Glossary
The most serious and contagious bacterial disease of honey bees, caused by the spore-forming bacterium Paenibacillus larvae. AFB kills larvae, produces a characteristic foul smell, and is so persistent that infected equipment must be destroyed by burning in most jurisdictions.
American Foulbrood (AFB) is the most destructive disease in beekeeping. Once established, it is virtually incurable. The causative bacterium, Paenibacillus larvae, produces endospores that can survive for over 70 years in contaminated equipment, soil, and honey. These spores resist boiling, freezing, drying, and most disinfectants. A single contaminated frame introduced to a healthy colony can spell its death sentence.
AFB kills larvae after they have been capped, producing a characteristic set of symptoms. Cappings over infected cells become sunken, darkened, greasy-looking, and may have small holes punctured by worker bees who detect something wrong inside. Opening a suspected cell reveals a brown, gooey mass instead of a healthy white pupa. The definitive field test is the "ropiness test": insert a toothpick or small stick into a discolored cell and slowly withdraw it. If the decomposed larval remains stretch into a ropy string 1 to 2 inches long before breaking, AFB is almost certainly present. The smell is distinctive: a rotten, fishy, putrid odor that experienced beekeepers recognize immediately.
In most U.S. states, AFB-infected colonies must be reported to the state apiary inspector, and the standard protocol is destruction: the bees are killed (usually with soapy water), and all frames, comb, and wooden equipment are burned. The spores cannot be reliably eliminated by any other method. The cost of losing a colony and its equipment, often several hundred dollars, underscores the importance of prevention.
Never feed bees honey from unknown sources (honey can carry AFB spores). Never buy used equipment from unknown beekeepers. Maintain strong, healthy colonies with hygienic queens. Inspect regularly for symptoms. Some beekeepers use prophylactic antibiotics (oxytetracycline), though this practice is controversial because it masks symptoms without eliminating the underlying spore contamination.
Not reliably. The spore-forming nature of the bacterium means it persists in equipment indefinitely. Antibiotics can suppress symptoms temporarily but do not eliminate spores. The standard protocol in most states is burning the infected colony and equipment. Prevention is the only reliable strategy.
No. AFB spores are harmless to humans and animals. The disease affects only honey bee larvae. However, honey from AFB-infected colonies must never be fed to other bees, as it will spread the disease.
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