The Norwegian Veterinary Institute received the first case of sick rainbow trout in hatcheries with an unknown illness in late August 2013. Samples from the second case were received in October and a third case was discovered in early November. Samples from the final hatchery with such disease were received in January 2014.
The illness was reported in fish between 30-100g and sick fish have been in freshwater, or there has been a little sea water (
The National Veterinary Institute has started a minor infection experiment to examine whether the disease is contagious for rainbow trout and salmon.
Sick fish had signs of circulatory failure. Fish may have had a pale body because of anemia and fluid in the abdominal cavity. The histopathological findings show varying degrees of inflammation in the heart, liver and red muscle.
Disease studies using PCR did not detect: Viral hemorrhagic septikemivirus (VHSV), infectious salmon anemia virus (ISAV), pancreas disease virus (SAV) or piscine orthoreovirus (PRV)
However, infectious pancreatic necrosis virus (IPNV) was found in small quantities at a facility.