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Diseases - Foul Brood - FAQs

FAQs - Disease Background

What is EFB?

EFB (European foul brood) is one of four notifiable diseases/pests of honeybees in Scotland.

EFB is caused by the bacterium Melissococcus plutonius which multiplies in the mid-gut of an infected bee larva and competes with it for food, causing the larva to starve to death. Once the larva is dead other species of bacteria may multiply in the remains of the dead larvae as "secondary invaders", such as Paenibacillus alvei, Enterococcus faecalis, Brevibacillus laterosporus, and Lactobacillus eurydice.

EFB cannot be reliably identified visually, as the disease signs can easily be confused with various other brood abnormalities (e.g. Parasitic Mite Syndrome associated with heavy infestations of Varroa). This outbreak has been particularly difficult to diagnose but it has been confirmed that it is of the typical EFB strain (and not a 'new variant' as initially thought).

What are the symptoms?

The symptoms of EFB include:

  • erratic or uneven brood pattern
  • discoloured cappings
  • twisted larvae with creamy-white guts visible through the body wall
  • melted down, yellow larvae, almost like wax
  • unpleasant sour odour (sometimes like rotting fish)
  • loosely-attached rubbery brown scales
  • lack of ropiness in the matchstick test
  • when larva dies it will lie unnaturally - spirally twisted around cell wall/cell mouth or stretched out lengthways from mouth to base

This outbreak has been difficult to diagnose in several ways, for example:

  • sealed broods are mainly affected - shown by occasional sunken perforated cappings
  • the Lateral Flow Device ( LFD) strip test has shown a negative or very weak positive result
  • it occurs in colonies suffering a relatively high mite load which also causes an erratic brood pattern.
  • visible symptoms in unsealed brood have often been masked by bees cleaning cells, leaving signs only under cell cappings.
How does it spread?

EFB can be spread by the beekeeper's protection (e.g. gloves) and tools (e.g. hive tool, smoker, drone fork) during transfer of combs and brood from an infected hive to a healthy one.

The disease can also be transmitted by robbing (the act of bees stealing honey/nectar from the other colonies; also applied to bees cleaning out wet supers or cappings left uncovered by beekeepers) and swarms (a collection of bees, containing at least one queen that split apart from the mother colony to establish a new one; a natural method of propagation of honey bees).

How was the EFB outbreak in Scotland discovered?

Fera contacted the Scottish Government regarding an incident of AFB in Lancashire where it was thought that the bees had been supplied by a beekeeper from Scotland. Because of this notification, the Scottish Government approached the beekeeper in question who has fully cooperated with the Government Inspectorate.

Does EFB infect other species of bee or pollinator?

No, although it could infect them but the nature of overwintering would remove the infection.

When did the disease last occur in Scotland?

The last reported outbreak of EFB in Scotland happened in the Fife area during June 2007. After a follow-up visit to the apiary in August 2007 it was confirmed that there was no further evidence of EFB.

What areas are covered by the surveillance zones?

If EFB is suspected then all colonies in an apiary should be inspected and combs examined by an authorised person. If EFB is confirmed then contact colonies should also be inspected. Contact colonies are defined as "all colonies belonging to the owner of an apiary wherever they are sited, i.e. including colonies transferred from the apiary to another site, during the current season, and all colonies in the vicinity, normally defined as within 5km (3miles), belonging to another owner".

What should I do if I suspect one of my hives has EFB?

If there is a suspected outbreak of EFB in a hive then the beekeeper has a legal obligation to notify their local bee inspector. Scottish Government inspection staff will make contact with the beekeeper upon notification and arrangements will be made to visit the apiary.

  • There are several steps that a beekeeper should take if EFB is suspected in a hive:
  • notify the Bee Inspector at the local Scottish Government Area Office
  • close the hive
  • reduce the hive entrance to prevent robbing
  • disinfect all beekeeping equipment and gloves before examining other colonies
  • do not remove any hives, bees or equipment from the site until the disease (if confirmed) has been controlled - this is a self-imposed standstill which is a legal requirement under legislation.
How do I test a hive for EFB?

Inspections should be carried out by Scottish Government Bee Officers trained to recognise the symptoms of disease and to undertake disease control. On-site tests can be carried out using a Lateral Flow Device ( LFD) strip test, however this has sometimes returned negative or very weak positive results and therefore further tests should be completed at SASA.

(Contact details: SASA, Entomology Laboratory, Roddinglaw Road, Edinburgh, Scotland, EH12 9FJ; Email: info@sasa.gsi.gov.uk, Tel: 44 (0)131 244 8890).

I have sent my sample to SASA, how long will it take to receive the results?

SASA would aim to report their findings to the Bee Inspector on the same working day of the test being completed. If samples are referred to the National Bee Unit ( NBU), then diagnoses should be available within 3 working days.

What should I do if one of my hives tests positive for EFB?

If a hive tests positive for EFB then it should be closed immediately and all other hives within 5km should also be tested. The beekeeper with the infected hive should consider the options for treatment and not move any hives until any movement restrictions are lifted.