ISA
Viral
🔴 Fatal
🔔 OIE Notifiable
💉 Vaccine Available
Infectious Salmon Anaemia
🦠 Infectious salmon anaemia virus (ISAV) · Orthomyxoviridae
📋 Overview
ISA is one of the most economically devastating diseases in Atlantic salmon aquaculture. The virus attacks red blood cells causing severe anaemia, multi-organ failure and death. First recognised in Norway in 1984, it has since spread to all major Atlantic salmon farming regions.
📊 Key Facts
Causative Agent
Infectious salmon anaemia virus (ISAV)
Agent Family
Orthomyxoviridae
Genome Type
ssRNA, 8 segments
Geographic Range
Norway, Scotland, Faroe Islands, Canada, USA (Atlantic coast), Chile
Transmission Routes
Water-borne, horizontal fish-to-fish, contaminated equipment
Primary Host
Atlantic Salmon (Salmo salar)
First Described
1984 · Thorud & Djupvik
Economic Impact
Hundreds of millions USD per outbreak
🩺 Clinical Signs
Severe anaemia, pale gills, exophthalmia, haemorrhagic ascites, darkened liver, congested spleen, skin haemorrhages.
🔬 Symptoms
🔬
Severe anaemia
Circulatory Acute
🔬
Exophthalmia (bulging eyes)
Ophthalmic Acute
🔬
Haemorrhagic ascites
Abdominal Acute
🔬
Liver discolouration
Hepatic Subacute
🔬
Congested spleen
Splenic Subacute
🔬
Skin haemorrhages
Integumentary Chronic
🔬
Pale gills
Respiratory Acute
🧪 Diagnosis
RT-PCR, IFAT, virus isolation in cell culture, histopathology.
💊 Treatment
⚠️ No universally approved treatment is currently available. The information below covers supportive care and experimental approaches.
No effective antiviral. Stamping-out (culling) of infected farms is standard response.
🛡️ Prevention
ℹ️ Prevention is the most effective strategy for managing this disease in aquaculture and aquarium settings.
Vaccination (available in some countries), strict biosecurity, fallowing, movement controls.
🏛️ Regulatory Status
🔔 This disease is OIE (World Organisation for Animal Health) notifiable. Suspected cases must be reported to the relevant authorities.
OIE-listed. Notifiable in all major salmon-farming nations.
📅 Historical Outbreaks
1984 Norway; 1996 Scotland; 1999 Canada (Bay of Fundy); 2007–2010 Chile (devastating); 2012 Maine USA.
🐟 Affected Species
2 known susceptible species