Transmission of Piscirickettsia salmonis among salt water salmonid farms in Chile

Rees, Erin E.; Ibarra, R.; Medina, Matías H.; Sánchez, Javier; Jakob, Eva; Vanderstichel, Raphaël; St‐Hilaire, Sophie

doi:10.1016/j.aquaculture.2014.03.031

Cited by 37 publications

(32 citation statements)

References 8 publications

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“…These conditions may have also contributed to the elevated survival in the tank‐reared salmon; however, these fish also benefited from treatment at an earlier stage of the disease outbreak due to the earlier diagnosis in the NP‐reared salmon. The earlier onset and increased SRS‐associated mortality in the NP‐reared salmon held under more variable conditions were similar to that in aquaculture in which outbreaks of the disease have been associated with elevated water temperatures (Rees et al, ), algal blooms and severe meteorological events (Cusack, Groman, & Jones, ; Olsen, Melby, Speilberg, Evensen, & Hastein, ). Infection with multiple pathogens may increase the severity of disease in fish (Long, Garver, & Jones, ); however, there was no evidence of co‐infection or pathology of sufficient intensity or severity to explain the increased mortality in the NP‐reared salmon.…”

Section: Discussionsupporting

confidence: 62%

Factors associated with severity of naturally occurring piscirickettsiosis in netpen‐ and tank‐reared juvenile Atlantic salmon at a research aquarium in western Canada

Jones

Long

MacWilliams

et al. 2019

Journal of Fish Diseases

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The opportunistic examination of factors associated with an outbreak of piscirickettsiosis (SRS) is described in Atlantic salmon Salmo salar post‐smolts held in an open netpen or in tanks supplied with raw sea water at a research aquarium in western Canada. During the outbreak, seawater temperature was significantly higher and salinity significantly lower in the netpen compared with the tanks. Mortality in the netpen began approximately 3 weeks prior to that in the tanks, and cumulative mortality in the netpen (34%) was significantly higher than in the tanks (12%). Piscirickettsia salmonis was confirmed by qPCR in tissues from moribund and dead fish and from colonies grown on enriched blood agar medium. Neither P. salmonis nor SRS were observed in salmon held concurrently in UV‐irradiated sea water. The elevated mortality was curtailed by treatment with oxytetracycline. These observations further indicate warmer, less saline and periodically hypoxic seawater are risk factors for SRS. UV irradiation of sea water is shown to be a tool for SRS management in fish‐holding facilities.

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Section: Discussionsupporting

confidence: 62%

Factors associated with severity of naturally occurring piscirickettsiosis in netpen‐ and tank‐reared juvenile Atlantic salmon at a research aquarium in western Canada

Jones

Long

MacWilliams

et al. 2019

Journal of Fish Diseases

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“…During natural infections, P. salmonis is transmitted horizontally from fish-to-fish without the need for physical contact (31, 32). No vector or intermediate host has been identified (17), and during experimental trials, the pathogen has been observed in the milt and celomic fluid of adult brood fish, and also in fry of infected brood fish, suggesting that the bacterium is transmitted vertically (33).…”

Section: Spread Of Infectionmentioning

confidence: 99%

Immunization Strategies against Piscirickettsia salmonis Infections: Review of Vaccination Approaches and Modalities and Their Associated Immune Response Profiles

Evensen

2016

Front. Immunol.

