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Prev Vet Med. 2014 Nov 1;117(1):276-85. doi: 10.1016/j.prevetmed.2014.08.017. Epub 2014 Sep 11.

Risk factors perceived predictive of ISA spread in Chile: applications to decision support.

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USDA APHIS VS Centers for Epidemiology and Animal Health, National Surveillance Unit, 2150 Centre Avenue, Fort Collins, CO 80526-8117, United States. Electronic address:
USDA APHIS VS Centers for Epidemiology and Animal Health, National Surveillance Unit, 2150 Centre Avenue, Fort Collins, CO 80526-8117, United States.
Sernapesca, Chile's National Fisheries and Aquaculture Service, Victoria 2832, Valparaiso, Chile.
SalmonChile, Department of Fish Health, Instituto Tecnologico del Salmon, Av. Juan Soler Manfredini 41, OF 1802 Puerto Montt, Chile.
Marine Harvest Chile, Ruta 226 Km 8 Puerto Montt Chile & Aquaculture Sciences Ph.D Program, Universidad Austral de Chile, PO Box 1327, Puerto Montt, Chile.
Lab de Biotecnología y Patología Acuática Facultad de Ciencias Veterinarias Universidad Austral de Chile Campus Isla Teja s/n, Valdivia, Chile.
Salmones Camanchaca, Diego Portales 2000, Piso 13, Puerto Montt, Chile.
FAV, S.A., A. Pinto 201, Puerto Montt, Chile.
Chile Ltda ADL Diagnostic, Diagnostic Laboratory and Biotechnology, Sector Rod s/n Larch Way, Puerto Montt, Chile.
Plancton Andino Ltda., Terraplen N 869, Puerto Varas, Chile.
Centro de Investigaciones Biologicas Aplicadas (CIBA), Diego de Almagro Norte 1013, Puerto Montt, Chile; Universidad San Sebastian, Facultad de Veterinaria, Lago Panguipulli 1390, Pelluco Alto, Puerto Montt, Chile.


Aquaculture is anticipated to be a critical element in future solutions to global food shortage. However, diseases can impede industry efficiency and sustainability. Consequently, diseases can and have led to dramatic re-structuring in industry or regulatory practices. The emergence of infectious salmon anemia (ISA) in Chile is one such example. As in other countries, many mitigations were instituted universally, and many incurred considerable costs as they introduced a new layer of coordination of farming activities of marine sites within common geographic areas (termed 'neighborhoods' or 'barrios'). The aggregate response led to a strong reduction in ISA incidence and impact. However, the relative value of individual mitigations is less clear, especially where response policies were universally applied and retrospective analyses are missing 'controls' (i.e., areas where a mitigation was not applied). Further, re-focusing policies around disease prevention following resolution of an outbreak is important to renew sustainable production; though, again, field data to guide this shift in purpose are often lacking. Expert panels can offer timely decision support in the absence of empirical data. We convened a panel of fish health experts to weight risk factors predictive of ISA virus (ISAV) introduction or spread between Atlantic salmon barrios in Chile. Barrios, rather than sites, were the unit of interest because many of the new mitigations operate at this level and few available studies examine their efficacy. Panelists identified barrio processing plant biosecurity, fallowing strategies, adult live fish transfers, fish and site density, smolt quality, hydrographic connection with other neighborhoods, presence of sea lice (Caligus rogercresseyi), and harvest vessel biosecurity as factors with the greatest predictive strength for ISAV virulent genotype ('HPR-deleted') occurrence. Fewer factors were considered predictive of ISAV HPR0 genotype ('HPR0') occurrence, with greatest strengths assigned to fish and site density, adult live fish transfers, and smolt facility HPR0 status. Field validation based on ISAV and risk factor occurrence after panel completion generally supports expert estimates, and highlights a few factors (e.g., broodstock HPR0 status) less conclusive in the original study. Results inform legislation, industry best management practices and surveillance design.


Decision support; Expert opinion; Infectious salmon anemia; Risk-based surveillance

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