Yes indeedy and therein lies the problem.
Such things as SVC, KHV, Aeromonas, etc. are spread 'round the world with the koi trade. At the same time much of the Third World is dependent upon common carp as a source of high quality protein.
When you look at the koi hobby, a bunch of exceptionally wealthy individuals and groups keeping fish for pets and other reasons, but not dependent upon them for food, then look at the billions of folks that depend on carp solely for food...
The trade in koi for a few very wealthy folks puts the food supply of many very poor folks at risk, the world has problems with it.
Mention New Zealand. When I was at the AJS in Kobe, '92, there was a fella there from New Zealand, actually three fellas. One was interested in koi the other two were NZ Federal Wildlife Agents.
IN another post there was a link to a NZ carp fishing page. Just looking at the data from that page, koi have made inroads inot the native and pristine habitats of New Zealand and the folks are trying to stop them.
So its not just food supplies at risk to the koi trade, it is pristine and unspoiled ecosystems also at risk of destruction from the koi trade.
What can we do as responsible koikeepers? First is to be that, responsible. Don't be turning unwanted koi specimens loose into the environment, destroy them or take them somewhere to be destroyed if no suitable home is available. Give the impression that you "care so much for your koi that you cannot do the right thing with unwanted ones" and you give the impression that you can and will do harm, irreparable harm, to the local ecology.
Give the impression that you "care so much for your KHV surviving koi that you cannot do the right thing" and you give the impression that you are willing to starve a large portion of the world just to save your infected pets. Destroy KHV survivors and let everybody know you've done so, as a responsible and ecologically sensitive koikeeper.
Koikeeping is a wonderful hobby, but it is important to keep it in perspective.
Brett