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Salmonid rickettsial septicemia (SRS) is a serious, infectious disease in Chilean salmon farming caused by Piscirickettsia salmonis, causing heavy losses to the salmonid industry. P. salmonis belongs to the Gammaproteobacteria, order Thiotrichales. SRS was first described in Chile in 1989, and infection with P. salmonis has since been described from a high number of fish species and in several geographic regions globally. P. salmonis infection of salmonids causes multifocal, necrotic areas of internal organs such as liver, kidney, and spleen. Histologically and immunologically, the tissue response is the formation of granulomas, often with central suppuration. The exact sequence of infection is not known, but bacteria likely gain access to internal organs through mucosal surfaces and when infected, fish carry bacteria in macrophages. It has not been fully determined if the bacterium resides in the cytosol or “hide” within vesicular structures intracellularly, although there are indications that in vitro infection results in actin reorganization and formation of actin-coated vesicle within which the bacterium resides. Protection against lethal challenge is well documented in lab scale experiments, but protection from vaccination has proven more difficult to attain long term under field conditions. Current vaccination protocols include whole cell, inactivated and adjuvanted vaccines for injection for primary immunization followed by oral boost where timing of boost delivery is followed by measuring circulating antibody levels against the pathogen. Documentation also exist that there is correlation between antibody titers and protection against mortality. Future vaccination regimes will likely also include live-attenuated vaccines or other technologies such as DNA vaccination. So far, there is no documentation available for live vaccines and, for DNA vaccines, studies have been unsuccessful under laboratory conditions.

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“…For all three salmon species farmed in Chile, the prevalence of SRS in fattening centres is high, but the outbreaks are more severe in rainbow trout (Jakob et al., ). SRS mainly occurs in sea water and estuarine water (Branson & Nieto Díaz‐Muñoz, ; Bravo & Campos, ; Cvitanich et al., ; Fryer et al., ), where its prevalence is associated with water temperature, culture time in the sea, distance and number of neighbouring farms with SRS (Rees et al., ). Economic losses attributed to SRS have been estimated at approximately US $500 million (Rozas & Enríquez, ).…”

Section: Introductionmentioning

confidence: 99%

Comparative pathogenesis of piscirickettsiosis in Atlantic salmon (Salmo salar L.) post‐smolt experimentally challenged with LF‐89‐like and EM‐90‐like Piscirickettsia salmonis isolates

Rozas‐Serri¹,

Ildefonso²,

Peña³

et al. 2017

Journal of Fish Diseases

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Piscirickettsiosis (SRS) is the most prevalent bacterial disease in Chilean salmon aquaculture and is responsible for high economic losses. The aim of this study was to comparatively characterize the pathogenesis of SRS in post-smolt Atlantic salmon during the early and late stages of infection with Piscirickettsia salmonis LF-89-like (PS-LF-89) and EM-90-like (PS-EM-90) using a cohabitation challenge. The pathogenesis of cohabitant fish infected with the two isolates was relatively different due to cohabitant fish infected with PS-EM-90 showing higher cumulative mortality and shorter time until death compared with PS-LF-89 fish. PS-LF-89 caused an SRS infection characterized by kidney and liver lesions, whereas PS-EM-90 caused systemic and haemorrhagic disease characterized by kidney, liver, heart, brain, skeletal muscle and intestine lesions. Decreased serum concentration of total proteins and albumin as well as increased serum ALT, AST and creatinine levels in fish infected with both isolates confirmed that changes in liver and kidney function occurred during infection. Tissue damage, expressed as an SRS histoscore, showed a strong positive correlation with the bacterial load expressed as abundance of P. salmonis 16S rRNA transcripts in the livers and kidneys of fish affected with either isolate, but the correlation was significantly higher in fish infected with PS-EM-90. The results contribute to improving the understanding of the bacteria-host interaction.

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Transmission of Piscirickettsia salmonis among salt water salmonid farms in Chile

Cited by 37 publications

References 8 publications

Factors associated with severity of naturally occurring piscirickettsiosis in netpen‐ and tank‐reared juvenile Atlantic salmon at a research aquarium in western Canada

Factors associated with severity of naturally occurring piscirickettsiosis in netpen‐ and tank‐reared juvenile Atlantic salmon at a research aquarium in western Canada

Immunization Strategies against Piscirickettsia salmonis Infections: Review of Vaccination Approaches and Modalities and Their Associated Immune Response Profiles

Comparative pathogenesis of piscirickettsiosis in Atlantic salmon (Salmo salar L.) post‐smolt experimentally challenged with LF‐89‐like and EM‐90‐like Piscirickettsia salmonis isolates

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