National Veterinary Institute, Pb 750 Sentrum, 0106 Oslo, Norway.
Prev Vet Med. 2013 Aug 1;111(1-2):165-75. doi: 10.1016/j.prevetmed.2013.03.015. Epub 2013 Apr 28.
The decline of fisheries over recent decades and a growing human population has coincided with an increase in aquaculture production. As farmed fish densities increase, so have their rates of infectious diseases, as predicted by the theory of density-dependent disease transmission. One of the pathogen that has increased with the growth of salmon farming is sea lice. Effective management of this pathogen requires an understanding of the spatial scale of transmission. We used a two-part multi-scale model to account for the zero-inflated data observed in weekly sea lice abundance levels on rainbow trout and Atlantic salmon farms in Chile, and to assess internal (farm) and external (regional) sources of sea lice infection. We observed that the level of juvenile sea lice was higher on farms that were closer to processing plants with fish holding facilities. Further, evidence for sea lice exposure from the surrounding area was supported by a strong positive correlation between the level of juvenile sea lice on a farm and the number of gravid females on neighboring farms within 30 km two weeks prior. The relationship between external sources of sea lice from neighboring farms and juvenile sea lice on a farm was one of the strongest detected in our multivariable model. Our findings suggest that the management of sea lice should be coordinated between farms and should include all farms and processing plants with holding facilities within a relatively large geographic area. Understanding the contribution of pathogens on a farm from different sources is an important step in developing effective control strategies.
近几十年来，渔业的衰退和人口的增长与水产养殖产量的增加相吻合。随着养殖鱼类密度的增加，其传染病的发病率也随之增加，这是密度依赖疾病传播理论所预测的。随着鲑鱼养殖业的发展，病原体之一海虱的数量也有所增加。有效管理这种病原体需要了解其传播的空间尺度。我们使用两部分多尺度模型来解释在智利虹鳟鱼和大西洋鲑鱼养殖场每周观察到的海虱丰度的零膨胀数据，并评估内部（养殖场）和外部（区域）海虱感染源。我们观察到，靠近有鱼类暂养设施的加工厂的养殖场，幼体海虱的数量更高。此外，在两周前的 30 公里范围内，养殖场内幼体海虱的数量与临近养殖场内怀孕雌虱的数量之间存在很强的正相关关系，这表明养殖场周围存在海虱暴露的证据。来自临近养殖场的外部海虱源与养殖场内幼体海虱之间的关系是我们多变量模型中检测到的最强关系之一。我们的研究结果表明，海虱的管理应该在农场之间进行协调，并且应该包括在相对较大的地理区域内的所有农场和有暂养设施的加工厂。了解来自不同来源的农场病原体的贡献是制定有效控制策略的重要步骤。
