Miroslav Djuric, DVM
Infectious salmon anaemia virus (ISAV) is a pathogen of marine-farmed Atlantic salmon (Salmo salar). However, ISAV can be transmitted experimentally to fish in fresh water. Outbreaks are restricted to Atlantic salmon but other salmonids may harbour the virus and act as reservoirs. ISAV remains an emerging fish pathogen because of the asymptomatic infections in marine wild fish. Natural outbreaks are usually chronic, lasting for several months and mortality varies between 15-100%.
Diagnosis is based on characteristic gross pathology and light microscopy, anaemia and absence of pathogenic bacteria. Supporting diagnosis of the virus is achieved by culture on the salmon head kidney cell line (SHK-1), a polymerase chain reaction (PCR) test or enzyme-linked immunosorbent assay (ELISA).2
ISAV was first diagnosed in southwest Norway in 1984 and has since been diagnosed in Canada, Scotland, the USA, the Faeroe Islands and Chile. The first outbreak of ISAV in marine-farmed Atlantic salmon in the Southern hemisphere occurred in Chile in 2007.