Foul brood is a term used to describe a serious bacterial infection that affects bee colonies. The disease can be devastating for beekeepers and their hives, leading to the loss of entire colonies if left unchecked. Synonyms for foul brood include American foulbrood, European foulbrood, and sacbrood virus. American foulbrood is the most serious form of the disease and is caused by a bacterium that destroys larvae in the hive. European foulbrood, on the other hand, affects younger larvae and is less fatal. Sacbrood virus, meanwhile, affects the pupal stage of bees and can result in malformed or weakened adults. Monitoring and treatment of foul brood is essential for the survival of bee colonies.