American foulbrood is a type of bacterial disease caused by the spore-forming Paenibacillus larvae, is the most widespread and destructive of the bee brood diseases in the US. Larvae up to 3 days old become infected by ingesting spores that are present in their food. Spores germinate in the gut of the larva and the vegetative form of the bacteria begins to grow, taking its nourishment from the larva. Infected larvae normally die after their cell is sealed. Each dead larva may contain as many as 100 million spores. This disease only affects the bee larvae but is highly infectious and deadly to bee brood. Infected larvae darken and die.