When the spore count gets high enough that larvae are rotting, I get rid of everything inside: frames, comb, honey. Keep boxes top & bot. Treat everybody else. I must say in all honesty I have been my own source of possible infection more than once. 1 out of 112 is low % but who wouldn't treat the rest of the yard? This autumn this year is going to be brutal in Calif, if you bees aren't robbing each other, they probably dead. But AFB is really not a big problem over all.
Tom I hear ya on the neighborhood problem. Not something I have to deal with in the areas I have stationary colonies
I don't move out of state anymore but several Mn commercials that do run MN Hygenic and swear that cleaned up their AFB problems and they don't use any preventative treatments either.
I have yet to find someone with a serious Russian apiary also say they use a preventative and have any AFB.