American
Foul Brood
Causal agent |
Paenibacillus larvae Slender rod with
slightly rounded ends with a tendency to grow in chains. Produces spores.
Does not grow on nutrient agar requires Difco
brain-heart infusion. |
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Other names |
AFB |
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Age group |
Larvae after capping
worker 12 days of age Some strains may
attack uncapped larvae |
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Egg |
Larvae |
Pupae |
Adult - worker |
Drone |
Queen |
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No |
Yes |
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Clinical signs |
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Season |
Any time |
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Odour |
There is a
characteristic odour (decayed glue pot) to the brood when frames removed |
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Brood |
Brood appears spotty |
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Cappings |
Sealed brood. The cappings become discoloured and convex
(sunk inwards). Some may be punctured. |
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Larvae appearance |
Dead larvae may be
sticky and ropey use a tooth
pick. Their colour is dull white,
becoming light brown to almost black. |
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Scales (larvae) |
Dead dried larvae
(called scales) are difficult to remove.
Fine threadlike tongue of dead
pupae maybe present. |
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Spotty
brood patter pepper pot: |
Black
shrunken caps and scales (dead larvae) |
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Scales visible in the cells |
Torn
cappings in a collapsing hive |
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Infectivity |
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The larvae are
infected within the 1st couple of days. The bacteria cannot
affect hatched larvae older than 3 days of age. The bacteria is
spread between colonies by robbing The bacteria gains
access to the larvae trough infected honey The bacteria produce
spores which are extremely resistant and can survive 40 years. (Note paeni next to in Greek) |
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Transmission |
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Through infected
honey. Spores are highly resistant and
can remain viable for over 70 years. |
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Post-mortem Lesions |
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Dead larvae after 16
days of age (worker) post-capping Larvae are not pure
white may range from translucent, tan to black. |
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Diagnosis |
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Culture of the
organism |
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Field diagnosis
using lateral flow devices looking for
antibodies in the bees |
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Rope test using a
match stick on the dead larvae shown left. Note this is not diagnostic as most brown decomposing
larvae may do this. |
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Treatment |
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Inform local authorities several countries will destroy the hive |
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Tetracycline, Tylosin or Sulphathiazole |
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Note residue issues with honey |
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Control |
Strict biosecurity do not shape equipment, Avoid second hand equipment |
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Burn equipment which has become infected |
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When applying antibiotic medications, mix the antibiotic with powdered sugar. Sprinkle the mixture on the edge of the brood-nest avoiding spilling directly into the brood. The house bees will consume the medication and feed it to the larvae. |
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Common differentials |
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European Foul Brood not larvae die before being capped. |
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Zoonosis |
None |
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