Infectious Salmon Anemia: The Current State of Knowledge Regarding ISAV

Infectious Salmon Anemia (ISA), first reported in Norway in 1984, is caused by Isavirus salaris (ISAV), which has two phenotypes: pathogenic (HPRΔ), causing high mortality in farmed Atlantic salmon and significant economic losses, and nonpathogenic (HPR0), which is widespread but non-lethal. However, HPR0 poses a persistent threat due to its potential to mutate into pathogenic forms, complicating detection, study, and containment. This challenge is exacerbated by its presence in farming sites, hatcheries, and wild fish populations. Effective control relies on strict regulatory policies, while future strategies focus on developing biotechnological vaccines and genetically resistant salmon through selective breeding. This review synthesizes peer-reviewed literature and governmental data to evaluate the global status of ISAV and its impact on the salmon farming industry.