHSV) into the Netherlands (P_AHS) by international equine movements. The goal of this study was to provide more insight into (a) the regions and equine species that contribute most to this risk, (b) the seasonal variation in this risk, and (c) the effectiveness of measures to prevent introduction of AHSV. Countries worldwide were grouped into three risk regions: (1) high risk, i.e., those countries in which the virus is presumed to circulate, (2) low risk, i.e., those countries that have experienced outbreaks of AHS in the past and/or where the main vector of AHS, Culicoides imicola, is present, and (3) very low risk, i.e., all other countries. A risk model was constructed estimating P_AHS taking into account the probability of release of AHSV in the Netherlands and the probability that local vectors will subsequently transmit the virus to local hosts. Model calculations indicated that P_AHS is very low with a median value of 5.1×10(-4)/year. The risk is highest in July and August, while equine movements in the period October till March pose a negligible risk. High and low risk regions contribute most to P_AHS with 31% and 53%, respectively. Importations of donkeys and zebras constitute the highest risk of AHSV release from high risk regions, while international movements of competition horses constitute the highest risk of AHSV release from low and very low risk regions. Preventive measures currently applied reduce P_AHS by 46% if compared to a situation in which no preventive measures are applied. A prolonged and more effective quarantine period in high risk regions and more stringent import regulations for low risk regions could further reduce P_AHS. Large uncertainty was involved in estimating model input parameters. Sensitivity analysis indicated that uncertainty about the probability of non-notified presence of AHS in low and very low risk regions, the protective effect of quarantine and the vector-host ratio had most impact on the estimated risk. Furthermore, temperature values at the time of release of AHSV largely influenced the probability of onward spread of the virus by local vectors to local hosts.
非洲马瘟（AHS）是一种由库蠓属传播的马属动物的虫媒病毒病，在受影响地区会对马业造成严重后果。本研究旨在评估国际马属动物运动将 AHS 病毒（AHSV）引入荷兰（P_AHS）的风险。本研究的目的是提供更多关于（a）对这种风险贡献最大的地区和马属动物，（b）这种风险的季节性变化，以及（c）预防 AHSV 引入措施的有效性的见解。世界各国被分为三个风险区：（1）高风险，即病毒被认为在这些国家传播的国家，（2）低风险，即过去发生过 AHS 暴发的国家和/或 AHS 的主要媒介库蠓属昆虫在这些国家存在的国家，（3）极低风险，即所有其他国家。构建了一个风险模型，该模型考虑了 AHSV 在荷兰释放的概率以及当地媒介随后将病毒传播给当地宿主的概率，从而估算了 P_AHS。模型计算表明，P_AHS 非常低，中值为 5.1×10(-4)/年。风险最高的是 7 月和 8 月，而 10 月至 3 月期间的马属动物运动则带来了微不足道的风险。高风险和低风险地区对 P_AHS 的贡献最大，分别为 31%和 53%。从高风险地区进口驴和斑马构成了 AHSV 释放的最高风险，而从低风险和极低风险地区进口竞技马则构成了 AHSV 释放的最高风险。与未采取预防措施的情况相比，目前实施的预防措施可将 P_AHS 降低 46%。在高风险地区延长和更有效的检疫期以及对低风险地区实施更严格的进口规定，可进一步降低 P_AHS。在估算模型输入参数时存在很大的不确定性。敏感性分析表明，对低风险和极低风险地区 AHS 非通报存在的概率、检疫的保护作用以及媒介-宿主比例的不确定性对估计风险的影响最大。此外，AHSV 释放时的温度值极大地影响了当地媒介向当地宿主传播病毒的可能性。
