Ameriacan Foulbrood (AFB) is not contagious according to Les Crowder

I am reading Les Crowder's new Top Bar Beeking book (which I love) and found something extremelly interesting about the American Foulbrood which I must quote here for educational purpouse that is;

Quote:
He said, "Son, I looked up those bacteria and those bacteria are not pathogenic bacteria; they are putrefactive bacteria. I dont believe they cause the disease; they just decay the dead larvae."
I asked him what he thought caused the disease and he responded with, "the old black combs in the hive, particularly in the brood nest, arelike us trying to stay healthy in a house full of sewage. Those old combs get tick and heavy full of molds and bacteria."

I jumped over a part to this;

Quote:
"The books all say that if you find a hive sick with foulbrood, you should sterilise your hands and hive tool before you open the next hive so you dont spread the disease. I want you to try to spread the disease! Take combs full of sick larvae out of the sick hive, brush most of the bees off, and put the whole stinking comb in a healthy hive. Whatch what happens to the healthy hive. Keep trying if you want. I bet you won't be able to spread the disease, providing you dont fill up the hive with old black combs.."

A week later I did find American Foulbrood in one of my hives. I decided to try Dr. Lyle's experiment. I shook most of the bees off and gave the comb full of dead, decaying larvae to a small, queen mating nucleus hive .... it had a total of four combs and now one of them was filled with foulbrood-infected larvae.
.... .... ....
.... One week later I looked inside there were no dead larvae or any other indication of foulbrood on the healthy combs, and the foulbrood comb had very few sick larvae left. I thought that perhaps there might be an incubation period and that I hadnt waited long enough. When I checked again in another week, the hive seemed disease-free. I gave it another infected comb and watched it all summer. It never got sick."