European Foulbrood (EFB)
European foulbrood (EFB) is a serious, bacterial disease of honeybee brood found throughout the world. It appears to be increasing. EFB is sometimes not regarded as such an important disease as American foulbrood (AFB), but the two are often confused or mis-diagnosed.
Information about another brood disease: American Foulbrood (AFB)
EFB is easiest to spot in early spring and summer, but the pathogen may have been lurking for a long time. EFB infection can involve many organisms, so the symptoms vary and diagnosis is not always straightforward.
Vita has developed a quick and effective Vita EFB Diagnostic Test Kit for beekeepers to test for EFB (and one for AFB) easily and quickly. The test can be carried out beside the hive and the results are available immediately.
Bee larvae infected with EFB appear twisted in their cells, sometimes forming an unnatural C-shape along the sides or in the bottoms of the cells. The tracheal system tends to stand out and appear silvery, and the gut is sometimes visible through the opaque body tissue.
The infected larvae turn yellow and then brown eventually drying to rubbery scales within the cells. Unlike AFB, the cadaver cannot be “roped out” with a matchstick and it is not glue-like as in AFB. These drier EFB scales can be more easily removed by the worker bees and so EFB can be very difficult to spot.
In severe infections the colony has a foul, rotten odour (hence the name ‘foulbrood’) but this is only one possible symptom of the disease.
The brood pattern in EFB-affected colonies can be patchy (similar to AFB infections).
How EFB spreads
The main cause of an EFB infection is Melissococcus plutonius, but several bacterial organisms can be involved.
As with other diseases, EFB infections are often linked to stress brought on by a lack of food, water, space or attack by another disease or pest. However queen genetics, weather and geography may also play a part.
EFB infection tends to be localised and often recurs in the same apiaries year after year. But it can also spread quite easily.
Very young larvae are particularly susceptible and become infected through brood food contaminated with M. plutonius. The bacteria multiply rapidly in the larval mid-gut reaching such enormous numbers that the bacteria compete with the bee for food supply. The larvae then starve – usually about the time of cell capping.
There is no known effective cure for EFB, but good beekeeping practice and vigilance can reduce the risks.
The Vita EFB Diagnostic Test Kit can give an early warning of the disease.
Vita Feed Gold can help keep your bees healthy and reduce stresses on honeybees, thereby making them more resilient to attacks by disease.
M. plutonius may be very widespread and present in many colonies but goes unnoticed until obvious symptoms of EFB are triggered by other stresses on the colony.
Even though M. plutonius is not a spore-forming bacillus, some bacteria may survive on combs to re-infect at a later date.
A “shook swarm” method is recommended by the National Bee Unit of the UK. This involves shaking the adult bees from an infected comb into a new or sterilised hive with fresh foundation. Using this method, the recurrence of EFB is very much reduced.
In other countries, administration of oxytetracycline is permitted as a preventative as well as a curative treatment. But there are serious difficulties associated with this approach including costs to the beekeeper, residues of antibiotics in hive products and the emergence of oxytetracycline-resistant bacteria.