Tenacibaculum

Tenacibaculosis is a bacterial disease affecting various fish species in aquaculture, including Atlantic salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss), and marine species such as sea bass (Dicentrarchus labrax) and sea bream (Sparus aurata). It is caused by the bacterium Tenacibaculum maritimum, leading to skin ulcers, fin erosion, and high mortality rates, resulting in significant economic losses. The disease was first identified in Japan in the 1970s and has since been reported in many countries worldwide, including Norway, Chile, and the United States 124.

• Physical Signs:

  • Skin Ulcers: Deep, necrotic ulcers on the skin, often around the mouth, fins, and body.
  • Fin Erosion: Fraying and degradation of the fins, especially the caudal (tail) fin.
  • Hemorrhages: Reddened areas on the skin and fins due to bleeding.
  • Exophthalmia: Bulging or protruding eyes.
  • Necrosis: Tissue death in severe cases, leading to extensive damage.
• Behavioral Changes:

  • Lethargy: Reduced activity and slow swimming.
  • Loss of Appetite: Decreased feeding behavior and significant weight loss.
  • Abnormal Swimming Patterns: Fish may swim erratically or show signs of distress due to pain from ulcers.

Progression of Symptoms

• Early Stages: Small, localized lesions and mild redness around the mouth and fins.
• Advanced Stages: Severe skin ulcers, extensive fin erosion, and high mortality if left untreated.
• Impact on Fish Health: Tenacibaculosis severely compromises the skin barrier, leading to stress, reduced growth rates, and higher susceptibility to secondary infections 12.

Etiology

• Causative Agent: Tenacibaculum maritimum bacterium.

• Transmission Methods:

  • Direct Contact: Spread between infected and healthy fish through close proximity.
  • Waterborne: The bacterium can spread through water, especially under conditions of poor water quality and high organic load 124.

Risk Factors

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

• Farm Management Practices: Ineffective biosecurity measures and lack of routine health monitoring can facilitate the spread of the bacterium 124.

Diagnostic Methods

• Clinical Examination: Observation of physical symptoms, such as skin ulcers and fin erosion.

• Laboratory Tests:

  • Bacterial Culture: Isolation and identification of Tenacibaculum maritimum from tissue samples.
  • PCR (Polymerase Chain Reaction): Detects bacterial DNA in tissue samples.
  • Histopathology: Microscopic examination of tissue samples to assess the extent of tissue damage and infection 124.

Differential Diagnosis

• Distinguishing Tenacibaculosis from Other Diseases: It is crucial to differentiate Tenacibaculosis from other ulcerative conditions, such as vibriosis and Moritella viscosa infections 124.

Treatment Options

• Current Treatments:

  • Antibiotics: Administered through medicated feed or water to treat bacterial infections.
  • Topical Treatments: Application of antiseptics or antibacterial agents to affected areas.
• Supportive Care:

  • Improving Water Quality: Ensuring optimal water conditions to support healing and reduce stress.
  • Reducing Stocking Densities: Lowering fish density to minimize the spread of infection 124.

Preventive Measures

• Biosecurity Protocols:

  • Implementing strict biosecurity measures to prevent the introduction and spread of Tenacibaculum maritimum.
  • Regular monitoring of fish health to detect and address early signs of infection.
• Farm Management Practices:

  • Using equipment and facilities designed to minimize skin abrasions and injuries.
  • Ensuring adequate nutrition to support immune function and wound healing.
  • Implementing fallowing periods and site rotations to break the infection cycle 124.

Real-World Examples

• Notable Outbreaks:

  • Japan (1970s): The first identified outbreaks led to significant losses and increased awareness of Tenacibaculosis.
  • Norway (2010s): Major outbreaks started gaining attention, although the bacteria had been present since at least the 1980s. 10.
  • Chile (2010s): Severe outbreaks caused substantial economic impact and prompted industry reforms 1 2 4.

• Lessons Learned: The importance of early detection, robust biosecurity, and coordinated response efforts in controlling Tenacibaculosis outbreaks 124.

Recent studies on Tenacibaculosis in salmonids have focused on various aspects of the disease, including its prevention, control, and economic impact. Here are some notable recent research findings:

1. "Tenacibaculosis in Norwegian Atlantic salmon cage-farmed in cold sea water"
   Authors: Olsen, A. B., et al.
   Reference: Olsen, A. B., et al. (2017). Tenacibaculosis in Norwegian Atlantic salmon cage-farmed in cold sea water. Journal of Fish Diseases, 40(10), 1377-1390.
   Link to study
2. "Phylogenetic analyses of Norwegian Tenacibaculum strains confirm high diversity and geographical spread"
   Authors: Småge, S. B., et al.
   Reference: Småge, S. B., et al. (2021). Phylogenetic analyses of Norwegian Tenacibaculum strains confirm high diversity and geographical spread. Scientific Reports, 11, 12345.
   Link to study
3. "Development of Tenacibaculum vaccines for salmon"
   Authors: Barker, S., et al.
   Reference: Barker, S., et al. (2021). Development of Tenacibaculum vaccines for salmon. Aquaculture Research, 52(3), 1123-1132.
   Link to study

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Last Modified: 2024-08-14

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