The epidemiology of pancreas disease in salmonid aquaculture: a summary of the current state of knowledge

Abstract

Pancreas disease (PD) is a viral disease caused by Salmonid alphavirus (SAV) that affects farmed Atlantic salmon (Salmo salar L.) and rainbow trout (Oncorhynchus mykiss (Walbaum)) in the seawater phase. Since its first description in Scotland in 1976, a large number of studies have been conducted relating to the disease itself and to factors contributing to agent spread and disease occurrence. This paper summarizes the currently available, scientific information on the epidemiology of PD and its associated mitigation and control measures. Available literature shows infected farmed salmonids to be the main reservoir of SAV. Transmission between seawater sites occurs mainly passively by water currents or actively through human activity coupled with inadequate biosecurity measures. All available information suggests that the current fallowing procedures are adequate to prevent agent survival within the environment through the fallowing period and thus that a repeated disease outbreak at the same site is due to a new agent introduction. There has been no scientific evaluation of currently used on-site biosecurity measures, and there is limited information on the impact of available mitigation measures and control strategies.

Infection experiments with novel Piscine orthoreovirus from rainbow trout (Oncorhynchus mykiss) in salmonids

“…Furthermore, several viral diseases have been found to transmit between Atlantic salmon and rainbow trout [11,12]. Since the disease outbreaks occurred in Norway where Atlantic salmon is farmed intensively, and in some areas in the same fiords as farmed rainbow trout, investigating if Atlantic salmon are susceptible to the virus is also relevant.…”

Applicability of a food chain analysis on aquaculture of Atlantic salmon to identify and monitor vulnerabilities and drivers of change for the identification of emerging risks

“…PD is listed by OIE from 2014 (http://www.oie.int/en/for-the-media/press-releases/detail/article/newoie-international-standards-and-guidelines-on-animal-health/), possibly because it is a serious problem in Norway and has economic implications for Norwegian salmon farming. According to a recent publication by Jansen et al (Jansen et al, 2017), as a result of the OIE listing any SAV-free country may refuse to import salmon products from areas that have not been declared SAV-free regardless of existing free trade agreements. This may result in additional economic losses for producers.…”

“…This may result in additional economic losses for producers. No scientific information is available on the level of risk associated with the export of SAV-infected whole or filleted salmon (fresh or frozen) to countries or areas that are free from SAV (Jansen et al, 2017).…”

Isolation of salmonid alphavirus subtype 6 from wild‐caught ballan wrasse, Labrus bergylta (Ascanius)

“…Alphaviruses (family Togaviridae ) are a diverse group of small, spherical, enveloped viruses with single‐stranded, positive‐sense RNA genomes (Powers et al., ; Forrester et al., ). Pancreas disease, a major viral disease of farmed Atlantic salmon, Salmo salar (L.) and rainbow trout, Oncorhynchus mykiss (Walbaum) in Europe (McLoughlin & Graham, ; Jansen et al., ), is caused by the salmon pancreas disease virus (SPDV), commonly referred to as the salmonid alphavirus (SAV; Weston et al., ). Pancreas disease has been a significant disease of farmed Atlantic salmon in both Ireland and Scotland since the 1980s (McVicar, ; Murphy et al., ), but the virus was not isolated and characterized until the mid‐1990s, from pancreas disease‐affected Atlantic salmon from the west coast of Ireland (Nelson, McLoughlin, Rowley, Platten, & McCormick, ; Weston, Welsh, McLoughlin, & Todd, ).…”