Go back and read again Bob.
1 dead fish straight from the bag.
All dead/sick fish in QT the entire time before any opportunity for introducing any Canary Koi from the existing population.
Separate water, filtration, equipment, etc... and a covered and completely isolated QT from the main pond, in the hands of a trained medical professional with sterilizing station for QT gear.
I'm betting these QT protocols are comparable to the better dealers in the country and far better than most.
3 Separate lab tests, detailed results, from one of the premier KHV researchers in the country.
Need More???