Infectious Salmon Anaemia (ISA) has now been confirmed at a Mowi site in the northernmost part of Western Norway.
Mowi notified the Norwegian Food safety Authority early last month that the company suspected ISA at the farm know as the Bjørlykkestranda site.
The suspicion was based on the results of PCR analysis carried out at an external laboratory after sampling of fish at the site.
The Norwegian Food Safety Authority said it inspected the facility and took its own samples a few days later.
The authority confirmed it has now confirmed the diagnosis on the basis of test results from the Veterinary Institute which show that ISA virus and disease changes have been detected in the same fish, the Norwegian Food Safety Authority states in a statement on Friday.
In order to limit the spread of infection, the site has been subject to restrictions, including a ban on the movement of fish without special permission.
Slaughtering is already underway, and the operation should be completed within the next few days.
The Bjørlykkestranda site is located in a monitoring zone for ISA. An expanded control area will soon be established to prevent, limit and combat ISA.
Concern has been growing at the increasing number of ISA outbreak along the Norwegian coast this year and an investigation onto possible causes is currently underway.
The high number of outbreaks have also proved very costly for salmon companies who are usually forced to slaughter the entire stock at a farm where an outbreak has been confirmed. ISA is not harmful to humans.