Cardiomyopathy Syndrome (CMS)

Cardiomyopathy Syndrome (CMS) is a severe viral disease affecting farmed Atlantic salmon (Salmo salar). It is caused by the Piscine myocarditis virus (PMCV), leading to inflammation and necrosis of the heart muscle. First identified in Norway in the late 1980s, CMS has since been reported in other major salmon farming regions, including Scotland, the Faroe Islands, and Canada, causing significant economic losses 123. CMS primarily affects Atlantic salmon but can also impact other salmonids, such as rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta).

• Physical Signs:

  • Cardiac Lesions: Inflammation and necrosis of the heart muscle, often visible as white or pale streaks.
  • Anemia: Pale gills and organs due to reduced red blood cells.
  • Ascites: Accumulation of fluid in the abdominal cavity.
  • Exophthalmia: Bulging eyes can be observed in affected fish.
• Behavioral Changes:

  • Lethargy: Reduced activity and swimming stamina.
  • Loss of Appetite: Decreased feeding behavior and subsequent weight loss.
  • Abnormal Swimming Patterns: Fish may display erratic or weakened swimming due to cardiac damage 34.

Progression of Symptoms

• Early Stages: Subtle signs such as reduced feed intake and slight lethargy.

• Advanced Stages: More pronounced physical symptoms, including cardiac lesions and anemia, leading to increased mortality if not managed.

• Impact on Fish Health: CMS severely compromises heart function, making fish more susceptible to secondary infections and reducing overall vitality 14.

Etiology

• Causative Agent: Piscine myocarditis virus (PMCV).

• Transmission Methods:

  • Direct Contact: Spread between infected and healthy fish through close proximity.
  • Waterborne: The virus can be transmitted through water, potentially spreading from one farm to another 12.

Risk Factors

• Environmental Factors: Poor water quality, high stocking densities, and stressful conditions can increase susceptibility to CMS.

• Farm Management Practices: Ineffective biosecurity measures and lack of routine health monitoring can facilitate the spread of PMCV 13.

Diagnostic Methods

• Clinical Examination: Observation of physical and behavioral symptoms indicative of CMS.

• Laboratory Tests:

  • PCR (Polymerase Chain Reaction): Detects PMCV genetic material in fish tissues.
  • Histopathology: Microscopic examination of heart tissues to identify characteristic lesions of CMS.
  • Immunohistochemistry: Detects viral antigens in tissue samples 245.

Differential Diagnosis

• Distinguishing CMS from Other Diseases: It is crucial to differentiate CMS from other diseases with similar symptoms, such as Heart and Skeletal Muscle Inflammation (HSMI) and Pancreas Disease (PD) 4.

Treatment Options

• Current Treatments: There are no effective antiviral treatments available for CMS. Management focuses on preventing the spread and mitigating the impact through biosecurity measures and supportive care.

• Experimental Treatments: Ongoing research into potential antiviral agents and other therapeutic approaches 23.

Preventive Measures

• Biosecurity Protocols:

  • Implementing strict quarantine measures for new stock to prevent the introduction of PMCV.
  • Regular disinfection of equipment and facilities to minimize the risk of contamination.
• Farm Management Practices:

  • Reducing stocking densities to decrease the risk of virus transmission.
  • Regular health monitoring and early detection programs to identify and manage outbreaks promptly.
  • Implementing all-in/all-out stocking practices to reduce the risk of spreading infections 123.

**Real-World Examples

• Notable Outbreaks:
  • Norway (1980s): The first identified outbreaks led to significant economic losses and increased regulatory scrutiny.
  • Scotland: Ongoing challenges with managing CMS in salmon farming operations.
  • Canada: Reports of CMS have prompted industry-wide efforts to improve biosecurity and disease management 1234.

1. "Epidemiologisk studie av Kardiomyopatisyndrom (CMS): Spredning, risikofaktorer og sykdomsforløp i norsk lakseoppdrett (CMS-Epi)"
   Authors: Camilla Fritsvold, et al.
   Reference: Norwegian University of Life Sciences (NMBU) study, (2022).
   Link to article
2. "Cardiomyopathy syndrome in Atlantic salmon Salmo salar L.: A review of the current state of knowledge"
   Authors: Å H Garseth, C Fritsvold, J C Svendsen, B Bang Jensen, A B Mikalsen
   Reference: Å H Garseth, et. al. J Fish Dis. 2018. 41(1),11-26.
   Link to article
3. "Persistent immune responses in the heart determine the outcome of cardiomyopathy syndrome in Atlantic salmon (Salmo salar)"
   Authors: Baojian Sun, Marco A. Vindas, Simona Kavaliaskiene, Håvard Bjørgen, Erling Olaf Koppang, Helene Wisløff, Michael Frisk, Hege Lund, Ida B. Johansen
   Reference: Baojian Sun, et. al. Science Direct. 2024. Volume 147.
   Link to article

These studies represent advancements in understanding the prevalence, transmission, and impact of Cardiomyopathy Syndrome (CMS) in salmon farming, particularly in Norway and other European countries with significant salmon farming industries.

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Last Modified: 2024-08-15

Tags: #CardiomyopathySyndrome, #CMS, #Salmonoids, #Salmon, #AtlanticSalmon, #Trout, #RainbowTrout, #BrownTrout, #Piscinemyocarditisvirus, #PMCV, #Norway, #Scotland, #Canada, #FaroeIslands, #ViralDisease, #Virus