I dont know much about how EFB and AFB come about. I only knew both are staburn deseases that many beekeeper afraid of.
I found recently there were some combs that shown big number of cells have death pupas, where worker bees were busy removing or eating them away. The death pupas looked clean, and found no mite. Hives found strong, honey and pollen supply were enough. So, I suspected they were attacked by EFB.
Within radius of 100km, there is no Italian beekeeper. So I dont think the desease (if there is) was brought by swarm hives.
I only noticed in the apiary where I got my nuc hives, over there have hives most likely attacked by AFB. The death larva appeared brownish, and body was curled. So far, my hives have no such problem.