Monitoring and combating ISA in Norway

Published 25.03.2015     Modified 27.03.2015

Infectious Salmon Anaemia (ISA) is a serious infectious disease in Atlantic salmon. The Norwegian Food Safety Authority (NFSA) has therefore a contingency plan, which has been implemented in accordance to EU law.

Facts about ISA

  • Infectious salmon anaemia (ISA) is a viral disease in Atlantic salmon.
  • There are several strains of the ISA-virus: One strain (HPR0) is not unusual and can be found in Atlantic salmon in Norway and other countries, which farm Atlantic salmon in the sea. This strain is not pathogenic, but can in some rare cases change into variants which can be pathogenic to fish.
  • The disease was first described in Norway in 1984 and has since been found in several countries: USA, UK, Canada, Faroe Islands, Chile. ISA remains present in Norway, Canada and Chile.
  • In Norway there were ten outbreaks of ISA diagnosed in 2014, seven in Nordland, two in Troms and one in Møre og Romsdal. The number of outbreaks was the same as in 2013.

This contingency plan is put into force immediately when suspicion of disease occurs. ISA is a wide spread disease and major outbreaks have been recorded in most countries with significant salmon aquaculture industry.  Fish viruses are not harmful to humans and it is safe to consume Norwegian farmed Atlantic salmon.

The Norwegian Food Safety Authority is responsible for a correct diagnosis of ISA and the programme to combating the disease.

How is ISA combated?

In case of ISA suspicion, the fish farm will immediately be held in quarantine by the NFSA. Information about the suspicion will be published on the NFSAs official webpage and NSFA will start epidemiological investigations.

In case of a confirmed diagnosis of ISA, a protection zone and surveillance zone is established and several measures are implemented to control and combat the disease.

An important part of the programme is to immediately slaughter and\or destroy diseased fish from the quarantined  establishments .

All farms within the protection zone have to slaughter out the fish before the restrictions are lifted. In addition, a fallowing period is implemented for minimum of 2 month for the whole zone and a minimum of 3 months in ISA infected sea farms.

The NFSA is responsible for the control and supervision of the actions taken in case of a disease outbreak and will supervise cleaning, disinfection and fallowing of the facility, risk-based surveillance and regular inspections until the restrictions are lifted. This is done in accordance with EU regulations.


The Norwegian legislation has extensive lists of notifiable diseases and the fish in the farms are monitored in several ways. According to the legislation the farmer has to inspect the fish daily and immediately contact a veterinarian, an aqua medicine biologist or the NFSA if a listed disease is suspected. All freshwater farms are obliged to be subject to a minimum of twelve health inspections by a veterinarian or an aqua medicine biologist (animal health professional) annually. In on-growing farms in sea the number of annual health inspections is six.

Certain diseases are subject to a monitoring system to document freedom. Classification of diseases is carried out according to a specific grading system in accordance with the severity of the disease in accordance with the standards of the OIE. The official monitoring programme run by the NFSA and the surveys are performed by accredited veterinary diagnostic laboratories.

Outbreaks of ISA are reported in accordance with EU regulation and OIE guidelines and are published on interactive maps on the official web sites oh the NFSA.

Norwegian farmed Atlantic salmon is safe to consume

Viruses that cause disease in fish are not pathogenic to humans.  The most important reason for this is that fish are cold blooded animals, which have a much lower body temperature than humans. Virus and bacteria that cause disease in fish can therefore not exist in the temperature in human bodies. Thus fish viruses are not harmful for humans, and it is safe to eat Norwegian farmed Atlantic salmon.

Both farmed fish and wild fish are indigenous to an environment where millions of bacteria and viruses exist in ever drop of water. These are a natural part of the environment and important for nature’s balance.

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Contact information

The press officer, tel. +47 469 12 910

Contact information

The press officer, tel. +47 469 12 910