Infectious salmon anemia – a great challenge to the salmon farming industry

Abstract

Infectious salmon anemia is caused by an aquatic orthomyxovirus called the infectious salmon anemia virus. It causes a devastating disease in salmon characterized by lethargy, anorexia, anemia and death. It is of great economic and commercial importance in the salmon farming industry all over the world. Infectious salmon anemia virus infects several species of fish, but Atlantic salmon seem so far to be the only species displaying the devastating clinical symptoms of the disease. One of the main difficulties in the diagnostics of the disease is that the course of the disease may vary greatly from outbreak to outbreak. Some outbreaks are rapidly onset with mortalities reaching over 90%, while others develop slowly over weeks or even months, with increasing mortality in the pens. Concomitant diseases may also mask the symptoms of ISA, making it even more difficult to catch early on.