So my parents won the bee lottery recently... the bad kind (photo above by Photo above by Doug Somerville). American Foulbrood (AFB) is really rare, but of course, if your hives do manage to get it, it's definitely something to be sad about. Contraction of AFB essentially means the entire hive must be effectively destroyed (more on that later).
This website covers very well what American Foulbrood is all about, so I'll let you read their articles about it instead of re-explaining everything here:
The easiest way to identify the early stages are strange, patchy, flat-topped larval cappings. Usually honey and larvae aren't in the same frame (important as honey is usually created with flat capping). Larvae generally have large round-topped caps that look sturdy and secure. AFB will usually have larval caps that are thin, flat, sometimes discolored, and very fragile looking.
My parents thankfully caught it early in its development so ropiness was relatively minimal and not much of the hive had been affected. This being the case, they isolated the hive in new equipment far away from all the other hives (to prevent robbing and ensure spores weren't spreading to other hives) and hoped that they would be able to re-build themselves well enough without more of the spores infecting their new hive.
The hive they isolated was my strongest hive from when I conducted my experiments in Stillwater. They were literally power bees. I'd never seen a hive that could be so strong, build so much, so quickly... insanity. So, it was a shame to hear the best hive I had (and still the largest and strongest hive my parents have now) was struggling with foulbrood.
My mother kept me updated through the process and while the bees were recovering very quickly in their brand new home (with a dose of various medications with hopes of controlling an outbreak (i.e. another reason to isolate them, because my parents can't consume any honey from a medicated hive and wouldn't want the medication to spread to other hives either)), and there was no additional evidence of foul brood so far.
Then, to their dismay... the hive swarmed.
They might have actually recovered if they hadn't swarmed because that queen produced some of the best super-soldier bees I'd ever seen; however, there was no way to be certain whether or not the bees could actually recover and definitely no way to ensure that the swarm (if they left the property) wouldn't spread any spores to some other area. So, unfortunately, my parents had to kill the entire hive to responsibly prevent the risk of the spores spreading to other areas in town.
To quote the website I posted the link to earlier: "The disease is not able to be cured, meaning that destruction of infected colonies and hives or irradiation of infected material is the only way to manage AFB."
Unfortunately, as the site mentioned there is no cure for American Foulbrood and usually the best course available is to burn the entire hive, box, frames, wax, tools, everything that came in contact with the hive has to be effectively destroyed or disinfected. As the spores have a fairly long half-life and are resistant to most low and high temperatures, unfortunately, an accelerant is usually used in the burning of a foul brood hive. Care needs to be taken when burning an AFB hive because a fire lit with lots of wind could carry any airborne spores with it, thus potentially harming another hive in the long-term, but I believe the concern of spreading in this manner is minimal.
So, it's sad to say my parents strongest hive (and my ex-hive) is now gone, for the safety of all the other hives. Such a shame too, that hive, as I've mentioned... full of super-bees. Honestly insane how quickly they could grow and create. My dad had to go into their hives regularly to clean out all the extra wax they were trying to make because somehow they always ran out of room so quickly.
Anyway, the situation ended as I thought it would, with the end of that hive, but so far all the other hives seem healthy. They've been keeping an eye on everything, looking very closely for any potential spreading and so far everything has come up clean. Hopefully it stays that way.