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AFB is caused by a spore forming bacterium called Paenibacillus larvae.
These spores are the infective stage of the disease and infection begins
when food contaminated with spores are fed to larvae by the nurse bees.
Once in the gut of the larva the spores germinate, bacteria move into the
larval tissues, where they multiply enormously. Infected larvae normally
die after the cell is sealed and millions of infective spores form in their
remains. Spores are very resistant to extremes of heat and cold, and to
many disinfectants and remain viable for many years.
Symptoms of AFB
The characteristic disease signs of AFB include some or all of
the following:
• Uneven or ‘Pepper-pot’ brood pattern
• Sunken, greasy or perforated, darkened cell cappings
• Roping, sticky larval remains when drawn out with a matchstick
• Dark “scales”, which are difficult to remove from cells
Spread
The most common method of transmission from infected hive to healthy
hive is the beekeeper. The spores can easily be transferred, if frames
of honey or brood are moved between hives, or if other contaminated
equipment is used. However, robbing by adult bees of dead or dying
infected colonies is also an important mode of transmission. If left to
run its course, all colonies infected with AFB will eventually die from
the disease.
Control
The control method for AFB is simple in the UK: all infected colonies are
compulsorily destroyed. The first stage is to destroy the adult bees and
brood combs by burning, then the hives and any appliances are sterilised
by immersing in a greater than 50% bleach solution for 20mins.
American Foul Brood (AFB)
EFB is caused by the bacterium Melissococcus plutonius. Larvae become
infected by consuming contaminated food fed by the nurse bees. The
bacteria multiply within the larval gut, competing with it for its food.
They remain in the gut and do not invade larval tissue; larvae that die
from the disease do so because they have been starved of food. This
noramlly occurs shortly before the cells are capped.
Symptoms of EFB
An infected colony may show some or all of the signs below:
• Erratic or uneven brood pattern
• Twisted larvae with creamy-white guts visible through the body wall
• Melted down, yellowy white larvae
• An unpleasant sour odour
• Loosely-attached brown scales
Unlike AFB, the remains of larvae that die from EFB do not rope when
drawn out with a matchstick.
Spread
As with AFB the bee keeper is the primary method of transmission, if brood
combs other items are transferred from an infected hive to a healthy hive.
However, robbing of weakened infected colonies and swarms are also
methods by which the disease can be transmitted.
Control
There are three options available to the bee keeper in the UK who has
colonies infected with EFB;
1. The colonies may be treated with the shook swarm husbandry
method.
2. The colonies may be treated with the antibiotic oxytetracycline (as the
formulation Terramycin®).
3. The colonies may be destroyed, as for AFB. This will be carried
out if the colony is too small for other treatment methods, is too heavily
infected to respond to treatment, or at the bee keepers request.
However, the range of options available will also depend upon the time of
year that the disease is diagnosed and other factors such as the strength
of the colony or the level of infection. Should EFB be diagnosed in your
bees, these options will be fully explained to you by your local Appointed
Bee Inspector (ABI) to allow the best course of action to be taken.
European Foul Brood (EFB)
Cleaning and sterilising your Beehaus
The Beehaus can be cleaned with a solution of washing soda, made up as
directed by the manufacturer. Using a washing up brush or a sponge clean
all the surfaces to remove dirt and propolis. Do not use a scourer pad as
this will damage the surface of the plastic.
Any debris on the mesh floor should be removed either by brushing out or
using an improvised scoop such as the one pictured made out of a piece of
cardboard. Finally rinse with fresh water and dry.
Sterilising your Beehaus
If you had a disease such as American Foul brood or European Foul brood
in your colony, you will need to sterilise your hive. It is also good practice
to sterilise your beehive if you are selling or purchasing a secondhand
hive.
Unlike a wooden hive, the Beehaus can be sterilised using a strong
solution of household bleach (such as Milton). The bleach cannot sterilise
wax and you therefore need to clean the Beehaus with washing soda to
remove all the wax and propolis before sterilising.
Method
Step 1
- The sterilising solution should be made up as directed by the
manufacturer.
Step 2
- You should wear protective clothing and protective eye wear in
case of splashes.
Step 3
- The Beehaus must then be completely dismantled and all the parts
immersed in the solution to sterilise it. Leave the parts immersed as per
the manufacturers instructions.
Step 4
- Remove the parts and rinse them thoroughly with clean water.
Allow to dry before re-assembling.
Sterilising wooden frames and wax
You can sterilise wax by using gamma rays from a radioisotope of cobalt.
As you probably won’t have a gamma radiation machine to hand, it is
recommended that your dispose of the wax and old frames by burning
them in a fire.
AFB infection, an example of the ropiness test .
Picture credit Crown copyright.
