Infectious Pancreatic Necrosis (IPN)

Infectious Pancreatic Necrosis (IPN) is a highly contagious viral disease affecting various fish species in aquaculture, including Atlantic salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss), and other salmonids. It is caused by the Infectious Pancreatic Necrosis Virus (IPNV), a member of the Birnaviridae family, leading to high mortality rates, especially in young fish, and significant economic losses 12. IPN primarily affects juvenile salmonids, particularly in the fry and post-smolt stages, but can also infect adult fish asymptomatically 1.

• Physical Signs:
  • Abdominal Swelling: Distended abdomen due to fluid accumulation 14.
  • Pale Gills: Typically pale gills in affected fish 4.
  • Hemorrhages: Bleeding in internal organs, including ventral areas and fins 4.
  • Darkening of the Skin: Affected fish may exhibit darkened coloration 14.
• Behavioral Changes:
  • Lethargy: Fish lying still on the bottom of tanks or ponds 4.
  • Loss of Appetite: Anorexia and significant weight loss 2.
  • Abnormal Swimming Patterns: Fish may swim in a corkscrew or spiral motion 14.

Progression of Symptoms

• Early Stages: Sudden and progressive increase in mortality at first feeding of fry, particularly in faster-growing individuals 4.

• Advanced Stages: Pronounced physical symptoms such as abdominal swelling, hemorrhages, and darkened skin, leading to high mortality rates of 10% to 90% 14.

• Impact on Fish Health: IPN severely compromises immune function and overall vitality, making fish susceptible to secondary infections 3.

Etiology

• Causative Agent: Infectious Pancreatic Necrosis Virus (IPNV), an Aquabirnavirus 12.

• Transmission Methods:

  • Horizontal Transmission: Spread through infected water and equipment 1.
  • Vertical Transmission: From parent to progeny through infected eggs 1.

Risk Factors

• Environmental Factors: Outbreaks can occur at water temperatures between 4°C and 18°C, with stress factors such as high stocking densities and fluctuations in water temperature and salinity increasing susceptibility 4.

• Farm Management Practices: Movement of equipment from infected sites and improper handling of mortalities and wastes can facilitate the spread of the virus 1.

Diagnostic Methods

• Clinical Examination: Observation of physical and behavioral symptoms 12.

• Laboratory Tests:

  • PCR (Polymerase Chain Reaction): Detects IPNV genetic material in fish tissues 3.
  • Virus Isolation: Culturing the virus in tissue culture 1.
  • ELISA and Antibody Neutralization: For identification of the virus 1.

Differential Diagnosis

• Distinguishing IPN from Other Diseases: It is crucial to differentiate IPN from diseases with similar symptoms, such as infectious salmon anaemia (ISA), infection with salmonid alphavirus (SAV), infectious haematopoietic necrosis (IHN), and viral haemorrhagic septicaemia (VHS) 4.

Treatment Options

• Current Treatments: There are no specific antiviral treatments for IPN. Management focuses on preventing the spread and mitigating the impact through biosecurity measures 13.

Preventive Measures

• Biosecurity Protocols:

  • Testing of broodstock and destruction of eggs from infected parents 1.
  • Avoiding movement of equipment from infected sites 1.

• Vaccination Strategies: A provisional marketing authorization has been granted for a vaccine against IPN 1.

• Farm Management Practices:

  • Maintaining high water quality and low stocking density 2.
  • Implementing strict protocols regarding movement, water sources, and stock replacement 2.

Real-World Examples

• Notable Outbreaks:
  • Scotland: High prevalence of IPNV infection in farmed Atlantic salmon in seawater, with increasing incidence in freshwater salmon farms in recent years 1.
  • Norway: Considerable mortalities from IPN in Atlantic salmon post-smolts 1.

Recent studies on Infectious Pancreatic Necrosis (IPN) in salmonids have focused on various aspects of the disease, including its prevention, control, and molecular characteristics. Here are some notable recent research findings:

1. "The Infectious Pancreatic Necrosis Virus (IPNV) and its Virulence Determinants"
   Authors: Jurado, C., et al.
   Reference: Jurado, C., et al. (2020). The Infectious Pancreatic Necrosis Virus (IPNV) and its Virulence Determinants. Viruses, 12(2), 152.
   Link to study
2. "Susceptibility of rainbow trout to three different genogroups of infectious pancreatic necrosis virus"
   Authors: Mutoloki, S., et al.
   Reference: Mutoloki, S., et al. (2020). Susceptibility of rainbow trout to three different genogroups of infectious pancreatic necrosis virus. Diseases of Aquatic Organisms, 141, 103-116.
   Link to study

These studies represent advancements in understanding the molecular characteristics, prevention, and control of IPN in various regions with significant salmon farming industries.

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Last Modified: 2024-07-26

Tags: #InfectiousPancreaticNecrosis, #IPN, #IPNV, #InfectiousPancreaticNecrosisVirus #Birnaviridae, #Salmonoids, #Salmon, #AtlanticSalmon, #Trout, #RainbowTrout, #ViralDisease, #Virus