Not great newt. Slowly fishery owners are becoming aware of the dangers and are insisting on health certification. The greedy foolish ones are not and ultimately they suffer through loss of stock. I have witnessed lakes full of dead and dying fish which have later been traced to illegal imports. The general import is 20lb+ carp. Carp exceeding 35lb+ can sell for over 5000, but only if they are English fish. An illegal import of similar size would cost a mere percentage of that, however, the risk of stock wipe out is hugely increased. Although catfish, grass carp and the sturgeon are being imported this is not so common. These fish are difficult to pass as indigenous species - the look nothing like roach!! However, they still come into the country, fishery owners buy them and anglers rush to fish for them. If the demand falls away then the obvious will occur. Sadly i don't think it will.
As for svc spreading, I consider myself in touch with the current consultancy scene and i do not know of any cases for quite a while. The original importer of svc diseased carp served a 6-year prison sentence. Deserved you may think, but fish are still dying of it twenty years on and he is back importing illegal fish - that's reality and the world of dubious fishery consultants. There are many of them around. All i can offer is an impartial view to all of those members of md.com If your club wants to buy fish e-mail me and i will suggest the most reputable dealer in your area. Can't say fairer than that.
Mat