Abstract
Infectious salmon anaemia ( ISA ) is a serious disease of farmed A tlantic salmon caused by the aquatic orthomyxovirus infectious salmon anaemia virus ( ISAV ). ISA was first detected in N orway in 1984 and was characterized by severe anaemia and circulatory disturbances. This review elucidates factors related to the pathogenesis of ISA in A tlantic salmon, the dissemination of the virus in the host and the general distribution of the 4‐ O ‐acetylated sialic acids ISAV receptor. The knowledge contributes to the understanding of this disease, and why, almost 30 years after the first detection, it is still causing problems for the aquaculture industry.