[PKD: the proliferative kidney disease in fish]

Area of Science:

• Ichthyopathology
• Parasitology
• Aquatic Animal Health

Context:

• Proliferative kidney disease (PKD) poses a major threat to salmonid populations in Europe and North America.
• This disease causes substantial economic losses in aquaculture and impacts wild fish stocks.
• Brown trout in Swiss rivers exhibit high prevalence of PKD.

Purpose:

• To provide an overview of current knowledge on fish proliferative kidney disease (PKD).
• To review diagnostic methods for PKD.
• To highlight knowledge gaps critical for future research and management.

Summary:

• PKD is characterized by kidney tissue proliferation and presents with nonspecific symptoms like anemia and apathy.
• The causative agent is Tetracapsula bryosalmonae (Myxozoa), with its life cycle linked to freshwater bryozoans.
• Disease outbreaks typically occur in summer at temperatures above 15°C, leading to high mortality.
• Diagnosis involves light microscopy, lectin immunohistochemistry, and molecular techniques.

Impact:

• Effective management strategies for PKD are hindered by incomplete understanding of the parasite's life cycle and disease pathogenesis.
• Further research is essential to close knowledge gaps and mitigate the impact of PKD on fish populations.
• Improved diagnostic capabilities support timely intervention and disease control efforts.