Yeah I'm stateside and also heard of the disease, I remember it being called vh something, believe it occurs in smallmouth, ESox, walleye, drum and several others, I'd trace my buyers, but if it doesn't work I'll try something else
so European Esox have a natural immunity to it, while N.A. Esox do not? Sounds like the same reason you don't keep a Boa constrictor and a Ball python in the same enclosure....