There are immunity against against European foulbrood too. You must only change ypur queens to tesistant genepool and goodbuy to the EFB.
I am a bit sorry a lot of people get all worked up about how you say things then forget to LISTEN to some of the wisdom that comes from you.
In that line you have the nub of the issue.
In the areas where our friends in Italy operate they have practically eliminated EFB through proper scientific breeding, requeening vulnerable stock, and keeping the levels of selection and breeding high.
Unfortunately much of this is in bees that are not especially suited to our climate in Scotland....or indeed Irel;and or along the seaboard of NW Europe with a maitime climate, so we have a long term job on our hands to get this property into our own stock, so Jolanta is off to a distant land soon to be trained by a world expert. Although you are afar north in Europe, Finland still has a relatively continental climte and so this Italian based Buckfast stock is pretty well suited to YOUR climate. Some of the queens we have been testing are of Finnish origin via northern Italy.
However, even now, we have got well on top of chalk to the point we rarely see the heavy chalkbrood so common in local black bees, and EFB frequency is in decline (although that is subject to attack on multiple fronts). The severity of EFB is also in decline, finding 'stinkers' as was the case 12 yrs ago is now pretty well a non occurrence, most cases are very subtle. As hygiene increases and chalk susceptibility declines we can now use ';spotty brood' as a VERY strong indicator that EFB may be present and do a test.
We xare getting there....but suspect the proper job will take another 10 to 15 years...meantime we suffer constant genetic influx from local stock, which for reasons of there own, is revered by people whose mind is more about conservation of local survivors than high performers.
I have said this many times before.......and of you are in a clean area it is not a worry and your experience does not relate to this...but we are a pretty significant sample size and have been through hell on the EFB front since 2009. You can almost start to predict the groups of colonies most at risk. Our statistics over the years have shown that the more Amm the bees are the greater their susceptibility to EFB and chalk. In fact for EFB we are pretty sure it is between 10 and 40 times more likely in Amm, and tending to Amm, colonies.
Our thoughts on that are more tempered in the last couple fo years by the fact semi hygienic bees are good cleaners and you might not see it. Subclinical levels paint a far less clear picture. What IS clear is that we face a permanent situation of needing to refresh the resi8stant/tolerant traits as incoming dro9nes into field matings especially will constantly dilute the effects of the work at the breeding unit. I suspect we may still be having these arguments and problems in 50 years.
Meanwhile we have a bee establishment that seems to believe all the reports on this from other countries are false and an NBU whose official line is you cannot resolve EFB through breeding. We are paddling upstream against the current.