Abstract Salmonid rickettsial septicaemia (SRS) is the most important disease of farmed salmonid fish in Chile and the main driver of a high rate of antimicrobial use. This study evaluated the effectiveness of antimicrobial treatment of SRS outbreaks, using industry-generated data from 8318 cage-level production cycles stocked between 2003 and 2018. We defined SRS outbreaks by a specified level of SRS-attributed mortality over a 3-week period and calculated the mortality rate attributed to SRS and unknown causes during a follow-up period from the start of treatment until resolution of the outbreak. The post-treatment mortality rate was used as a proxy for assessing the effectiveness of the antimicrobial treatment on the magnitude of the SRS outbreak. After developing a causal diagram, we analyzed the data with generalized, mixed-effects regression models within an information-theoretic framework. For producers of Atlantic salmon, our results suggest that treatment should be provided to all infected cages on the farm, without interruption, as soon as possible after the start of the SRS outbreak. For producers of rainbow trout, our results suggest that treatment should be initiated as early as possible after the start of the SRS outbreak and with longer treatment durations if using in-feed florfenicol treatments. In the rainbow trout model, the large proportion of unexplained variance at the company and farm level indicates that lessons can be learned from the experience of other companies and farms. This study demonstrates the value of integrating aquaculture industry-generated health and management data to support applied epidemiological research.

中文翻译：

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智利商业鲑鱼和鳟鱼养殖场鲑鱼立克次体败血症的抗菌治疗效果

摘要 三文鱼立克次体败血症（SRS）是智利养殖三文鱼最重要的疾病，也是抗生素使用率高的主要驱动因素。本研究使用来自 2003 年至 2018 年间储存的 8318 个网箱级生产周期的行业生成数据评估了抗生素治疗对 SRS 暴发的有效性。我们通过 3 周内特定的 SRS 归因死亡率水平来定义 SRS 暴发，并且计算了从治疗开始到爆发解决的随访期间归因于 SRS 和不明原因的死亡率。治疗后死亡率被用作评估抗菌治疗对 SRS 爆发规模的有效性的代理。在绘制因果图后，我们用广义的、信息理论框架内的混合效应回归模型。对于大西洋鲑鱼的生产者，我们的结果表明，应在 SRS 爆发后尽快对养殖场内所有受感染的网箱进行治疗，不得中断。对于虹鳟鱼的生产者，我们的结果表明，在 SRS 爆发后应尽早开始治疗，如果使用饲料中的氟苯尼考治疗，治疗时间应更长。在虹鳟鱼模型中，公司和养殖场层面存在很大比例的无法解释的差异表明可以从其他公司和养殖场的经验中吸取教训。这项研究证明了整合水产养殖业产生的健康和管理数据以支持应用流行病学研究的价值。