The ISA virus was detected at Finnstein-11353, Troms, and was verified as a deleted, virulent variant based on sequence analysis of ISAV HPR (segment 6).
From an epidemiological point of view, the Norwegian Food Safety Authority considers the ISA outbreak at Finnstein-11353 likely to be a first occurrence.
Infectious salmon anaemia (ISA) was present at another location in Troms region in March 2014 as well.
The previous outbreak occurred at a distance of about 250 km, and these ISA cases seem to be two separate outbreaks without any epidemiological correlation although both of them belong to the same administrative region.
The Norwegian Veterinary Institute use genotyping to determine whether ISA outbreaks are an occurrence or a reoccurrence.
Genotyping based on the complete ISAV segment 6 and further epidemiological studies are required to determine if this is an isolated outbreak. This work is ongoing at the Norwegian Veterinary Institute.
Of the 1,158,549 salmon susceptible at the farm, the outbreak led to 2,830 cases resulting in 2,530 deaths and 142,817 salmon being destroyed.
