- Mortality 30%
- Infectivity 90%
- Healing difficult 20%
EFB is a bacterial disease of honey bee brood. It is considered less virulent than American foulbrood, and colonies sometimes recover from infection. Its field symptoms are easily confused with those of AFB, but there are important differences. Instead of being a healthy pearly white, larvae with EFB appear off-white, progressing to brown, and are twisted in various positions in the cell. Larvae with EFB usually die before they are capped whereas larvae with AFB die after they are capped.
The sanitation precautions recommended in the section on AFB apply also to EFB. Likewise, bee stocks selected for hygienic behavior can be expected to minimize outbreaks of EFB. The disease sometimes goes away on its own at the onset of a strong nectar flow. The beekeeper may be able to control the disease by simulating a nectar flow (by feeding sugar syrup) and by requeening the colony.
Preventive biennial treatments with Terramycin antibiotic, as recommended in the section on AFB, will also prevent EFB. As with AFB, it is important to consider antibiotic treatments as a preventive measure, not a cure. Terramycin treatments in EFB-infected colonies may actually be counterproductive because the medication permits those infected larvae to survive which would otherwise perish. These survivors then persist in the colony as a source of contamination. If the infected larvae are instead permitted to die, the house bees eject them from the hive and with them goes the source of infection. The bacterium does not form long-lived spores that persist on hive surfaces.