American Foulbrood (AFB)

American Foulbrood (AFB)#

1 . What is the causative agent?

Paenibacillus larvae (spore-forming bacterium)

2 . How does AFB spread?

Only spores can initiate infection

3 . How long do AFB spores last?

Indefinitely

4 . How are AFB spores spread?

By contact:

  • Drifting or robbing bees

  • Contaminated equipment

  • Hive tools and gloves

  • Honey and pollen

5 . LD₅₀ for AFB spores

10–35 spores kill 50% of larvae

6 . How do AFB spores kill larvae?

  • Larvae ingest spores

  • Bacteria penetrate gut wall

  • Enter hemolymph

  • Cause septicemia

7 . At what stage does AFB kill brood?

Prepupal or pupal stage, after capping.

8 . Where do infective spores persist?

In hard scales lying lengthwise on the bottom of brood cells

9 . How many spores can persist in one scale?

1–2 billion spores

10 . Appearance of larvae infected with AFB

Dull white → tan → brown

11 . What is the ropy test?

  • Insert toothpick into suspect cell.

  • Stir and slowly withdraw.

  • Ropy, stringy material indicates AFB.

12 . Signs of AFB when inspecting comb

  • Foul odor

  • Sunken cappings

  • Perforated cappings

  • Protruding pupal tongue

  • Dark, hard scales in cell bottoms If AFB is suspected, immediately contact your local bee inspector.

13 . Treatment for AFB

  • State-regulated response

  • May include:

    • Burning entire colony and equipment

    • Shake swarm into new equipment

    • Feeding and antibiotic treatment (e.g., Terramycin)

    • Infected equipment is destroyed

14 . Preventing AFB

  • Regular inspections

  • Purchase bees from reputable sources

  • Avoid used equipment unless properly sterilized

  • Scorch woodenware if contamination is suspected

  • Contact bee inspectors for testing