Home Disease Challenges Salmon Rickettsial Syndrome (SRS)

Salmon Rickettsial Syndrome (SRS)

Piscirickettsia salmonis

Animal model: Atlantic salmon (Salmo salar L.)

Source of CAT isolates:  

Applications: Vaccines, functional feeds, repellents, physical barriers, environmental treatments, system modification, immersion and in feed treatments, benchmarking commercial treatment efficies, genetic selection/phenotyping

Type of model: Intraperitoneal (IP) injection, cohabitation

Clinical Signs of Disease in our Model: Pale and mottled liver, internal and external petechial haemorrhaging, ulcerative lesions on the skin, and anemia

Challenge conditions: 0-36ppt; 13-16C

Other end points: Semi-quantitative pathological scoring, periodic sampling

Starting Fish Size: 10 - 200 grams


A newly smolted Atlantic salmon, euthanized during SRS challenge, exhibiting a cutaneous skin lesion on left flank.


The bacterium Piscirickettsia salmonis is the aetiological agent of Salmon Rickettsial Syndrome (SRS), or piscirickettsiosis. This organism causes major economic losses in the Chilean salmonid aquaculture industry, particularly in Coho and Atlantic salmon. The geographical range is vast and includes North America and Europe, impacting salmon predominantly in salt water. The proliferation and virulence of P. salmonis are increased at higher water temperatures, making it a pathogen of importance when considering the impacts of climate change and its effects on aquaculture sustainability. Prolonged periods of high sea water temperatures are predicted to occur which could extend the impacts of SRS on the Chilean industries and increase impacts on North American and European operations. Antibiotics and vaccines are the primary control measures used to manage SRS in Chilean aquaculture. Several vaccines have been used with inconsistent results between studies and outbreaks, and prolonged protection from intraperitoneal vaccination is difficult to achieve, even with oral boosts. The inconsistent efficacy of antibiotics is also problematic for the industry. Prevalence of drug-resistant strains to commonly used products such as oxytetracycline, florfenicol, and streptomycin, among others, is common.

Representative survival curve of whiteleg shrimp post challenge with V. parahaemolyticus via per os

Thus, replacement antibiotics, novel vaccine formulations, and other alternative therapies such as immunostimulation by in-feed products, are in high demand. At CAT, in vivo models for testing treatments against P. salmonis have been developed in fresh and salt water for Atlantic salmon parr, pre-smolts, and post-smolts. Trials which address the safety and efficacy of products are customized to mimic on-farm outbreaks and include both intraperitoneal and cohabitation challenge models. An in vitro challenge model using ASK cells infected with P. salmonis is also available for product screening and characterization. Lastly, laboratory services include a variety of analytics, gene expression profiling, determination of bacterial load by qPCR, and biochemical assays in blood and mucous add additional value to both in vitro and in vivo challenges.

We can customize existing models and develop tailored solutions based on your needs