HSMI
Viral
🟡 Moderate
Heart and Skeletal Muscle Inflammation
🦠 Piscine orthoreovirus (PRV-1) · Reoviridae
📋 Overview
HSMI was first described in Norway in 1999 and is now the second most commonly diagnosed heart disease in Norwegian salmon farming. PRV-1 is extremely prevalent in wild salmon, suggesting it is a natural pathogen that causes disease under intensive aquaculture conditions.
📊 Key Facts
Causative Agent
Piscine orthoreovirus (PRV-1)
Genome Type
dsRNA, 10 segments
Geographic Range
Norway (primary), also UK, Canada, Chile
Transmission Routes
Horizontal, water-borne
Primary Host
Atlantic Salmon (sea-water phase)
Treatment
⚠ Supportive only
Vaccine
✗ None / Experimental
🩺 Clinical Signs
Lethargy, anorexia, swimming at surface, pale heart with petechial haemorrhages, red/white muscle necrosis.
🔬 Symptoms
🔬
Heart inflammation and haemorrhage
Circulatory Subacute
🔬
Red muscle necrosis
Musculoskeletal Subacute
🔬
Swimming near surface
Neurological Acute
🧪 Diagnosis
Histopathology (heart lesions), RT-PCR for PRV.
💊 Treatment
ℹ️ Treatment options are supportive. Consult a qualified fish health professional.
Supportive care, reduce biomass.
🛡️ Prevention
ℹ️ Prevention is the most effective strategy for managing this disease in aquaculture and aquarium settings.
No vaccine. Reduce stocking density, avoid stress.