Basically, I think it has to do with how you import the genetic material, and I believe ISA is endemic to the Atlantic Ocean. So it's there in the wild reservoirs. We don't know what. So the disease is present.
What I believe happened in Chile is that it was brought there with the introduction of smolts, or as fry or infected eggs.
What B.C. has been doing for a number of years is that for the most part they had their own brood stock. They imported eggs a long time ago, basically in the late eighties, before ISA even really appeared, and they have had their own genetics. Any importation of eggs, probably since the mid nineties, has been under strict quarantine and only from facilities deemed to be disease-free, which to date have just been in Iceland. They are the only source from whom eggs are allowed to be imported into British Columbia.