EHN
Viral
🔴 Fatal
🔔 OIE Notifiable
Epizootic Haematopoietic Necrosis
🦠 Epizootic haematopoietic necrosis virus (EHNV) · Iridoviridae
📋 Overview
EHN is caused by an iridovirus and is OIE-listed due to its potential to devastate salmonid aquaculture if introduced outside Australia. The disease killed thousands of redfin perch in Lake Purrumbete in 1986 and has caused recurrent epidemics in Australian inland waters.
📊 Key Facts
Causative Agent
Epizootic haematopoietic necrosis virus (EHNV)
Geographic Range
Australia (endemic); strict import controls elsewhere
Transmission Routes
Water-borne, fish-to-fish contact, contaminated equipment
Primary Host
Redfin Perch (Perca fluviatilis), Rainbow Trout
Vaccine
✗ None / Experimental
🩺 Clinical Signs
Lethargy, loss of orientation, pale liver with focal necrosis, swollen spleen and kidney, haemorrhages in muscle and viscera.
🔬 Symptoms
🔬
Pale liver with necrotic foci
Hepatic Acute
🔬
Swollen spleen
Lymphatic Acute
🔬
Haemorrhages in muscle
Musculoskeletal Acute
🔬
Lethargy and disorientation
Neurological Acute
🧪 Diagnosis
Cell culture, PCR, EM, histopathology (basophilic intracytoplasmic inclusions).
💊 Treatment
⚠️ No universally approved treatment is currently available. The information below covers supportive care and experimental approaches.
None effective. Stamping-out and movement bans.
🛡️ Prevention
ℹ️ Prevention is the most effective strategy for managing this disease in aquaculture and aquarium settings.
Strict import controls, biosecurity, aquatic movement restriction orders.