The other virus
The threat of ISA has returned and scientists are urgently looking for an answer
While global attention has naturally been focused on Covid-19 this year, Norway’s salmon farmers have been worrying about another kind of viral disease – and one that in its own way could be almost as damaging, if it is allowed to get out hand. This particular bug is known as infectious salmon anaemia (ISA) and the number of outbreaks has been climbing to levels worrying both the industry and the government.
With at least 23 confirmed cases plus several suspected outbreaks, they are currently running at their highest level for 30 years. It has proved particularly costly for companies like Grieg and others in the salmon farming industry.
The industry and Norwegian veterinary organisations are currently carrying out a major investigation into why there have been so many cases, but it may be a while before the results are known.
When it attacks, infectious salmon anaemia moves quickly using pathways.Tackling outbreaks involves intensive culling of infected pens which can sometimes mean entire farms. It is mainly found in farmed Atlantic salmon, but it can also affect farmed rainbow trout.
The disease has even shown its potential to destroy national salmon farming industries, tragically exemplified by the epidemics in Chile between 2007 and 2009.
Failure to act promptly can lead to the disease spreading to neighbouring sites, resulting in severe impact on both the local economy, where fish farming is sometimes the only employment activity, and on animal welfare.
Reports of ISA in Norwegian waters have been coming in steadily since early Spring, with the Finnmark and Troms regions bearing the brunt. Scientists and veterinary officials are baffled as to why there has been such a sharp rise in recent months. Hardly a week now seems to go by without at least one new outbreak.
Geir Bornø, who is section leader for fish diagnostics at the Norwegian Veterinary Institute, told the national broadcaster NRK recently: “We do not have the necessary knowledge about why the situation is as it is this year.”
Fredd Wilsgård, head of Wilsgård Fish Farming, another company which has been affected, told NRK that the ISA issue should be taken up at the highest level in an effort to find a solution. He also wants the thinking around the disease to change, with everyone taking a fresh look at alterations to regulations, framework conditions and contingency plans.
He added: “This is extremely important because there can only be good solutions if the industry and the administrators are able to work in teams and agree on how we should attack this problem.”
He believes that with the right co-operation, it is possible to reach a situation where there are virtually no outbreaks.
“If ISA is detected at a fish farm, the costs can average around NOK 100 million (£8.3 million).That sort of figure can get you