The 2 main deadly virus AFB and EFB get a lot of attention but there are others Sac Brood, Chalk Brood, Child Brood and others that have not been identified yet. even sprays or contaminated syrups or nectar that poisons to bees will cause brood death even mites. depending when the brood dies will effect what it looks like in the comb. In most cases the bees can clean the dead brood If with a little help from antibiotics. Except for AFB that requires removal of the infected comb. If caught early enough and at a favorable time of the year the bees can be saved. At times I feel it is the genetic offspring of the queen that are poor at cleaning that make one hive more acceptable to the visual effects of the dead brood in the hive.
In BC there is a company that will irradiate AFB Infected supers with the frames and wax and this process kills the AFB spores in the hives and wax.
For all that are thinking bad word.
At times I feel it is the genetic offspring of the queen that are poor at cleaning that make one hive more acceptable to the visual effects of the dead brood in the hive.
All hives in the yard may be effected by a spray, virus, or whatever but the genetics of some hives allows the bees to deal with the situation. Identify that the brood is dead and uncap and remove it before it starts to break down, before the spores can multiply and get to a point where in the process of the bees trying to clean, they are spreading it more. The clean hive may have been effected just as much as the sick looking hive but because they were so much better at dealing with it, we are not even aware that there was a problem with the hive. Because the bees did take care of it there is no problem with the hive.
I have a hive that has bad dead brood. Don't know if it is queen or virus so the queen and returning foragers went in to a clean super of drawn comb on the original location. The brood supers are stacked so the bees can emerge they can raise a queen that I will kill and requeen with a queen in a nuc if I feel that the bees have cleaned the effected brood out. Have to inspect in a week to see what has happened and what further action is required. some times it is a wait and see game.