Glossary
An overview of the major diseases affecting managed honey bee colonies: American foulbrood (AFB), European foulbrood (EFB), nosema, chalkbrood, and viral diseases (deformed wing virus, black queen cell virus). Understanding disease identification, prevention, and treatment is essential knowledge for responsible beekeepers.
The most serious brood disease. Caused by the spore-forming bacterium Paenibacillus larvae. Symptoms: sunken, perforated, greasy-looking cappings; a "ropy" test where a toothpick twisted in an infected cell draws out a 1-inch string of infected material; a foul, rotten smell. AFB spores can survive for 70+ years in contaminated equipment. Treatment: In most states, AFB-confirmed colonies must be destroyed by burning (hive bodies, frames, bees, and all). There is no cure for established AFB infections. Prevention: prophylactic oxytetracycline use was once common but is now restricted due to antibiotic resistance concerns.
A brood disease caused by Melissococcus plutonius. Less severe than AFB: larvae die before capping (twisted, discolored, yellowish larvae visible in open cells), no ropy test positive, and the disease often resolves when colony strength increases. Treatment: requeening with a hygienic queen line; oxytetracycline in severe cases.
An intestinal disease caused by microsporidian fungi (Nosema apis and Nosema ceranae). Causes dysentery (brown streaking on the hive exterior), reduced colony productivity, and shortened adult bee lifespan. Nosema ceranae is increasingly prevalent and does not always produce the classic dysentery symptoms. Treatment: Fumagillin (where available/legal); good nutrition and strong colony management reduce susceptibility.
Deformed Wing Virus (DWV): Transmitted by varroa mites. Infected bees emerge with crumpled, useless wings and shortened lifespans. The visible symptoms represent a colony in crisis from uncontrolled varroa. Treatment: control varroa mites. There is no direct antiviral treatment. Black Queen Cell Virus, Israeli Acute Paralysis Virus, and others are also varroa-vectored, reinforcing that mite management is the foundation of disease prevention.
Key warning signs: spotty brood pattern (many empty cells among capped brood), discolored larvae (yellow, brown, or black instead of healthy pearly white), sunken or perforated cappings, bees with deformed wings crawling on the ground, foul odors from the hive, excessive dead bees at the entrance, and brown streaking on the hive exterior (nosema/dysentery). If you suspect disease, contact your state apiary inspector for a free diagnostic visit.
No. The bacterial, fungal, and viral diseases of honey bees do not infect humans. Honey from a diseased colony is safe for human consumption (honey's antimicrobial properties prevent pathogen survival). However, honey from AFB-infected colonies should not be fed back to bees, as it can spread the disease to healthy colonies.
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