Alocilla-Velásquez Oscar, Monti Gustavo, Saatkamp Helmut, Mourits Monique, Lindberg Ann, Widgren Stefan
Department of Veterinary Sciences and Public Health, Natural Resources Faculty, Universidad Católica de Temuco, Temuco, Chile.
Quantitative Veterinary Epidemiology, Wageningen University, Droevendaalsesteeg 1 (Campus) Building No. 107, 6702 PB, Wageningen, Netherlands.
Transbound Emerg Dis. 2024 Oct 28;2024:4734277. doi: 10.1155/2024/4734277. eCollection 2024.
Bovine viral diarrhea (BVD) represents a serious threat to the cattle sector in Chile, indicating the need for a regionally defined control program. evaluations of program options using simulation modeling have proven to be a successful approach in providing decision-makers with relevant supporting insights in that respect. Given the complexity of bovine viral diarrhea virus (BVDV) infection dynamics, simulation of BVD spread in a metapopulation requires detailed consideration of both within and between herd transmission dynamics. The aims of the study are (i) to investigate the dynamics of BVDV transmission in cattle herds in southern Chile by linking a within-herd transmission model (WHM) that accounts for the BVDV's unique characteristics with a between-herd model (BHM) that meets the demands for further regional control strategy evaluation; (ii) to suggest and discuss criteria for evaluation of the model approach and plausibility for later research and for support decision-making. This resulted in bringing forth a modeling rationale for complex disease spread simulation in metapopulations. BHM simulations under this approach show outcomes that agree with BVDV's known situation in Chile; dairy herds prevalence at endemic equilibrium reaches and maintains 75%, which agrees with estimations of BVDV active infection in dairy herds in southern Chile (77%). For the entire herd population, the infection always reaches endemic levels with a large proportion of infected herds (median = 60%), where herd prevalence was higher in the dairy herd class than in the remaining categories. Transmission probability variation affects the new infections picked, prevalence at endemic levels, and the velocity in which the infection spreads between herds. The fact that the presented approach was able to model a complex infection dynamic such BVDV, with sufficient confidence, provides evidence that this approach can be used to explore mitigation strategies to control BVDV in southern Chilean herds.
牛病毒性腹泻（BVD）对智利的养牛业构成严重威胁，这表明需要制定一项区域界定的控制计划。利用模拟模型对计划选项进行评估已被证明是一种成功的方法，能够在这方面为决策者提供相关的支持性见解。鉴于牛病毒性腹泻病毒（BVDV）感染动态的复杂性，在异质种群中模拟BVD的传播需要详细考虑畜群内部和之间的传播动态。本研究的目的是：（i）通过将考虑BVDV独特特征的畜群内部传播模型（WHM）与满足进一步区域控制策略评估需求的畜群间模型（BHM）相联系，研究智利南部牛群中BVDV的传播动态；（ii）提出并讨论评估模型方法的标准以及对后续研究和支持决策的合理性。这带来了一种用于异质种群中复杂疾病传播模拟的建模原理。在这种方法下的BHM模拟结果与智利BVDV的已知情况相符；地方病平衡时奶牛群的患病率达到并维持在75%，这与智利南部奶牛群中BVDV活跃感染的估计值（77%）一致。对于整个牛群，感染总是达到地方病水平，且有很大比例的感染牛群（中位数 = 60%），其中奶牛群类别的畜群患病率高于其他类别。传播概率变化会影响新感染的数量、地方病水平的患病率以及感染在畜群间传播的速度。所提出的方法能够以足够的可信度对诸如BVDV这样的复杂感染动态进行建模，这一事实证明该方法可用于探索控制智利南部牛群中BVDV的缓解策略。
