In these fish species, however, the parasite is benign. For his doctorate, Jørgensen completed genetic studies showing that the disease-causing parasite in farmed salmon is genetically quite different from the species one finds in wild salmonids, although they appear to be identical, even under high magnification in an electron microscope. Based on this observation, the parasite that causes disease in farmed salmon has now been described as a new species – Spironucleus salmonicida.

“Our work has shown that genetic methods need to be utilised for correct identification of single-celled parasites of the genus Spironucleus. Parasites that appear to be identical morphologically may in fact be significantly different genetically. An exact identification of organisms that produce disease is extremely important in the fight to find the cause of disease outbreaks and provides an important contribution to finding appropriate diagnostic methods”, says Anders Jørgensen.